Organic Chemistry

Description

Efnisyfirlit

Front Matter
Preface
TO THE INSTRUCTOR
TO THE STUDENT
Acknowledgments
Author
1 Review of Atomic and Molecular Structure
1.1 INTRODUCTION
FIGURE 1.1 Conversion of ammonium isocyanate to urea. Note: I hope you are familiar with the use of a capital Greek delta, Δ, to indicate heat. New symbols and acronyms will be explained the first time they are used, but they are also collected together in Appendix A.
Quick Reminder on Analysis
PROBLEM 1.1
1.2 ATOMIC AND MOLECULAR STRUCTURE
1.2.1 ORBITALS OF THE HYDROGEN ATOM
FIGURE 1.2 1s orbital of the hydrogen atom.
FIGURE 1.3 Cutaway diagram of the hydrogen 2s orbital.
FIGURE 1.4 2p orbital.
FIGURE 1.5 The three 2p orbitals.
FIGURE 1.6 The 1s orbital.
FIGURE 1.7 Probability of electron position for the hydrogen 1s orbital.
FIGURE 1.8 Probability of the electron position for the hydrogen 2s orbital.
FIGURE 1.9 Probability for the electron position for the hydrogen 3s orbital.
FIGURE 1.10 Probability for the electron position for the hydrogen 4s orbital.
FIGURE 1.11 Probabilities for 1s, 2s, 3s, and 4s orbitals.
FIGURE 1.12 p Orbital.
FIGURE 1.13 Common representations of p orbitals.
1.2.2 MULTIELECTRON ATOMS
FIGURE 1.14 Set of five 3d orbitals, from left to right m = −2, −1, 0, 1, 2.
TABLE 1.1 Configurations of the Elements of the First Row of the Periodic Table
PROBLEM 1.2
PROBLEM 1.3
1.3 BONDING
FIGURE 1.15 Formation of a hydrogen molecule. (a) Hydrogen is orbitals combine to form the bond in H2. (b) Plot of energy against internuclear distance for the formation of the H2 molecule.
FIGURE 1.16 Bonding and antibonding orbitals of the hydrogen molecule.
FIGURE 1.17 Molecular orbitals of H2.
FIGURE 1.18 How can we form a C–H bond?
FIGURE 1.19 How can we form a C–C bond?
FIGURE 1.20 Formation of a π-bond.
FIGURE 1.21 Formation of π- and π*-orbitals from 2pz orbitals.
REVIEW PROBLEMS
2 Alkanes and Friends: Structure, Bonding, Properties, and Nomenclature
2.1 INTRODUCTION
2.2 HYBRIDIZATION IN METHANE, AMMONIA, AND WATER
FIGURE 2.1 sp3 orbitals.
FIGURE 2.2 sp3 hybridization and bonding in methane.
FIGURE 2.3 Paired and unpaired electrons in the sp3 orbitals of nitrogen in ammonia.
FIGURE 2.4 Paired and unpaired electrons in the sp3 orbitals of oxygen in water.
PROBLEM 2.1
2.3 DRAWING MOLECULES
Key Points from Sections 2.1 through 2.3
2.4 INTRODUCTION TO ALKANES
TABLE 2.1 Low-Molecular-Weight Alkanes
2.4.1 FORMAL NOMENCLATURE OF ALKANES
FIGURE 2.5 Organic chemists do have a sense of humor.
TABLE 2.2 Nomenclature of Alkanes
2.4.2 STRUCTURAL ISOMERS AND FORMAL NOMENCLATURE
TABLE 2.3 Nomenclature of Substituents
Digression: Nonpolar (Hydrophobic) Interactions
TABLE 2.4 Interionic and Intermolecular Forces
FIGURE 2.6 Instantaneous and induced dipoles attract.
FIGURE 2.7 Energy diagram for the approach of two argon atoms.
FIGURE 2.8 Elemental halogens.
TABLE 2.5 Melting and Boiling Points of Nonpolar Compounds
FIGURE 2.9 Dispersion forces depend on molecular shape.
2.4.3 HALOALKANES
Digression: Interactions of Polar Molecules
FIGURE 2.10 Attraction of permanent dipoles.
TABLE 2.6 Physical Properties of Fluorinated Methanes
PROBLEM 2.2
PROBLEM 2.3
2.4.4 CYCLOALKANES
PROBLEM 2.4
PROBLEM 2.5
Focus on Hydrocarbons as Fuels
TABLE 2.7 Fractions of Saturated Hydrocarbons
Key Points from Section 2.4
2.5 STABILITY, STRAIN, AND PROPERTIES OF ALKANES AND CYCLOALKANES
TABLE 2.8 Strain Energy in Cycloalkanes
TABLE 2.9 Heats of Combustion of Lower Alkanes
TABLE 2.10 Heats of Combustion of Cycloalkanes per Carbon Atom
TABLE 2.11 Physical Properties of Alkanes
Key Points from Section 2.5
REVIEW PROBLEMS
3 Alkenes, Alkynes, and Aromatic Compounds
3.1 ALKENES
3.1.1 BONDING IN ALKENES
FIGURE 3.1 Calculated sp2 orbitals.
FIGURE 3.2 Sigma bond framework of ethene, showing orbitals.
FIGURE 3.3 π- and π*-orbitals of ethene.
FIGURE 3.4 Bonding orbitals of ethene.
TABLE 3.1 Bond Strengths and Lengths in Hydrocarbons
TABLE 3.2 Hydrocarbon Formulae
PROBLEM 3.1
Focus on Ethene in Fruit Ripening
FIGURE 3.5 Biosynthesis of ethene by plants.
3.1.2 NOMENCLATURE OF ALKENES
FIGURE 3.6 Simple alkenes.
PROBLEM 3.2
PROBLEM 3.3
3.1.3 GEOMETRIC ISOMERISM IN ALKENES
PROBLEM 3.4
PROBLEM 3.5
3.1.4 STABILITY OF ALKENES AND THE EFFECT OF CONJUGATION
TABLE 3.3 Molar Heats of Combustion of Alkenes of Formula C4H8
FIGURE 3.7 Hydrogenation of 1-butene.
TABLE 3.4 Heats of Hydrogenation of Linear Butenes
FIGURE 3.8 Molecules containing conjugated multiple bonds.
FIGURE 3.9 Molecules containing non-conjugated, non-interacting, multiple bonds.
PROBLEM 3.6
FIGURE 3.10 Hydrogenation of 1,3- and 1,4-pentadiene.
FIGURE 3.11 Energetics of pentadiene hydrogenation.
FIGURE 3.12 Simplified picture of the molecular orbitals of butadiene.
PROBLEM 3.7
Focus on Naturally Occurring Polyenes
Key Points from Section 3.1
3.2 AROMATIC HYDROCARBONS
FIGURE 3.13 Loschmidt structures of aromatic compounds, 1861.
3.2.1 BONDING IN AROMATIC COMPOUNDS
FIGURE 3.14 Image of a single suspended sheet of graphene taken with TEAM 0.5, showing individual carbon atoms (yellow) on the honeycomb lattice.
FIGURE 3.15 Hydrogenation of cyclohexene and benzene.
FIGURE 3.16 Energy diagram for benzene and cyclohexene hydrogenation.
FIGURE 3.17 Energy diagram of the molecular orbitals of benzene.
FIGURE 3.18 Lowest-energy π-molecular orbital of benzene (oblique view).
FIGURE 3.19 Lowest-energy π-molecular orbital of benzene (top down view).
FIGURE 3.20 Bonding molecular orbitals of benzene with one node.
FIGURE 3.21 Molecular orbitals of benzene containing two nodes.
FIGURE 3.22 Molecular orbital of benzene containing three nodes.
FIGURE 3.23 Molecular orbitals of cyclobutadiene.
FIGURE 3.24 Energies of the molecular orbitals in the cyclopentadienyl system.
PROBLEM 3.8
3.2.2 NOMENCLATURE OF BENZENE DERIVATIVES
FIGURE 3.25 Some common names of monosubstituted benzene derivatives.
FIGURE 3.26 Nitration of toluene.
PROBLEM 3.9
PROBLEM 3.10
3.3 ALKYNES: HYDROCARBONS CONTAINING TRIPLE BONDS
FIGURE 3.27 sp hybrid orbitals.
FIGURE 3.28 Bonding in ethyne.
FIGURE 3.29 The lower alkynes.
PROBLEM 3.11
PROBLEM 3.12
Key Points from Sections 3.2 and 3.3
3.4 RESONANCE
FIGURE 3.30 Resonance forms of benzene.
Key Points: A Series of Simple Rules Will Help You to Write Resonance Forms
FIGURE 3.31 Connecting resonance forms using curly arrows.
PROBLEM 3.13
FIGURE 3.32 Molecular orbitals of the allyl anion.
FIGURE 3.33 Molecular orbitals of the allyl cation.
FIGURE 3.34 Calculated molecular orbitals of the allyl system.
FIGURE 3.35 Resonance forms of the stable cyclopentadienyl anion.
FIGURE 3.36 Resonance forms of the unstable cyclopentadienyl cation.
REVIEW PROBLEMS
4 Heteroatom-Containing Functional Groups
4.1 Compounds Containing sp3 Nitrogen Atoms
Quick Digression on Dipole Moments and Hydrogen Bonds
FIGURE 4.1 Dipole moments of dichloroethenes.
TABLE 4.1 Boiling Points of Elemental Hydrides
FIGURE 4.2 Protonation of ammonia and amines.
Focus on Amines: From Stinks to Stimulants
FIGURE 4.3 Some naturally occurring polyamines.
FIGURE 4.4 Medicinal and psychoactive amines.
4.2 Molecules Containing sp2 Nitrogen Atoms
FIGURE 4.5 Classes of compounds containing sp2 nitrogen atoms.
4.3 MOLECULES WITH sp-HYBRIDIZED NITROGEN
FIGURE 4.6 Bonding in MeCN. While both lobes of p orbitals are shown, only the major lobe of sp3, sp2, or sp orbitals is shown.
TABLE 4.2 Melting and Boiling Points of Nitriles and Alkynes
PROBLEM 4.1
PROBLEM 4.2
PROBLEM 4.3
PROBLEM 4.4
Key Points from Sections 4.1 through 4.3
4.4 Compounds Containing sp3 Oxygen
4.4.1 ALCOHOLS
TABLE 4.3 Properties of Some Common Alcohols
Focus on Proof Spirit and Moonshine
4.4.2 ETHERS
Digression: More about Hydrogen Bonds
FIGURE 4.7 Transfer of a proton between water molecules.
FIGURE 4.8 Molecules with intramolecular hydrogen bonds.
PROBLEM 4.5
PROBLEM 4.6
PROBLEM 4.7
4.4.3 CROWN ETHERS, IONOPHORES, AND THE SOLVATION OF METAL IONS
FIGURE 4.9 Solvation of sodium chloride in water.
FIGURE 4.10 Molecules that can act as multidentate ligands.
Focus on Tetrodotoxin
PROBLEM 4.8
Key Points from Section 4.4
4.5 Compounds Containing sp2 Oxygen
4.5.1 ALDEHYDES
PROBLEM 4.9
4.5.2 KETONES
PROBLEM 4.10
4.5.3 CARBOXYLIC ACIDS
PROBLEM 4.11
4.5.4 CARBOXYLATE ESTERS
FIGURE 4.11 Formation of an ester.
PROBLEM 4.12
4.5.5 AMIDES
4.5.6 ACYL HALIDES AND ANHYDRIDES
PROBLEM 4.13
PROBLEM 4.14
PROBLEM 4.15
Key Points from Section 4.5
TABLE 4.4 Summary and Priorities in Nomenclature
4.6 PRIORITIES IN NOMENCLATURE
4.7 STRUCTURE AND BONDING IN SOME HIGHLY REACTIVE SPECIES
FIGURE 4.12 Homolytic cleavage of a carbon–carbon bond.
FIGURE 4.13 Heterolytic cleavage of a carbon–carbon bond.
4.7.1 CARBOCATIONS
FIGURE 4.14 Relative stability of simple carbocations.
FIGURE 4.15 Formation of carbocations from alcohols.
FIGURE 4.16 Production of relatively stable carbocations from alcohols.
PROBLEM 4.16
Focus on Some Very Stable Cations
TABLE 4.5 pKR+ Values for Carbocations
FIGURE 4.17 Stabilities of simple carbanions.
4.7.2 CARBANIONS
PROBLEM 4.17
4.7.3 CARBON-CENTERED RADICALS
Key Points from Section 4.7
4.8 MORE RESONANCE
FIGURE 4.18 Addition of cyanide to 4.83.
FIGURE 4.19 Key points from Section 4.8—motifs for resonance.
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
5 Purification and Identification of Organic Compounds 1
5.1 INTRODUCTION
5.2 PURIFICATION OF ORGANIC COMPOUNDS
5.2.1 CRYSTALLIZATION
FIGURE 5.1 Hot gravity filtration.
FIGURE 5.2 Collection of crystals on a glass frit.
5.2.2 DISTILLATION AND SUBLIMATION
FIGURE 5.3 Simple distillation.
FIGURE 5.4 Fractional distillation of liquids.
FIGURE 5.5 Simple sublimation apparatus.
PROBLEM 5.1
Key Points from Sections 5.1, 5.2.1, and 5.2.2
5.2.3 CHROMATOGRAPHY
TABLE 5.1 Common Types of Chromatography
FIGURE 5.6 TLC—at the start of the experiment.
FIGURE 5.7 TLC—after 5–10 min.
FIGURE 5.8 Visualization of spots on a TLC plate using UV light.
FIGURE 5.9 Visualization of TLC plate using iodine.
FIGURE 5.10 Column chromatography setup.
FIGURE 5.11 Column chromatography in progress.
FIGURE 5.12 Pressure driven flash chromatography.
FIGURE 5.13 HPLC separation of opiates. (1) Normorphine, (2) morphine, (3) norcodeine, (4) naloxone, (5) codeine, (6) hydrocodeine, (7) 6-monoacetylmorphine, (8) ethylmorphine, (9) acetyldihydrocodeine, (10) thebacone, (11) acetylcodeine, (12) heroin, (13) internal standard, (14) papaverine, (15) dextromethorphan, (16) noscapine, (17) buprenorphine, (18) normethadone, and (19) methadone.
FIGURE 5.14 Schematic of a gas chromatograph.
PROBLEM 5.2
Key Points from Section 5.2.3
5.3 MASS SPECTROMETRY
FIGURE 5.15 Schematic of a mass spectrometer.
FIGURE 5.16 Mass spectrum of methane.
FIGURE 5.17 Mass spectrum of bromoethane.
FIGURE 5.18 Mass spectrum of 2-chloropropane.
FIGURE 5.19 Mass spectrum of chlorobenzene.
FIGURE 5.20 Mass spectrum of aniline.
TABLE 5.2 Mass Spectrometric Fragmentations
FIGURE 5.21 Mass spectrum of 3,3-dimethylhexane.
FIGURE 5.22 Mass spectrum of n-octane.
FIGURE 5.23 Fragmentation of 3,3-dimethylhexane.
FIGURE 5.24 Stabilization of carbocations by lone pair donation.
FIGURE 5.25 Mass spectrum of 2-methyl-2-butanol.
FIGURE 5.26 Fragmentation of 2-methyl-2-butanol.
FIGURE 5.27 Mass spectrum of 3-heptanone.
FIGURE 5.28 Fragmentation of 3-heptanone.
PROBLEM 5.3
PROBLEM 5.4
Focus on Stable Isotope Mass Spectrometry
FIGURE 5.29 Schematic of an isotope ratio mass spectrometer.
FIGURE 5.30 Deuterium isotope distribution in annual precipitation.
Key Points from Section 5.3
5.4 UV/VISIBLE SPECTROSCOPY
FIGURE 5.31 The electromagnetic spectrum.
FIGURE 5.32 Transitions in UV spectroscopy.
TABLE 5.3 π to π* Transitions in Conjugated Polyenes
FIGURE 5.33 UV spectra of the polyenes CH3(CHCH)nCH3 for n = 3, 4, and 5.
FIGURE 5.34 UV spectrum of benzene in heptane solvent.
FIGURE 5.35 UV/Visible spectrum of β-carotene.
PROBLEM 5.5
PROBLEM 5.6
Focus: What Does Visible Really Mean?
FIGURE 5.36 Frequency response of the three types of cones in the human eye.
FIGURE 5.37 Absorbances of visual pigments of birds.
Key Points from Section 5.4
5.5 INFRARED SPECTROSCOPY
5.5.1 INTRODUCTION AND THEORY
FIGURE 5.38 Sodium chloride plates and holder.
FIGURE 5.39 Hydraulic press to make KBr discs.
FIGURE 5.40 Vibrational modes of CO2.
FIGURE 5.41 Vibrational modes of a CH2 group.
FIGURE 5.42 Characteristic frequencies in the IR spectrum.
TABLE 5.4 Some IR Stretching Frequencies
FIGURE 5.43 IR spectrum of chloroform, CHCl3.
FIGURE 5.44 IR spectrum of deuterochloroform CDCl3.
5.5.2 REGIONS OF THE INFRARED SPECTRUM
FIGURE 5.45 IR spectrum of propanenitrile.
FIGURE 5.46 IR spectrum of benzene.
TABLE 5.5 Carbonyl Stretching Frequencies
FIGURE 5.47 Resonance forms of carbonyl compounds and α,β-unsaturated carbonyl compounds.
FIGURE 5.48 IR spectrum of neat propanol.
FIGURE 5.49 IR spectrum of solution of 1-propanol in tetrachloromethane.
TABLE 5.6 C–H Absorption in the IR Spectrum
FIGURE 5.50 IR spectrum of octane.
FIGURE 5.51 IR spectrum of 2-methylheptane.
FIGURE 5.52 IR spectrum of 1-octene.
FIGURE 5.53 IR spectrum of 1-octyne.
FIGURE 5.54 IR spectrum of propylbenzene.
FIGURE 5.55 IR spectrum of cyclopentanol.
FIGURE 5.56 IR spectrum of propylamine, CH3CH2CH2NH2.
FIGURE 5.57 IR spectrum of dipropylamine.
FIGURE 5.58 IR spectrum of 2-butanone.
FIGURE 5.59 IR spectrum of butanal.
FIGURE 5.60 IR spectrum of propanoic anhydride.
FIGURE 5.61 IR spectrum of propanoic acid.
FIGURE 5.62 IR spectrum of ethyl propanoate.
FIGURE 5.63 IR spectrum of octanamide.
Focus on Molecules in the Cosmos
FIGURE 5.64 PAHs detected in cosmic dust.
FIGURE 5.65 IR spectrum of light toward protostar W33A.
PROBLEM 5.7
Key Points from Section 5.5
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
6 Identification of Organic Compounds 2: Nuclear Magnetic Resonance Spectroscopy
6.1 INTRODUCTION
TABLE 6.1 Nuclear Spins of Some Common Nuclei
FIGURE 6.1 Spin states in NMR spectroscopy.
FIGURE 6.2 Splitting of nuclear spin energy levels in a magnetic field.
6.2 CHEMICAL SHIFTS
FIGURE 6.3 The δ-scale for proton NMR spectra.
FIGURE 6.4 The δ-scale for 13C NMR spectra.
PROBLEM 6.1
FIGURE 6.5 Shielding of an isolated nucleus by the movement of the surrounding electron cloud.
FIGURE 6.6 Typical free induction decay.
FIGURE 6.7 1H NMR spectrum of dimethoxymethane. The lower axis is the chemical shift scale in terms of δ (ppm) and the upper scale gives it in frequency units. TMS has been added to the sample and the signal is seen at δ 0.
FIGURE 6.8 1H NMR spectrum of dimethoxymethane with integration. The integration is the blue superimposed curve for each signal. The vertical height of the integral tells us how many protons of each type there are. Only a ratio can be obtained this way.
TABLE 6.2 Typical Chemical Shifts of Protons Attached to sp3 Carbon Atoms
TABLE 6.3 Chemical Shifts of Residual Protons in Common Deuterated Solvents
FIGURE 6.9 Ring currents in alkynes and aromatic compounds.
PROBLEM 6.2
Key Points from Sections 6.1 and 6.2
6.3 SPIN–SPIN COUPLING
6.3.1 SIMPLE ALIPHATIC SYSTEMS
FIGURE 6.10 Proton NMR spectrum of 1,1,2-tribromo-3,3-dimethylbutane.
FIGURE 6.11 Proton NMR spectrum of 1,1,2-trichloroethane.
FIGURE 6.12 Expansion of the proton NMR spectrum of 1,1,2-trichloroethane.
FIGURE 6.13 Schematic of spin states in an A2B system.
FIGURE 6.14 Proton NMR spectrum of 1,1-dichloroethane.
FIGURE 6.15 Schematic of spin states in an A3B system.
FIGURE 6.16 Quartet in an NMR spectrum from coupling to three equivalent protons.
FIGURE 6.17 Pascal’s triangle.
FIGURE 6.18 Proton NMR spectrum of bromoethane.
FIGURE 6.19 Proton NMR spectrum of 1,3-dichloropropane.
FIGURE 6.20 Proton NMR spectrum of 2-bromopropane.
Key Points from Section 6.3.1
PROBLEM 6.3
6.3.2 Spin–Spin Coupling Involving Protons Attached to sp2 Carbon Atoms
FIGURE 6.21 Sections of the proton NMR spectrum of E and Z-3-chloropropenoic acid.
FIGURE 6.22 Proton NMR spectrum of 4-bromonitrobenzene.
FIGURE 6.23 Proton NMR spectrum of E-2-butenoic acid with expansions. Note that the OH peak is at approx. δ 12 and not shown here.
FIGURE 6.24 Proton NMR spectrum of salicylic acid.
TABLE 6.4 Proton–Proton Spin–Spin Coupling Constants
Focus: Tips on Analysis of the Splitting Patterns for Benzene Rings
FIGURE 6.25 Splitting patterns in the proton NMR spectra of polysubstituted aromatic compounds.
FIGURE 6.26 Proton NMR spectrum of ortho-bromonitrobenzene.
FIGURE 6.27 Proton NMR spectrum of meta-bromonitrobenzene. Note that Hb and Hd show meta-couplings both to each other and to Ha.
FIGURE 6.28 Proton NMR spectrum of para-bromonitrobenzene.
PROBLEM 6.4
FIGURE 6.29 Splitting of Hb in 6.10.
FIGURE 6.30 Splitting of Ha in 6.10.
FIGURE 6.31 Splitting of Hc in 6.10.
FIGURE 6.32 Proton NMR spectrum of vinyl 2,2-dimethylpropanoate.
FIGURE 6.33 Schematic splitting diagram for the vinyl protons of vinyl 2,2-dimethylpropanoate.
PROBLEM 6.5
6.3.3 SPIN–SPIN DECOUPLING
FIGURE 6.34 Decoupling of a simple two-proton system.
FIGURE 6.35 Proton NMR spectrum of 1-nitropropane.
FIGURE 6.36 Proton NMR spectrum of 1-nitropropane with the methyl group irradiated.
FIGURE 6.37 Proton NMR spectrum of 1-nitropropane with the C-2H2 group irradiated.
FIGURE 6.38 Proton NMR spectrum of 1-nitropropane with the C-1H2 group irradiated.
6.4 PROTONS ATTACHED TO OXYGEN AND NITROGEN
FIGURE 6.39 Proton NMR spectrum of 4-methylbenzoic acid.
FIGURE 6.40 Proton NMR spectra of (a) dry and (b) “wet” ethanol.
FIGURE 6.41 Proton NMR spectrum of 2-methyl-2-butyn-2-ol.
FIGURE 6.42 Proton NMR spectrum of 2-methyl-2-butyn-2-ol after D2O shake.
FIGURE 6.43 Proton NMR spectrum of 4-hydroxy-4-methyl-2-pentanone.
FIGURE 6.44 Proton NMR spectrum of 4-hydroxy-4-methyl-2-pentanone after a D2O shake.
Focus on OH Chemical Shifts: pKa, H-Bonding, and Temperature
TABLE 6.5 Proton NMR Spectrum of Methanol in Other Solvents
TABLE 6.6 Proton Chemical Shift of the OH Proton in Phenol
PROBLEM 6.6
Focus on Magnetic Resonance Imaging
FIGURE 6.45 MRI scan of a human knee.
Key Points from Sections 6.3.2, 6.3.3, and 6.4
6.5 13C NMR SPECTROSCOPY
FIGURE 6.46 13C chemical shift ranges.
FIGURE 6.47 13C NMR spectrum of 4-amino-3-methylbenzoic acid, 6.17.
FIGURE 6.48 Proton NMR spectrum of 1-bromohexane (500 MHz).
FIGURE 6.49 Carbon NMR spectrum of 1-bromohexane (125 MHz).
PROBLEM 6.7
Focus on Phosphorus and Fluorine NMR Spectroscopy
TABLE 6.7 Fluorine–Fluorine Coupling Constants in NMR Spectroscopy
FIGURE 6.50 31P NMR spectrum of Wilkinson’s complex.
Key Points from Section 6.5
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
7 Stereochemistry
7.1 INTRODUCTION
FIGURE 7.1 Ball and stick model of proline.
FIGURE 7.2 Skeletal model of tryptophan.
FIGURE 7.3 Computer-generated space-filling model of caffeine.
PROBLEM 7.1
PROBLEM 7.2
7.2 CONFORMATIONS OF ALKANES
PROBLEM 7.3
FIGURE 7.4 Changes in energy on rotation about the single bond of ethane.
FIGURE 7.5 Conformations of butane.
FIGURE 7.6 Energy changes induced by the rotation about the C2–C3 bond of butane.
Key Points from Sections 7.1 and 7.2
7.3 CYCLOALKANES
7.3.1 CYCLOPROPANE
FIGURE 7.7 Bonding in cyclopropane.
7.3.2 CYCLOBUTANE
7.3.3 CYCLOPENTANE
7.3.4 SIX-MEMBERED RINGS
FIGURE 7.8 Ball and stick model of the chair form of cyclohexane.
FIGURE 7.9 Energy profile for the interconversion of various conformations of cyclohexane.
FIGURE 7.10 Inversion of a cyclohexane ring.
FIGURE 7.11 Gauche interactions in a substituted cyclohexane.
TABLE 7.1 Proportions of Axial Isomers in Monosubstituted Cyclohexanes
FIGURE 7.12 Equilibrium between conformers of monosubstituted cyclohexanes.
FIGURE 7.13 Conformational equilibria in 1,2-disubstituted cyclohexanes.
PROBLEM 7.4
7.3.5 MEDIUM AND LARGE RINGS
PROBLEM 7.5
7.3.6 RING SYNTHESIS
Key Points from Section 7.3
7.4 CHIRALITY
Short Digression on Symmetry
FIGURE 7.14 Schematic of a polarimeter.
PROBLEM 7.6
Focus on the Origins of Natural Chirality and Asymmetry*
7.4.1 ABSOLUTE CONFIGURATION
PROBLEM 7.7
PROBLEM 7.8
7.4.2 MOLECULES WITH MORE THAN ONE CHIRAL CENTER
Focus on Enantiomers with Different Biological Roles and Effects
PROBLEM 7.9
7.4.3 CHIRAL MOLECULES WITH NONCARBON CHIRAL CENTERS
FIGURE 7.15 Chiral centers at atoms other than carbon.
Focus: More on Chirality at Nitrogen
7.4.4 OTHER CHIRAL COMPOUNDS
PROBLEM 7.10
7.5 FISCHER PROJECTIONS
FIGURE 7.16 Manipulation of Fischer projections.
PROBLEM 7.11
Key Points from Sections 7.4 and 7.5
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
8 Introduction to Mechanism
8.1 INTRODUCTION
8.2 STUDYING ORGANIC REACTION MECHANISMS
8.2.1 THERMODYNAMICS
FIGURE 8.1 Energetics of an exothermic one-step process.
FIGURE 8.2 Homolytic and heterolytic cleavage of bonds.
Quick Review of Arrow Types Used in Organic Chemistry
FIGURE 8.3 Processes with positive or negative entropic terms. (a) Two molecules react to give three molecules—entropy increases. (b) Two molecules combine to give one—entropy decreases in the Diels–Alder reaction.
FIGURE 8.4 Intramolecular processes may be favored because they have low entropy of activation.
FIGURE 8.5 Energetics of a two-step process where the first step is rate controlling.
FIGURE 8.6 Energetics of a two-step process where the second step is rate controlling.
FIGURE 8.7 Some reactions of 2-methyl-2-chloropropane (tert-BuCl).
PROBLEM 8.1
8.2.2 KINETICS
FIGURE 8.8 Unimolecular and bimolecular RDSs.
FIGURE 8.9 Kinetics of substitution of alkyl halides.
8.2.3 STUDY OF PRODUCTS
FIGURE 8.10 Proposed mechanism for hydrolysis of tert-butyl bromide.
FIGURE 8.11 Hydrolysis and elimination reactions of tert-butyl chloride.
FIGURE 8.12 Product analysis shows what a mechanism can’t be.
FIGURE 8.13 Bromination of a chiral ketone.
FIGURE 8.14 Reactions capable of giving kinetic or thermodynamic products. In practice, both isomers may be isolated from this reaction, depending on the temperature and duration of the reaction.
FIGURE 8.15 Energetics of the formation of kinetic and thermodynamic products.
8.2.4 ISOTOPIC LABELING AND KINETIC ISOTOPE EFFECTS
FIGURE 8.16 Labeling techniques in mechanistic studies.
FIGURE 8.17 The NIH shift in the hydroxylation of phenylalanine.
FIGURE 8.18 KIEs indicate whether a C–H bond is broken in the RDS.
8.2.5 STUDY OF INTERMEDIATES
FIGURE 8.19 Observation of an unstable intermediate.
FIGURE 8.20 Sometimes intermediates can be isolated.
Review of Reactive Intermediates and a Little More
FIGURE 8.21 Formation of radical anions. In this example, the two resonance forms contribute equally.
FIGURE 8.22 Singlet and triplet methylene.
Key Points from Section 8.2
8.3 CLASSIFICATION OF REACTIONS
FIGURE 8.23 Addition reactions.
FIGURE 8.24 Elimination reactions.
FIGURE 8.25 Substitution reaction.
FIGURE 8.26 Condensation reaction.
FIGURE 8.27 Rearrangement reactions.
FIGURE 8.28 Isomerization reaction.
PROBLEM 8.2
8.4 ACIDS AND BASES
8.4.1 ORBITAL EFFECTS
TABLE 8.1 pKa Values (in Water) for Compounds Important in Organic Chemistry Where the Proton Is Attached to a Heteroatom
TABLE 8.2 pKa Values for Carbon Acids
PROBLEM 8.3
8.4.2 ELECTRONEGATIVITY
PROBLEM 8.4
8.4.3 INDUCTIVE EFFECTS
PROBLEM 8.5
8.4.4 DELOCALIZATION
FIGURE 8.29 Delocalization of charge stabilizes conjugate bases.
FIGURE 8.30 More delocalization of charge to stabilize conjugate bases.
FIGURE 8.31 Anions of carbonyl compounds.
PROBLEM 8.6
8.4.5 SOLVATION
8.4.6 HYDROGEN BONDING
FIGURE 8.32 pKa values of 2- and 4-hydroxybenzoic acid.
PROBLEM 8.7
8.4.7 STERIC EFFECTS
8.4.8 AROMATICITY
PROBLEM 8.8
Key Points from Sections 8.3 and 8.4
8.5 TAUTOMERS: A SLIGHT DIGRESSION
FIGURE 8.33 Tautomerization of acetone.
PROBLEM 8.9
8.6 WRITING MECHANISMS USING CURLY ARROWS
FIGURE 8.34 Protonation of nucleophiles.
FIGURE 8.35 Drawing the protonation of amines.
PROBLEM 8.10
FIGURE 8.36 Protonation of anions.
FIGURE 8.37 Using the π-electrons of an alkene as a nucleophile.
PROBLEM 8.11
FIGURE 8.38 Reactions of nucleophiles with various cations.
FIGURE 8.39 Reactions of Lewis acids with nucleophiles.
FIGURE 8.40 Heterolytic fission.
FIGURE 8.41 H–Br as an electrophile.
FIGURE 8.42 Molecules with polar σ-bonds as electrophiles.
FIGURE 8.43 Electrophiles with weak σ-bonds.
FIGURE 8.44 Reaction of nucleophiles with carbonyl compounds.
Key Points from Section 8.6
PROBLEM 8.12
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
9 Nucleophilic Substitution at Saturated Carbon
9.1 INTRODUCTION
9.2 MECHANISTIC TYPES
FIGURE 9.1 Prototype substitution reaction at sp3 carbon atom. R1, R2, R3 may be hydrogen, alkyl or aryl; no particular stereochemical outcome should be inferred at this point.
FIGURE 9.2 Mechanism of SN1 substitution.
FIGURE 9.3 Energy profile of a typical SN1 reaction.
FIGURE 9.4 Mechanism of the SN2 reaction.
PROBLEM 9.1
9.3 STEREOCHEMICAL IMPLICATIONS
FIGURE 9.5 Stereochemical outcome of an SN1 reaction.
FIGURE 9.6 SN1 reactions may produce diastereoisomers in unequal amounts.
FIGURE 9.7 Typical SN1 reactions.
TABLE 9.1 Outcomes of Various Possible Stereochemistries for SN2 Reactions
FIGURE 9.8 SN2 substitution goes with inversion of stereochemistry.
FIGURE 9.9 Typical SN2 reactions.
PROBLEM 9.2
PROBLEM 9.3
Key Points from Sections 9.1 through 9.3
9.4 EFFECT OF NUCLEOPHILE
TABLE 9.2 Relative Reactivity of Nucleophiles with Iodomethane
TABLE 9.3 Hard and Soft Acids and Bases
PROBLEM 9.4
9.5 EFFECT OF THE LEAVING GROUP
FIGURE 9.10 Selectivity in an SN2 reaction.
PROBLEM 9.5
Key Points from Sections 9.4 and 9.5
9.6 EFFECT OF SUBSTRATE STRUCTURE
9.6.1 SN1 REACTIONS
FIGURE 9.11 SN1 substitution at a secondary benzylic center.
PROBLEM 9.6
Focus on Carbocations
FIGURE 9.12 Relative rates of cation formation.
TABLE 9.4 Relative Rates of Solvolysis of Benzylic Halides
FIGURE 9.13 X-ray crystal structure of the trityl cation.
FIGURE 9.14 X-ray structure of the cationic portion of [Me3C+][Sb2F11].
TABLE 9.5 Energy Required for Heterolytic Dissociation of Gas Phase Hydrocarbons
FIGURE 9.15 Relative rates of solvolysis of bicyclic halides.
FIGURE 9.16 X-ray crystal structure of 3,5,7-trimethyl adamantyl cation, showing flattening at C-1.
9.6.2 SN 2 REACTIONS
A Quick Aside on Relative and Absolute Stereochemistry
FIGURE 9.17 Steric hindrance inhibits SN2 reactions.
FIGURE 9.18 SN2 opening of epoxides.
FIGURE 9.19 SN2 opening of epoxides occurs selectively at the less hindered center.
PROBLEM 9.7
9.7 EFFECT OF SOLVENTS
TABLE 9.6 Relative Rate of Reaction of tert-Butyl Chloride in Various Solvents
FIGURE 9.20 Solvation of cations and anions by water.
FIGURE 9.21 Mechanism of substitution may depend on the solvent used.
9.8 COMPETING REACTIONS
FIGURE 9.22 Elimination may compete with both SN1 and SN2 reactions.
FIGURE 9.23 Rearrangement during SN1 solvolysis of a secondary halide.
PROBLEM 9.8
FIGURE 9.24 SN2 and SN2′ processes in allylic substitution.
FIGURE 9.25 Deuterium labeling is used to study allylic substitution.
FIGURE 9.26 SN1 substitution of an allylic system.
FIGURE 9.27 SN1 substitution of a nonsymmetrical allylic system.
PROBLEM 9.9
9.9 COMPETITION BETWEEN SN1 AND SN2 PROCESSES
PROBLEM 9.10
TABLE 9.7 Factors Favoring SN1 and SN2 Substitution
FIGURE 9.28 Competition between SN1 and SN2 processes.
Key Points from Sections 9.6 through 9.9
9.10 APPLICATIONS AND SCOPE OF THE REACTION
9.10.1 HALIDE IONS AS NUCLEOPHILES
FIGURE 9.29 Neither SN1 nor SN2 substitution occurs at sp2 or sp centers.
FIGURE 9.30 OH can be converted into a good leaving group by protonation.
FIGURE 9.31 Conversion of alcohols to bromides with HBr.
FIGURE 9.32 Conversion of alcohols to chlorides.
FIGURE 9.33 Mechanism of halogenation of alcohols with PX3.
FIGURE 9.34 Halogenation of alcohols using PX3.
FIGURE 9.35 Mechanism of chlorination of alcohols by PCl5.
FIGURE 9.36 Conversion of an alcohol to a chlorosulfite ester.
FIGURE 9.37 The SNi mechanism for chlorination of alcohols.
FIGURE 9.38 Formation of pyridine hydrochloride.
FIGURE 9.39 SN2 chlorination of alcohols using thionyl chloride in pyridine.
FIGURE 9.40 Formation of mesylates and tosylates.
FIGURE 9.41 Displacement of tosylates and mesylates by halide anions. Boc is a protecting group for amino groups—we’ll learn about this in Section 22.4.2.
FIGURE 9.42 Formation of iodides by displacement of other halides.
PROBLEM 9.11
PROBLEM 9.12
9.10.2 OXYGEN AND SULFUR AS NUCLEOPHILES
FIGURE 9.43 Williamson syntheses of ethers and thioethers.
FIGURE 9.44 Intramolecular reactions for ether synthesis.
FIGURE 9.45 Substitution of allylic halides by oxygen nucleophiles.
FIGURE 9.46 Displacement of halides by carboxylate anions.
PROBLEM 9.13
Key Points from Sections 9.10.1 and 9.10.2
9.10.3 NITROGEN NUCLEOPHILES
FIGURE 9.47 Reaction of methylamine with iodomethane.
FIGURE 9.48 Overreaction can be prevented by steric hindrance.
FIGURE 9.49 Clean monosubstitution of α-halocarboxylic acids by ammonia.
FIGURE 9.50 Gabriel phthalimide synthesis.
FIGURE 9.51 Substitution using hexamethylene tetramine as a proxy for ammonia—the Délepine reaction.
FIGURE 9.52 Azide is an excellent nucleophile.
FIGURE 9.53 Azide may also be used as a nucleophile in SN1 reactions.
FIGURE 9.54 Phosphines are excellent nucleophiles.
PROBLEM 9.14
Focus on Biological Substitution Reactions
FIGURE 9.55 Methylation using SAM.
FIGURE 9.56 Biological methylations using SAM.
FIGURE 9.57 Biosynthesis of mescaline from dopamine.
9.10.4 CARBON NUCLEOPHILES
FIGURE 9.58 SN2 reactions of cyanide ion.
FIGURE 9.59 Transformations of cyanide groups.
PROBLEM 9.15
FIGURE 9.60 Deprotonation of ethyne.
FIGURE 9.61 Alkylation of alkynes and subsequent transformations.
FIGURE 9.62 Preparation of Grignard reagents.
FIGURE 9.63 Synthesis of hydrocarbons by coupling of Grignard reagents with very reactive alkyl halides.
FIGURE 9.64 Reaction of Grignard reagents with epoxides.
FIGURE 9.65 Preparation of organolithium reagents.
FIGURE 9.66 Reaction of organolithium compounds with epoxides.
Focus on the Structures of Grignard Reagents and Organolithium Compounds
FIGURE 9.67 Mechanism of formation of Grignard reagents.
FIGURE 9.68 Structure of Ph3CMgBr(Et2O)2.
FIGURE 9.69 Structure of the THF solvate of methylmagnesium bromide.
FIGURE 9.70 Structure of diisopropyl ether solvate of ethylmagnesium bromide.
FIGURE 9.71 Structure of di-tert-butylmagnesium.
FIGURE 9.72 Solid-state structure of methyllithium.
FIGURE 9.73 Anions of β-dicarbonyl compounds as nucleophiles.
Focus on Epoxide Opening Reactions
FIGURE 9.74 Reactions of cyclohexene oxide with nucleophiles.
FIGURE 9.75 Ring opening of a nonsymmetrical epoxide in an SN2 process.
FIGURE 9.76 Ring opening of epoxides in synthesis.
FIGURE 9.77 Effect of pH on regiochemistry of epoxide ring opening.
PROBLEM 9.16
Key Points from Sections 9.10.3 and 9.10.4
9.11 NEIGHBORING GROUP PARTICIPATION AND INTRAMOLECULAR REACTIONS
FIGURE 9.78 Intramolecular SN2 reaction.
FIGURE 9.79 Intramolecular substitution reactions.
FIGURE 9.80 Retention of configuration involving neighboring group participation.
FIGURE 9.81 Neighboring group participation involving sulfur.
FIGURE 9.82 Mechanism of neighboring group participation by sulfur.
FIGURE 9.83 Neighboring group participation of a π-bond.
PROBLEM 9.17
Key Points from Section 9.11
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
10 Elimination Reactions
10.1 INTRODUCTION
10.2 MECHANISMS
10.2.1 E1 ELIMINATION, UNIMOLECULAR
10.2.2 E2 ELIMINATION, BIMOLECULAR
FIGURE 10.1 Mechanism of the E1 elimination process.
FIGURE 10.2 Mechanism of the E2 elimination process.
10.2.3 E1CB Elimination, Unimolecular, Conjugate Base
FIGURE 10.3 Mechanism of the E1cB elimination process.
Focus on Kinetics
FIGURE 10.4 E1cB reaction showing first-order kinetics.
FIGURE 10.5 E1cB reaction showing second-order kinetics.
10.3 STEREOCHEMISTRY
10.3.1 E1 ELIMINATIONS
10.3.2 E2 ELIMINATIONS
FIGURE 10.6 Stereochemical requirements of the E1 elimination process.
FIGURE 10.7 Trans-antiperiplanar elimination of HBr.
PROBLEM 10.1
FIGURE 10.8 E2 elimination is slowed by inaccessibility of the required conformation.
FIGURE 10.9 E2 elimination from a favorable conformation.
FIGURE 10.10 Thermal elimination of an amine oxide.
FIGURE 10.11 Pyrolytic elimination of a carboxylic acid from an ester.
10.3.3 E1CB Eliminations
FIGURE 10.12 Stereochemistry of E1cB elimination.
PROBLEM 10.2
Key Points from Sections 10.1 through 10.3
10.4 REGIOCHEMISTRY
FIGURE 10.13 Iodide ion dehalogenation of a vicinal dibromide.
FIGURE 10.14 Dehydrobromination of 2-bromobutane.
FIGURE 10.15 Regiochemistry of E1 elimination.
FIGURE 10.16 Steric effects on the regiochemistry of E1 eliminations.
PROBLEM 10.3
FIGURE 10.17 Stabilization of anions by resonance.
FIGURE 10.18 Transition states for elimination reactions.
FIGURE 10.19 Regiochemistry of E2 elimination reactions.
FIGURE 10.20 Steric effects on the regiochemistry of E2 elimination.
FIGURE 10.21 Regiochemistry of E2 elimination from 2-substituted pentanes.
TABLE 10.1 Features of Zaitsev and Hofmann Elimination in E2 Reactions
PROBLEM 10.4
Focus on Kinetic Isotope Effects (See Section 8.2.4)
FIGURE 10.22 Minimal kinetic isotope effects in E1 reactions.
10.5 EFFECT OF SUBSTRATE
TABLE 10.2 Relative Rates for Halide Hydrolysis in Water
PROBLEM 10.5
10.6 Substitution versus Elimination
FIGURE 10.23 Competition between SN1 and E1 reactions.
FIGURE 10.24 Competition between substitution and elimination.
FIGURE 10.25 Solvent effects on selectivity between SN2 and E2 reactions.
PROBLEM 10.6
10.7 CARBOCATION REARRANGEMENTS
FIGURE 10.26 Carbocation rearrangement in an E1 elimination.
FIGURE 10.27 Carbocation rearrangement in E1 elimination.
PROBLEM 10.7
FIGURE 10.28 Applications of E1 elimination in synthesis.
Key Points from Sections 10.4 through 10.7
10.8 EXAMPLES AND APPLICATIONS
10.8 1 E1 REACTIONS
10.8.2 E2 REACTIONS
FIGURE 10.29 E2 elimination of HBr.
FIGURE 10.30 Elimination of a tertiary amine.
FIGURE 10.31 Examples of E2 elimination reactions in synthesis.
10.8.3 E1CB Reactions
FIGURE 10.32 E1cB elimination reactions.
10.8.4 MIXED OR VARIABLE MECHANISMS
FIGURE 10.33 Dehydration of a β-hydroxyketone by the E1cB mechanism.
PROBLEM 10.8
10.9 ELIMINATION TO GIVE ALKYNES
FIGURE 10.34 Possible mechanisms of elimination to give alkynes.
FIGURE 10.35 Dehydrohalogenation reactions to produce alkynes.
FIGURE 10.36 Synthesis of alkynes as intermediates in total synthesis.
FIGURE 10.37 Elimination of HBr from bromobenzene to give benzyne.
PROBLEM 10.9
FIGURE 10.38 Some reactions of benzyne.
10.10 OTHER ELIMINATION REACTIONS
FIGURE 10.39 Aqueous equilibria involving Cr(VI).
FIGURE 10.40 Cr(VI) oxidation of alcohols.
FIGURE 10.41 Chromium(VI) oxidation of axial and equatorial alcohols.
PROBLEM 10.10
Focus on Alcohol Oxidation: A Look Ahead
FIGURE 10.42 Oxidation of primary and secondary alcohols using chromium(VI).
Key Points from Sections 10.9 and 10.10
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
11 Addition Reactions
11.1 INTRODUCTION
11.2 ELECTROPHILIC REACTIONS
11.2.1 REACTION MECHANISM
FIGURE 11.1 Mechanism of electrophilic addition of HX to an alkene.
FIGURE 11.2 Addition of HX to a nonsymmetrical alkene.
FIGURE 11.3 Examples of Markovnikov addition.
TABLE 11.1 Relative Rate of Acid-Catalyzed Addition of Water to Alkenes
FIGURE 11.4 Electrophilic addition reactions are rarely stereospecific.
FIGURE 11.5 Intermediate carbocations can be captured by solvent.
FIGURE 11.6 Carbocation rearrangements in addition reactions.
PROBLEM 11.1
PROBLEM 11.2
11.2.2 SCOPE OF THE REACTION
FIGURE 11.7 Addition of HCl or HBr to alkenes.
FIGURE 11.8 Addition of “HF” to an alkene.
FIGURE 11.9 Addition of HX to alkenes is not regioselective when the intermediate cations are of comparable stability.
FIGURE 11.10 Acid-catalyzed addition of water to an alkene.
FIGURE 11.11 Addition of water or alcohols to alkenes.
PROBLEM 11.3
PROBLEM 11.4
FIGURE 11.12 Addition of molecular bromine to cyclopentene.
FIGURE 11.13 SN2 ring opening of epoxides and bromonium ions.
FIGURE 11.14 Addition of halogens to alkenes.
FIGURE 11.15 Addition of chlorine water to an alkene.
FIGURE 11.16 Formation and opening of halonium ions and epoxides fused to cyclohexane rings.
FIGURE 11.17 Regiospecific addition of Br2/MeOH to an alkene.
FIGURE 11.18 Addition of halogens to alkenes in the presence of water or alcohols.
Focus on Halolactonization
FIGURE 11.19 The mechanism of halolactonization.
FIGURE 11.20 Halolactonization in synthesis. Note: Thallium carbonate is acting as a base to deprotonate the acid.
FIGURE 11.21 Halolactonization in the synthesis of erythronolide B.
FIGURE 11.22 Mechanism of the oxymercuration reaction.
FIGURE 11.23 Oxymercuration in synthesis.
FIGURE 11.24 Cationic polymerization of styrene.
PROBLEM 11.5
11.2.3 ELECTROPHILIC ADDITION TO CONJUGATED DIENES
FIGURE 11.25 Addition of chlorine to nonconjugated double bonds.
FIGURE 11.26 Addition of HBr to butadiene at low temperature.
FIGURE 11.27 Addition of HBr to 2,4-hexadiene.
FIGURE 11.28 Addition of chlorine to butadiene.
PROBLEM 11.6
11.2.4 TERPENES: BIOLOGY OLIGOMERIZES DIENES
FIGURE 11.29 Structures of some common monoterpenes.
FIGURE 11.30 Sesquiterpenes, diterpenes, and triterpenes.
FIGURE 11.31 Formation of geranyl diphosphate.
PROBLEM 11.7
11.2.5 ELECTROPHILIC ADDITION TO ALKYNES
FIGURE 11.32 Mechanism of HBr addition to an alkyne.
FIGURE 11.33 Addition of HBr to a bromoalkene.
FIGURE 11.34 Markovnikov rule in addition of HBr to an alkyne.
FIGURE 11.35 Addition of bromine to 2-butyne.
FIGURE 11.36 Alkenes are more reactive than alkynes in addition reactions.
FIGURE 11.37 Addition of water to alkynes.
FIGURE 11.38 Mechanism of mercury-catalyzed addition of water to an alkyne.
PROBLEM 11.8
Key Points from Sections 11.1 and 11.2
11.3 RADICAL ADDITION REACTIONS
FIGURE 11.39 Radical addition of HBr to 2-methyl-2-butene.
FIGURE 11.40 Initiation of HBr addition using dibenzoyl peroxide.
FIGURE 11.41 Radical addition of HBr to an alkene.
FIGURE 11.42 Addition of HBr to Z-1-phenyl-1-propene under radical conditions.
FIGURE 11.43 Other radical additions to alkenes.
FIGURE 11.44 Radical-initiated polymerization of styrene.
FIGURE 11.45 Radical addition to butadiene.
FIGURE 11.46 Radical addition to an alkyne.
PROBLEM 11.9
PROBLEM 11.10
Key Points from Section 11.3
11.4 MULTICENTER PROCESSES
FIGURE 11.47 Synchronous addition of A–B to an alkene.
11.4.1 EPOXIDATION USING PERACIDS
FIGURE 11.48 Mechanism of alkene epoxidation using peracid.
FIGURE 11.49 Peracid-mediated epoxidation of alkenes.
Focus on Sharpless Asymmetric Epoxidation of Allylic Alcohols
FIGURE 11.50 Sharpless asymmetric epoxidation. (a) 2S, 3S (b) 2S, 3R (c) left-hand molecule R, right-hand molecule, S; CH2 OC outranks CH2OH.
11.4.2 CARBENE ADDITION
FIGURE 11.51 Singlet and triplet methylene.
FIGURE 11.52 Generation of methylene.
FIGURE 11.53 Generation and use of a methylene equivalent in the Simmons–Smith reaction.
FIGURE 11.54 Simmons–Smith reactions for cyclopropanation of alkenes.
FIGURE 11.55 Dichlorocarbene is electrophilic and reacts selectively with more electron-rich double bonds.
PROBLEM 11.11
11.4.3 HYDROBORATION
FIGURE 11.56 Addition of borane to cyclohexene.
FIGURE 11.57 Reaction of trialkylborane with hydroperoxide anion.
FIGURE 11.58 Addition of water to 1,2-dimethylcyclohexene.
FIGURE 11.59 Regiospecific addition of water to an alkene under acid catalysis.
FIGURE 11.60 Anti-Markovnikov addition of water via hydroboration–oxidation.
FIGURE 11.61 Hydroboration–oxidation in synthesis.
PROBLEM 11.12
PROBLEM 11.13
Focus on Boranes in Organic Synthesis
FIGURE 11.62 Hydroboration–oxidation of Z-4-methyl-2-pentene.
FIGURE 11.63 Selectivity between double bonds in reaction with a hindered borane.
FIGURE 11.64 Hydroboration of an alkyne.
FIGURE 11.65 Reactions of alkynes with hindered boranes.
FIGURE 11.66 Enantioselective hydroboration using a chiral borane.
11.4.4 DIHYDROXYLATION OF ALKENES
FIGURE 11.67 Synthesis of trans-diols.
FIGURE 11.68 cis-Hydroxylation by osmium tetroxide.
FIGURE 11.69 Catalytic system for the cis-dihydroxylation of alkenes.
FIGURE 11.70 Applications of dihydroxylation reactions in synthesis.
PROBLEM 11.14
Focus on Sharpless Asymmetric Dihydroxylation
FIGURE 11.71 Uses of asymmetric dihydroxylation in synthesis.
11.4.5 OZONOLYSIS
FIGURE 11.72 Reaction of ozone with alkenes to give an ozonide.
FIGURE 11.73 Oxidative and reductive work-ups for ozonides.
FIGURE 11.74 Ozonolysis in synthesis.
PROBLEM 11.15
11.4.6 CYCLOADDITIONS, DIELS–ALDER REACTIONS
FIGURE 11.75 Diels–Alder reaction.
FIGURE 11.76 Practical Diels–Alder reactions.
FIGURE 11.77 Diels–Alder reactions are stereospecific.
FIGURE 11.78 Relative reactivity of dienes with maleic anhydride.
FIGURE 11.79 4 + 2-Cycloadditions occur on heating, but 2 + 2-cycloadditions do not.
FIGURE 11.80 HOMO and LUMO for a simple alkene.
FIGURE 11.81 HOMO + LUMO for a 2 + 2-cycloaddition.
FIGURE 11.82 LUMO + LUMO for a 2 + 2-cycloaddition.
FIGURE 11.83 2 + 2-Cycloadditions.
FIGURE 11.84 Molecular orbitals of butadiene.
FIGURE 11.85 HOMO + LUMO for 4 + 2-cycloaddition.
FIGURE 11.86 Diels–Alder reactions in synthesis.
FIGURE 11.87 The endo-rule in Diels–Alder reactions of cyclic dienes.
FIGURE 11.88 Secondary orbital interactions lead to the endo-rule.
PROBLEM 11.16
Key Points from Section 11.4
11.5 HYDROGENATION
FIGURE 11.89 Hydrogenation of an alkene using a heterogeneous catalyst.
FIGURE 11.90 Mechanism of heterogeneous hydrogenation of alkenes.
FIGURE 11.91 Addition of hydrogen to alkenes in the presence of a heterogeneous catalyst takes place from the less hindered face of the double bond.
FIGURE 11.92 Homogeneous catalysis of hydrogenation by metal complexes.
FIGURE 11.93 Partial reduction of alkynes to cis-alkenes.
FIGURE 11.94 Dissolving metal reduction of alkynes.
PROBLEM 11.17
Focus on Fats: Saturated, Unsaturated, Polyunsaturated, and trans
FIGURE 11.95 Formation of triglycerides.
FIGURE 11.96 C18 fatty acids.
Key Points from Section 11.5
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
12 Electrophilic Aromatic Substitution
12.1 INTRODUCTION
FIGURE 12.1 Addition to carbon–carbon double bond.
FIGURE 12.2 Addition of HX to alkenes.
FIGURE 12.3 Reaction of benzene with an electrophile.
FIGURE 12.4 Electrophilic aromatic substitution. Note: E+ is an electrophile such as H+, Br+ (Br2), [NO2]+, [Me3C]+, [CH3C(=O)]+, etc.
FIGURE 12.5 Mechanism of electrophilic aromatic substitution.
FIGURE 12.6 Alkylation of 1,3,5-trimethylbenzene by fluoroethane in the presence of BF3.
FIGURE 12.7 Resonance forms of a Wheland intermediate.
12.2 ELECTROPHILES
12.2.1 PROTONS
12.2.2 CARBOCATIONS
FIGURE 12.8 Deuteration of benzene.
FIGURE 12.9 Friedel–Crafts alkylation of benzene.
FIGURE 12.10 Mechanism of Friedel–Crafts methylation of benzene.
FIGURE 12.11 Rearrangement of a propyl cation.
FIGURE 12.12 Friedel–Crafts reaction of benzene with 1-chloropropane.
FIGURE 12.13 Friedel–Crafts reaction of 1-chloro-2-methylpropane with benzene.
FIGURE 12.14 Multiple alkylations in the Friedel–Crafts reaction.
FIGURE 12.15 Friedel–Crafts alkylation with a tertiary halide.
FIGURE 12.16 Other methods of generating cations for the Friedel–Crafts reaction.
PROBLEM 12.1
PROBLEM 12.2
FIGURE 12.17 Friedel–Crafts acylation.
FIGURE 12.18 Clemmensen reduction of aryl ketones.
FIGURE 12.19 Gattermann–Koch formylation of benzene.
12.2.3 HALOGENS
Focus on Thermodynamics
TABLE 12.1 Thermodynamic Parameters for Halogen Addition to Benzene
FIGURE 12.20 Bromination of benzene.
FIGURE 12.21 Reaction of nitric acid with sulfuric acid.
FIGURE 12.22 Mechanism of nitration of benzene.
12.2.4 NITRATION
12.2.5 SULFONATION
FIGURE 12.23 Mechanism of sulfonation of benzene.
FIGURE 12.24 Reactions of benzene sulfonic acid.
FIGURE 12.25 Sulfonation of a substituted phenol.
FIGURE 12.26 Sulfonation of naphthalene under thermodynamic and kinetic conditions.
Focus on Biologically Active Phenols
Key Points from Sections 12.1 and 12.2
TABLE 12.2 Reaction of Electrophiles with Benzene
PROBLEM 12.3
PROBLEM 12.4
12.3 ORIENTATION EFFECTS
12.3.1 INDUCTIVE DONORS
FIGURE 12.27 Regiochemistry of nitration of toluene.
FIGURE 12.28 Resonance forms of the Wheland intermediate in electrophilic substitution of toluene at the ortho-position.
FIGURE 12.29 Resonance forms of the Wheland intermediate in electrophilic substitution of toluene at the meta-position.
FIGURE 12.30 Resonance forms of the Wheland intermediate in electrophilic substitution of toluene at the para-position.
FIGURE 12.31 Regiochemistry of toluene substitution.
PROBLEM 12.5
12.3.2 RESONANCE DONORS
FIGURE 12.32 Lone pairs stabilize a positive center.
FIGURE 12.33 Mechanism of electrophilic substitution of an aromatic ring bearing a resonance donor.
FIGURE 12.34 Trisubstitution of phenol by bromine.
PROBLEM 12.6
12.3.3 RESONANCE ACCEPTORS
FIGURE 12.35 Resonance structures of the possible intermediates for the electrophilic substitution of nitrobenzene.
FIGURE 12.36 −CF3 is a meta-directing, inductive withdrawer of electron density.
PROBLEM 12.7
12.3.4 HALOGENS
FIGURE 12.37 Nitration of chlorobenzene.
PROBLEM 12.8
12.3.5 TWO OR MORE GROUPS IN CONFLICT
FIGURE 12.38 Electrophilic substitution of 4-methylphenol.
FIGURE 12.39 Size may influence ortho/para ratios.
TABLE 12.3 Nitration of Alkyl Benzenes
PROBLEM 12.9
12.3.6 PARTIAL RATE FACTORS
FIGURE 12.40 Partial rate factors for nitration of nitrotoluene.
FIGURE 12.41 Partial rate factors for deuteration of anisole.
Focus on Partial Rate Factors
TABLE 12.4 Partial Rate Factors in Electrophilic Substitution
PROBLEM 12.10
Key Points from Section 12.3
12.4 REACTIONS OF POLYCYCLIC AROMATIC COMPOUNDS
FIGURE 12.42 Synthesis of naphthalene.
FIGURE 12.43 Nitration of naphthalene.
FIGURE 12.44 Mechanism and regiochemistry of electrophilic substitution of naphthalene.
FIGURE 12.45 Bromination of anthracene.
FIGURE 12.46 Diels–Alder reaction of anthracene and maleic anhydride.
PROBLEM 12.11
Key Points from Section 12.4
12.5 HETEROCYCLIC AROMATIC COMPOUNDS
12.5.1 PYRIDINE AND RELATED COMPOUNDS
FIGURE 12.47 Pyridine and related heterocycles.
FIGURE 12.48 More pyridine-related heterocycles.
FIGURE 12.49 Biologically important nitrogen-containing heterocyclic compounds.
FIGURE 12.50 Acid/base properties of pyridine and piperidine.
FIGURE 12.51 Reaction of pyridine with methyl iodide or hydrogen peroxide.
FIGURE 12.52 Sulfonation of pyridine.
FIGURE 12.53 Resonance forms of possible intermediates produced in electrophilic substitution of pyridine.
12.5.2 ANALOGUES OF THE CYCLOPENTADIENYL ANION
FIGURE 12.54 Heterocyclic analogues of the cyclopentadienyl anion.
FIGURE 12.55 Indole derivatives and related compounds.
TABLE 12.5 Resonance Energy of Various Heterocyclic Compounds
FIGURE 12.56 Electrophilic substitution of five-ring heterocycles.
FIGURE 12.57 Typical electrophilic substitutions of furan and thiophene.
FIGURE 12.58 Diels–Alder reaction of furan.
Key Points from Section 12.5
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
13 Nucleophilic Aromatic Substitution and Synthesis of Aromatic Compounds
13.1 INTRODUCTION
13.2 UNIMOLECULAR NUCLEOPHILIC SUBSTITUTION OF AROMATIC COMPOUNDS: THE REACTIONS OF DIAZONIUM SALTS WITH SIMPLE NUCLEOPHILES
FIGURE 13.1 Mechanism of formation of a diazo compound.
FIGURE 13.2 Reaction of an aromatic diazonium salt with nucleophiles.
FIGURE 13.3 Nucleophiles that react readily with diazonium salts.
FIGURE 13.4 Synthetic examples of substitution of diazonium salts.
FIGURE 13.5 Sandmeyer reaction.
FIGURE 13.6 Fluorination of an aromatic ring.
Focus on the Sandmeyer Reaction
FIGURE 13.7 Sandmeyer reactions in synthesis.
FIGURE 13.8 Removal of an amino group by diazotization followed by reduction.
PROBLEM 13.1
13.3 AZO COUPLING REACTIONS
FIGURE 13.9 Azo coupling of phenol.
FIGURE 13.10 Synthesis of methyl red by azo coupling.
Focus on Azo Compounds
FIGURE 13.11 Preparation of Orange II.
FIGURE 13.12 Azo compounds used as biological stains.
PROBLEM 13.2
Key Points from Sections 13.1 through 13.3
13.4 Nucleophilic Substitution of Aryl Halides, SN2Ar
FIGURE 13.13 Substitution of chlorobenzene.
FIGURE 13.14 Substitution of a nitrohaloarene.
FIGURE 13.15 Relative rates of reaction of nitrated halobenzenes with methoxide ion.
PROBLEM 13.3
FIGURE 13.16 Resonance forms of a Meisenheimer complex.
FIGURE 13.17 Formation of a stable Meisenheimer complex.
FIGURE 13.18 Selective nucleophilic aromatic substitution.
PROBLEM 13.4
13.5 SUBSTITUTION OF HALOHETEROCYCLES
FIGURE 13.19 Mechanism and selectivity of substitution of halopyridines.
FIGURE 13.20 Substitutions of halopyridines.
FIGURE 13.21 Substitution of 3-halopyridines using microwave heating.
PROBLEM 13.5
13.6 SUBSTITUTION VIA BENZYNE AND RELATED INTERMEDIATES
FIGURE 13.22 Substitution of 4-chlorotoluene via a benzyne intermediate.
FIGURE 13.23 Mechanism of benzyne formation.
FIGURE 13.24 Substitution of 13C-labeled chlorobenzene.
FIGURE 13.25 Regioselectivity in substitution via aryne intermediates.
FIGURE 13.26 Substitution via pyridyne.
PROBLEM 13.6
Key Points from Sections 13.4 through 13.6
13.7 REACTIONS IN SIDE CHAINS OF AROMATIC COMPOUNDS
13.7.1 REACTIONS OF ALKYLBENZENES
FIGURE 13.27 Oxidation of alkylbenzenes.
Focus on the Industrial Synthesis of Phenol
FIGURE 13.28 Preparation of cumene.
FIGURE 13.29 Atmospheric oxidation of cumene to cumene hydroperoxide.
FIGURE 13.30 Acid-catalyzed rearrangement of cumene hydroperoxide.
FIGURE 13.31 Radical chain bromination of a benzylic center.
FIGURE 13.32 Benzylic bromination using N-bromosuccinimide.
FIGURE 13.33 Radical chain bromination in synthesis.
PROBLEM 13.7
13.7.2 REDUCTION OF NITRO GROUPS
FIGURE 13.34 Reduction of nitroaromatic compounds with tin and HCl.
FIGURE 13.35 Use of the different directing effects of the nitro and amino groups in synthesis.
13.7.3 REDUCTION OF ARYL KETONES
FIGURE 13.36 Clemmensen reduction of aryl aldehydes and ketones.
FIGURE 13.37 Hydrogenolysis of aryl ketones.
13.8 REDUCTION OF BENZENE RINGS
FIGURE 13.38 Selective hydrogenation of an alkene in the presence of an aromatic ring.
FIGURE 13.39 Hydrogenation of benzene.
FIGURE 13.40 Mechanism of the Birch reduction.
FIGURE 13.41 Examples of the Birch reduction.
Key Points from Sections 13.7 through 13.8
PROBLEM 13.8
13.9 CARBON–ARYL BOND FORMATION
13.9.1 FRIEDEL–CRAFTS ALKYLATION AND ACYLATION (SEE ALSO SECTION 12.2.2)
FIGURE 13.42 Friedel–Crafts reaction with tert-butyl chloride.
FIGURE 13.43 Alkylation of benzene using tert-butanol.
FIGURE 13.44 Friedel–Crafts acylation of a polycyclic compound.
FIGURE 13.45 Friedel–Crafts formylation.
FIGURE 13.46 Gattermann–Koch formylation of benzene.
PROBLEM 13.9
13.9.2 HALOALKYLATION REACTIONS
FIGURE 13.47 Haloalkylation of benzene.
FIGURE 13.48 Mechanism of chloromethylation of benzene.
FIGURE 13.49 Chloromethylation of polystyrene.
PROBLEM 13.10
13.9.3 REACTIONS OF GRIGNARD REAGENTS
FIGURE 13.50 Key reactions of Grignard reagents.
FIGURE 13.51 Useful reactions of aromatic nitriles.
13.9.4 NUCLEOPHILIC SUBSTITUTION BY CYANIDE
PROBLEM 13.11
Key Points from Section 13.9
13.10 AROMATIC SYNTHESIS
PROBLEM 13.12
PROBLEM 13.13
PROBLEM 13.14
PROBLEM 13.15
PROBLEM 13.16
FIGURE 13.52 Solution to Problem 13.16.
PROBLEM 13.17
FIGURE 13.53 Solution to Problem 13.17.
PROBLEM 13.18
PROBLEM 13.19
FIGURE 13.54 Synthesis of ortho-nitrophenol.
PROBLEM 13.20
FIGURE 13.55 Synthesis of 3-ethylaniline.
PROBLEM 13.21
FIGURE 13.56 Synthesis of 2,4-dinitrophenylhydrazine.
FIGURE 13.57 Solution to Problem 13.22.
PROBLEM 13.22
REVIEW PROBLEMS
MORE CHALLENGING PROBLEMS
14 Addition to Carbon–Heteroatom Double Bonds
14.1 INTRODUCTION AND REVIEW
PROBLEM 14.1
FIGURE 14.1 Chromium(VI) oxidation of primary and secondary alcohols.
FIGURE 14.2 Carbonyl compounds synthesized by addition of water to alkynes (Sia2BH is disiamylborane, IUPAC name bis (1,2-dimethylpropyl)borane. 9-BBN is 9-borabicyclo[3.3.1]nonane).
FIGURE 14.3 Carbonyl compounds synthesized by ozonolysis.
FIGURE 14.4 Friedel–Crafts acylation of arenes to give aryl ketones.
FIGURE 14.5 Resonance forms of aldehydes and ketones.
FIGURE 14.6 Comparison of double bonds in alkenes and aldehydes.
FIGURE 14.7 Comparison of polarity of alkenes and ketones.
Focus on Scent and Flavor
FIGURE 14.8 Some aldehydes used in perfumes.
FIGURE 14.9 Aldehydes important in flavor and aroma of food.
FIGURE 14.10 Ketones important in the fragrance industry.
Key Points from Section 14.1
14.2 MECHANISM OF ADDITION REACTIONS
FIGURE 14.11 Mechanism of addition to a carbonyl group under basic conditions.
FIGURE 14.12 Mechanism of addition to a carbonyl group under acidic conditions.
14.3 REVERSIBLE ADDITION REACTIONS
14.3.1 CYANOHYDRIN FORMATION
FIGURE 14.13 Cyanohydrin formation.
TABLE 14.1 Equilibrium Constants for Cyanohydrin Formation in Aqueous Solution
FIGURE 14.14 Reaction of a ketone with trimethylsilyl cyanide (The 18-crown-6 sequesters potassium, breaking up KCN ion pairs, so that the cyanide acts as a better nucleophile).
FIGURE 14.15 Synthetic applications of cyanohydrin formation.
Focus on Naturally Occurring Cyanohydrins
PROBLEM 14.2
PROBLEM 14.3
14.3.2 HYDRATES, HEMIACETALS, AND ACETALS
FIGURE 14.16 Addition of water to a ketone occurs under acidic or basic conditions.
FIGURE 14.17 Acid- and base-catalyzed formation of hemiacetals.
FIGURE 14.18 Acid- and base-catalyzed formation of hemithioacetals.
TABLE 14.2 Equilibrium Constants and Proportions of Hydrate at Equilibrium for Aldehydes and Ketones
FIGURE 14.19 Exchange of the oxygen atom of acetone with 18O water.
FIGURE 14.20 Cyclization of glucose.
PROBLEM 14.4
14.3.3 ACETALS AND THIOACETALS
FIGURE 14.21 Reactions of a hemiacetal with acid.
FIGURE 14.22 Acetal formation.
FIGURE 14.23 Mechanism of formation of a cyclic acetal.
FIGURE 14.24 Reversible acetal formation.
FIGURE 14.25 Dean–Stark apparatus.
PROBLEM 14.5
FIGURE 14.26 Reduction of ketoesters.
FIGURE 14.27 Use of a cyclic acetal as a protecting group.
PROBLEM 14.6
14.3.4 IMINES, ENAMINES, OXIMES, AND HYDRAZONES
FIGURE 14.28 Mechanism of formation of an unsubstituted imine.
FIGURE 14.29 Mechanism of formation of a substituted imine.
FIGURE 14.30 Imine formation reactions.
FIGURE 14.31 Strecker synthesis of amino acids.
PROBLEM 14.7
PROBLEM 14.8
Focus on Transamination
FIGURE 14.32 Transamination reaction.
FIGURE 14.33 Imine exchange in the transamination process.
FIGURE 14.34 Mechanism of transamination.
FIGURE 14.35 Mechanism of enamine formation.
FIGURE 14.36 Preparation of enamines for use in synthesis.
FIGURE 14.37 Mechanism of oxime formation.
FIGURE 14.38 Oxime formation may be stereoselective.
FIGURE 14.39 Uses of oximes in synthesis.
FIGURE 14.40 Reaction of a ketone with hydrazine.
FIGURE 14.41 Mechanism of reaction of 2,4-dinitrophenylhydrazone with ketones.
FIGURE 14.42 Testing for ketones using dinitrophenylhydrazine.
FIGURE 14.43 Ethanal dinitrophenylhydrazone.
PROBLEM 14.9
Key Points from Sections 14.2 and 14.3
14.4 IRREVERSIBLE ADDITION REACTIONS
14.4.1 REPLACEMENT OF CARBONYL OXYGEN BY HYDROGEN
FIGURE 14.44 Friedel–Crafts alkylation and acylation.
FIGURE 14.45 Mechanism of the Wolff–Kishner reduction.
14.4.2 ADDITION OF HYDRIDE: REDUCTION TO ALCOHOLS OR AMINES
FIGURE 14.46 Uses of the Wolff–Kishner reduction.
FIGURE 14.47 Desulfurization of a thioacetal using Raney nickel.
FIGURE 14.48 Addition of hydride to carbonyl compounds.
FIGURE 14.49 Reduction of acetophenone with lithium aluminum hydride gives a racemic product.
FIGURE 14.50 Diastereomeric reduction products are produced in unequal amounts.
FIGURE 14.51 Hydride reductions of aldehydes and ketones.
FIGURE 14.52 Imine reduction using sodium borohydride.
FIGURE 14.53 Imine reduction using sodium cyanoborohydride.
FIGURE 14.54 Reductive amination using a secondary amine.
FIGURE 14.55 Reduction of cyanides using lithium aluminum hydride.
PROBLEM 14.10
14.4.3 ADDITION OF CARBON NUCLEOPHILES
FIGURE 14.56 Preparation of Grignard and organolithium reagents and their reactions with epoxides.
FIGURE 14.57 Reaction of a Grignard reagent with formaldehyde.
FIGURE 14.58 Reaction of Grignard reagents with aldehydes and ketones.
FIGURE 14.59 Reaction of a Grignard reagent with CO2.
FIGURE 14.60 Reaction of a Grignard reagent with an imine.
FIGURE 14.61 Reaction of a Grignard reagent with a nitrile.
FIGURE 14.62 Mechanism of reaction of Grignard reagents with nitriles.
TABLE 14.3 Reactions of Grignard Reagents, RMgX
FIGURE 14.63 Addition of alkyne anions to aldehydes and ketones.
PROBLEM 14.11
FIGURE 14.64 Oxidation of alcohols.
FIGURE 14.65 Grignard reagent-based syntheses.
PROBLEM 14.12
14.4.4 WITTIG REACTIONS
FIGURE 14.66 Wittig reaction.
FIGURE 14.67 Mechanism of the Wittig reaction.
FIGURE 14.68 Synthetic uses of the Wittig reaction.
PROBLEM 14.13
Key Points from Section 14.4
REVIEW PROBLEMS
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15 Substitution of Carbonyl Compounds: Carboxylic Acids and Their Derivatives
15.1 INTRODUCTION: REVIEW OF NOMENCLATURE
FIGURE 15.1 Nomenclature of carboxylic acids.
PROBLEM 15.1
PROBLEM 15.2
15.2 SUBSTITUTION REACTION
15.2.1 EFFECT OF SUBSTRATE
FIGURE 15.2 Substitution at a carbonyl group.
FIGURE 15.3 Formation of a tetrahedral intermediate is disfavored when conjugation is lost.
FIGURE 15.4 Resonance forms of esters and amides.
Focus on Structures of Carbonyl Compounds
TABLE 15.1 Correlation between Carbon–Oxygen Bond Lengths and IR Stretching Frequencies for CH3C(=O)X
TABLE 15.2 Comparison of C–X Distances in Carbonyl Derivatives
15.2.2 EFFECT OF LEAVING GROUP
FIGURE 15.5 Reaction of an acid chloride with base.
FIGURE 15.6 Availability of reactions depends on the leaving group.
PROBLEM 15.3
Key Points from Sections 15.1 and 15.2
15.3 OXYGEN NUCLEOPHILES
FIGURE 15.7 Hydrolysis of acid chlorides and anhydrides.
FIGURE 15.8 The double-headed arrow.
FIGURE 15.9 Reactions of acid chlorides with alcohols or carboxylic acids.
FIGURE 15.10 Reactions of anhydrides with alcohols or carboxylic acids.
FIGURE 15.11 Ester forming reactions in synthesis.
FIGURE 15.12 Reactions with acid chlorides are sensitive to steric hindrance.
FIGURE 15.13 Base-catalyzed hydrolysis of esters.
FIGURE 15.14 Acid-catalyzed hydrolysis of esters.
FIGURE 15.15 Esterifications and hydrolysis of esters in synthesis.
Focus on Esters: Fruit, Fragrance, and Flavor
TABLE 15.3 Esters Important in Taste and Fragrance
FIGURE 15.16 Mechanism of acid-catalyzed hydrolysis of amides.
FIGURE 15.17 Mechanism of base-catalyzed hydrolysis of unsubstituted amides.
FIGURE 15.18 Practical applications of amide hydrolysis in synthesis.
FIGURE 15.19 Selectivity in nitrile hydrolysis.
FIGURE 15.20 Mechanism of hydrolysis of nitriles.
FIGURE 15.21 Nitrile hydrolysis in synthesis.
Focus on Enantioselective Enzymatic Hydrolysis of Esters and Amides
FIGURE 15.22 Kinetic resolution by ester hydrolysis.
FIGURE 15.23 Kinetic resolution of a binaphthol ester.
FIGURE 15.24 Kinetic resolution of an amide, with recycling.
FIGURE 15.25 Enzymatic desymmetrization.
FIGURE 15.26 Asymmetric synthesis of R-mevalonolactone.
Key Points from Section 15.3
PROBLEM 15.4
PROBLEM 15.5
15.4 NITROGEN NUCLEOPHILES
FIGURE 15.27 Synthesis of amides by reaction of ammonia and amines with acid chlorides.
FIGURE 15.28 Synthesis of amides using anhydrides.
FIGURE 15.29 Synthesis of amides using esters.
PROBLEM 15.6
15.5 SYNTHESIS OF ACID CHLORIDES
FIGURE 15.30 Mechanism of acid chloride synthesis using thionyl chloride.
FIGURE 15.31 Preparation and use of acid chlorides.
FIGURE 15.32 Preparation and use in synthesis of acid chlorides using oxalyl chloride.
FIGURE 15.33 Formation of acid chlorides using PCl5.
PROBLEM 15.7
Key Points from Sections 15.4 and 15.5
15.6 HYDRIDE AS NUCLEOPHILE
FIGURE 15.34 Reaction of lithium aluminum hydride with an ester.
FIGURE 15.35 Reduction of some acid derivatives by lithium aluminum hydride.
FIGURE 15.36 Reduction of esters to aldehydes using DIBAH.
FIGURE 15.37 Reduction of acid chlorides to aldehydes using Li[AlH(O-t-Bu)3].
FIGURE 15.38 Reduction of acid derivatives by borohydride reagents.
FIGURE 15.39 Mechanism of reduction of unsubstituted amides by lithium aluminum hydride.
FIGURE 15.40 Lithium aluminum hydride reduction of substituted amides.
FIGURE 15.41 Amine synthesis from amides.
PROBLEM 15.8
15.7 CARBON NUCLEOPHILES
15.7.1 GRIGNARD REAGENTS
FIGURE 15.42 Reaction of a Grignard reagent with an ester.
FIGURE 15.43 Grignard reactions with acid derivatives.
15.7.2 ORGANOLITHIUM COMPOUNDS
15.7.3 ORGANOCADMIUM COMPOUNDS
FIGURE 15.44 Reactions of organolithium compounds with acid derivatives.
FIGURE 15.45 Preparation and use of an organocadmium compound.
15.7.4 ORGANOZINC COMPOUNDS: THE REFORMATSKII REACTION
FIGURE 15.46 Mechanism of the Reformatskii reaction.
FIGURE 15.47 Examples of Reformatskii reactions in synthesis.
15.7.5 ORGANOCOPPER REAGENTS
FIGURE 15.48 Preparation of organocopper compounds and their reaction with acyl halides.
FIGURE 15.49 Mechanism of reaction of organocopper compounds with acyl halides.
PROBLEM 15.9
Key Points from Sections 15.6 and 15.7
REVIEW PROBLEMS
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16 Lipids and Carbohydrates
16.1 INTRODUCTION
16.2 LIPIDS
16.2.1 SURFACTANTS
FIGURE 16.1 Surfactant molecule.
FIGURE 16.2 Monolayer of a surfactant on water.
FIGURE 16.3 Schematic of a spherical ionic micelle.
FIGURE 16.4 Formation of micelles gives rise to a discontinuity in a plot of physical properties against concentration.
FIGURE 16.5 Bilayer structure of cell membranes.
16.2.2 FATTY ACIDS AND TRIGLYCERIDES
FIGURE 16.6 Schematic representation of a unilamellar vesicle. Note: Unilamellar means single walled; vesicles can form more complex structures with one inside another.
FIGURE 16.7 Hydrolysis of triglycerides.
TABLE 16.1 Common Saturated Fatty Acids
TABLE 16.2 Unsaturated Fatty Acids
PROBLEM 16.1
16.2.3 PROSTAGLANDINS
FIGURE 16.8 Prostaglandin biosynthesis.
TABLE 16.3 Uses of Prostaglandins
PROBLEM 16.2
16.2.4 WAXES
TABLE 16.4 Naturally Occurring Waxes
PROBLEM 16.3
16.2.5 STEROIDS
FIGURE 16.9 Biosynthesis of lanosterol in mammals and fungi.
FIGURE 16.10 Conversion of testosterone to estradiol.
TABLE 16.5 Uses and Functions of Steroid Hormones
FIGURE 16.11 Plant-derived steroids.
Focus on Anabolic Steroids in Sport
Key Points from Section 16.2
PROBLEM 16.4
16.3 CARBOHYDRATES
16.3.1 INTRODUCTION
16.3.2 TRIOSE SUGARS
Quick Review of the Fischer Projections
PROBLEM 16.5
16.3.3 TETROSE SUGARS
16.3.4 PENTOSE SUGARS
FIGURE 16.12 Structures of the D-aldopentoses.
16.3.5 HEXOSE SUGARS
FIGURE 16.13 Sugar family tree.
PROBLEM 16.6
16.3.6 CYCLIC FORMS OF SUGARS
FIGURE 16.14 Cyclization of ribose.
FIGURE 16.15 Pyranose forms of glucose.
FIGURE 16.16 Mechanism of mutarotation of glucose.
PROBLEM 16.7
16.3.7 SUBSTITUTION OF THE OH GROUPS OF SUGARS
FIGURE 16.17 Substitution reactions by the hydroxyl groups of sugars.
FIGURE 16.18 Mechanism of formation of methyl glycosides.
FIGURE 16.19 Morphine and heroin metabolites.
PROBLEM 16.8
16.3.8 OXIDATION REACTIONS
FIGURE 16.20 Mild oxidation of glucose to gluconic acid.
FIGURE 16.21 Tollens’ test for a “reducing” sugar.
FIGURE 16.22 Redox reactions in the oxidation of aldose sugars to aldonic acids.
FIGURE 16.23 Fehling’s test for a reducing sugar.
FIGURE 16.24 Silver(I) oxidation of fructose.
FIGURE 16.25 Oxidation of glucose by bromine.
FIGURE 16.26 Cyclization of gluconic acids.
FIGURE 16.27 Vigorous oxidation of glucose.
FIGURE 16.28 Oxidation of allose and galactose.
PROBLEM 16.9
FIGURE 16.29 Borohydride reduction of glucose.
16.3.9 REDUCTION
16.3.10 CHAIN LENGTHENING AND SHORTENING REACTIONS
FIGURE 16.30 Killani–Fischer chain extension of ribose.
FIGURE 16.31 Wohl degradation of glucose to arabinose.
FIGURE 16.32 Ruff degradation of mannose.
PROBLEM 16.10
Focus on the Determination of the Configuration of Glucose
16.3.11 DISACCHARIDES
FIGURE 16.33 Methylation and hydrolysis of sucrose.
PROBLEM 16.11
Focus: Sweets for My Sweet, Sugar for My Honey
TABLE 16.6 Relative Sweetness of Various Nutritive and Nonnutritive Sweeteners
FIGURE 16.34 Structures of some nonsugar sweeteners.
16.3.12 POLYSACCHARIDES
FIGURE 16.35 Three-dimensional helical structure of amylose.
Key Points from Section 16.3
REVIEW PROBLEMS
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17 Substitution α and β to Carbonyl Groups
17.1 INTRODUCTION
17.2 FORMATION OF ENOLS AND ENOLATES
FIGURE 17.1 Thought experiment in making enols.
FIGURE 17.2 Base-catalyzed formation of enols.
FIGURE 17.3 Acid-catalyzed formation of enols.
FIGURE 17.4 Acid/base equilibrium of enols and enolates.
FIGURE 17.5 Nonenolizable carbonyl compounds.
FIGURE 17.6 Mechanism of H/D exchange in acetaldehyde.
PROBLEM 17.1
Focus on NMR Spectroscopy of Enols
FIGURE 17.7 Proton NMR chemical shifts of keto and enol forms of pentane-2,4-dione.
FIGURE 17.8 Proton NMR spectroscopic data for dimedone in CDCl3.
FIGURE 17.9 Enolization of a fluorinated β-dicarbonyl compound.
17.3 ISOMERIZATIONS INVOLVING ENOLS AND ENOLATES
FIGURE 17.10 Isomerization of an α-hydroxyaldehyde.
FIGURE 17.11 Interconversion of glucose, fructose, and mannose.
PROBLEM 17.2
FIGURE 17.12 Reprotonation of a dienolate.
PROBLEM 17.3
FIGURE 17.13 cis/trans-Isomerization as a result of enolization.
Key Points from Sections 17.1 through 17.3
17.4 REACTIONS OF ENOLS AND ENOLATES WITH ELECTROPHILES
17.4.1 REACTION WITH HALOGENS
FIGURE 17.14 Bromination of acetone.
FIGURE 17.15 Mechanism of bromination of acetaldehyde under acidic or basic conditions.
FIGURE 17.16 Bromination of enols/enolates in synthesis.
PROBLEM 17.4
FIGURE 17.17 Iodoform reaction.
FIGURE 17.18 Iodoform reaction.
FIGURE 17.19 Iodoform reaction in synthesis.
PROBLEM 17.5
FIGURE 17.20 Halogenation of a nonsymmetric ketone under acid catalysis.
FIGURE 17.21 Hell–Volhard–Zelinsky reaction.
FIGURE 17.22 Examples of the Hell–Volhard–Zelinsky reaction.
FIGURE 17.23 Hell–Volhard–Zelinsky and Reformatskii reactions.
PROBLEM 17.6
PROBLEM 17.7
Key Points from Section 17.4.1
17.4.2 ALDOL REACTION
FIGURE 17.24 Aldol reaction of acetaldehyde.
FIGURE 17.25 Aldol reaction of acetone.
FIGURE 17.26 Soxhlet apparatus for aldol condensation.
FIGURE 17.27 Self-condensations of aldehydes and ketones.
FIGURE 17.28 Cross condensation of acetone and acetophenone.
FIGURE 17.29 Cross condensation of acetophenone and 4-chlorobenzaldehyde.
FIGURE 17.30 Intramolecular aldol condensations.
FIGURE 17.31 Intramolecular aldol condensation in steroid synthesis.
PROBLEM 17.8
PROBLEM 17.9
17.4.3 CLAISEN ESTER CONDENSATION
FIGURE 17.32 Claisen ester condensation of ethyl acetate.
PROBLEM 17.10
FIGURE 17.33 Dieckmann condensation.
FIGURE 17.34 Application of the Dieckmann condensation.
FIGURE 17.35 Crossed Claisen condensations.
Key Points from Sections 17.4.3 and 17.4.4
TABLE 17.1 Important Condensation Reactions
PROBLEM 17.11
Focus on Biological Claisen Condensations: Synthesis of Fatty Acids and Polyketides
FIGURE 17.36 Claisen condensation of acetyl CoA.
FIGURE 17.37 Alkylation of diethyl malonate.
FIGURE 17.38 Decarboxylation of β-carbonyl acids.
17.4.4 ALKYLATION OF β-DICARBONYL COMPOUNDS
PROBLEM 17.12
FIGURE 17.39 Ethyl acetoacetate and diethyl malonate in synthesis.
FIGURE 17.40 Alkylation of a β-diketone.
FIGURE 17.41 Thallium ethoxide in alkylation of a β-diketone.
PROBLEM 17.13
17.4.5 ALKYLATION OF SIMPLE KETONES
FIGURE 17.42 Deprotonation of 2-methylcyclohexanone.
TABLE 17.2 Formation of Enolates from 2-Methylcyclohexanone
FIGURE 17.43 Formation of polyalkylated products from enolate alkylation.
FIGURE 17.44 Selective alkylation of cyclohexanone.
FIGURE 17.45 Alkylation of carbonyl compounds.
PROBLEM 17.14
Focus on Enolate Structure
Focus on Silyl Enol Ethers
FIGURE 17.46 Formation and reaction of silyl enol ethers.
FIGURE 17.47 Regioselective alkylation of methylcyclohexanone, via silyl enol ethers.
FIGURE 17.48 Reaction of a silyl enol ether with a tertiary halide.
FIGURE 17.49 Examples of the Mukaiyama aldol reaction.
17.4.6 REACTIONS OF ENAMINES
PROBLEM 17.15
FIGURE 17.50 Enamine preparation.
FIGURE 17.51 Selectivity in enamine reactions.
PROBLEM 17.16
FIGURE 17.52 Reformatskii reaction.
FIGURE 17.53 Reformatskii reagent considered as an ester enolate.
17.4.7 REVISITING THE REFORMATSKII REACTION
PROBLEM 17.17
17.5 TWO USEFUL REACTIONS OF NONENOLIZABLE CARBONYL COMPOUNDS
FIGURE 17.54 Benzoin condensation.
FIGURE 17.55 Cannizzaro reaction of benzaldehyde.
FIGURE 17.56 Cross Cannizzaro reaction using formaldehyde.
Key Points from Sections 17.4.4 through 17.5
17.6 REACTIONS AT THE β-POSITION OF α,β-UNSATURATED CARBONYL COMPOUNDS AND OTHER ELECTRON-POOR ALKENES
17.6.1 REACTIONS OF ENONES WITH SIMPLE NUCLEOPHILES
FIGURE 17.57 Addition of cyanide to an enone.
FIGURE 17.58 Reversible cyanohydrin formation from an enone.
FIGURE 17.59 Addition of simple nucleophiles to enones.
PROBLEM 17.18
FIGURE 17.60 Conjugate addition to alkenes bearing other electron-accepting groups.
17.6.2 CONJUGATE ADDITION TO OTHER ELECTRON-POOR ALKENES
17.6.3 EPOXIDATION OF ELECTRON-POOR ALKENES
FIGURE 17.61 Epoxidation of enones with alkaline hydrogen peroxide.
FIGURE 17.62 Selectivity in epoxidation reactions.
PROBLEM 17.19
17.6.4 ORGANOMETALLIC NUCLEOPHILES
FIGURE 17.63 1,2-Addition of a Grignard reagent to an unsaturated aldehyde.
FIGURE 17.64 Conjugate addition of a Grignard reagent to an unsaturated carbonyl compound in the presence of copper(I) salts.
FIGURE 17.65 Mechanisms for addition of organocopper reagents to enones.
FIGURE 17.66 Conjugate addition of organocopper reagents in synthesis.
PROBLEM 17.20
17.6.5 ADDITION OF ENOLATE ANIONS TO ENONES
FIGURE 17.67 Addition of diethyl malonate to an enone.
FIGURE 17.68 Reaction of an unstabilized enolate with an enal.
FIGURE 17.69 Mechanism of addition of a stabilized anion to an enone.
FIGURE 17.70 Addition of enols/enolates to α,β-unsaturated carbonyl compounds and related processes.
17.6.6 ROBINSON ANNULATION: A LOOK AHEAD TO SYNTHESIS
FIGURE 17.71 Mechanism of reaction of enamines with enones.
FIGURE 17.72 Mechanism of the Robinson annulation.
FIGURE 17.73 Robinson annulations in synthesis.
Key Points from Section 17.6
FIGURE 17.74 Robinson annulation using an enamine starting reagent.
REVIEW PROBLEMS
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18 Rearrangement Reactions
18.1 INTRODUCTION
18.2 MIGRATION TO ELECTRON-DEFICIENT CARBON
18.2.1 CARBOCATION REARRANGEMENTS
FIGURE 18.1 Review of carbocation rearrangements.
FIGURE 18.2 Mechanism of a carbocation rearrangement.
PROBLEM 18.1
FIGURE 18.3 Migration of phenyl group via a phenonium ion.
PROBLEM 18.2
18.2.2 PINACOL AND SEMIPINACOL REARRANGEMENTS
FIGURE 18.4 Pinacol rearrangement.
FIGURE 18.5 Selectivity in the pinacol rearrangement.
FIGURE 18.6 Selectivity in pinacol rearrangements.
FIGURE 18.7 Semipinacol or Tiffeneau–Demjanov rearrangement.
PROBLEM 18.3
FIGURE 18.8 Stereoelectronic control in the semipinacol rearrangement.
FIGURE 18.9 Ring expansion using the semipinacol reaction.
PROBLEM 18.4
18.2.3 DIENONE–PHENOL REARRANGEMENTS
FIGURE 18.10 Mechanism of the dienone–phenol rearrangement.
FIGURE 18.11 Dienone–phenol rearrangements.
PROBLEM 18.5
Focus on the Norbornyl Cation
FIGURE 18.12 Rearrangement in the bornyl system.
FIGURE 18.13 Rearrangements in the norbornyl system.
FIGURE 18.14 Proposed structures for the norbornyl cation.
FIGURE 18.15 Reaction of the norbornyl cation with acetate.
18.3 MIGRATION TO ELECTRON-DEFICIENT NITROGEN
18.3.1 BECKMANN REARRANGEMENT
FIGURE 18.16 Mechanism of the Beckmann rearrangement.
FIGURE 18.17 Beckmann rearrangements are stereospecific.
PROBLEM 18.6
18.3.2 HOFMANN DEGRADATION: A CHAIN-SHORTENING REACTION
FIGURE 18.18 Mechanism of the Hofmann degradation.
FIGURE 18.19 Examples of the Hofmann degradation.
PROBLEM 18.7
18.4 MIGRATION TO ELECTRON-DEFICIENT OXYGEN: THE BAEYER–VILLIGER OXIDATION
FIGURE 18.20 Baeyer–Villiger oxidation.
FIGURE 18.21 Examples of the Baeyer–Villiger reaction.
PROBLEM 18.8
Key Points from Sections 18.2 through 18.4
18.5 ANIONIC REARRANGEMENTS
FIGURE 18.22 Mechanism of the benzylic acid rearrangement.
FIGURE 18.23 Benzylic acid-type rearrangement of a 1,2-diketone.
FIGURE 18.24 Mechanism of the Favorskii rearrangement.
FIGURE 18.25 Favorskii/semibenzylic acid rearrangement.
FIGURE 18.26 Examples of the Favorskii rearrangement.
PROBLEM 18.9
PROBLEM 18.10
Key Points from Section 18.5
18.6 NEUTRAL REARRANGEMENTS
18.6.1 ELECTROCYCLIC REACTIONS
FIGURE 18.27 Electrocyclic reactions.
FIGURE 18.28 HOMO of butadiene.
FIGURE 18.29 Thermal electrocyclic ring closures of substituted butadienes.
FIGURE 18.30 HOMO of hexatriene.
FIGURE 18.31 Thermal electrocyclic ring closure of substituted hexatrienes.
FIGURE 18.32 LUMO of butadiene.
FIGURE 18.33 Photochemical electrocyclic ring closures of substituted butadienes.
TABLE 18.1 Stereochemical Outcomes of Electrocyclic Reactions
FIGURE 18.34 Examples of electrocyclic reactions.
PROBLEM 18.11
18.6.2 SIGMATROPIC REARRANGEMENTS
FIGURE 18.35 Cope rearrangement, a 3,3-sigmatropic process.
FIGURE 18.36 1,5-Hydride shift.
FIGURE 18.37 1,3-Sigmatropic hydride shift.
FIGURE 18.38 1,5-Sigmatropic hydride shift.
FIGURE 18.39 1,5-Sigmatropic hydride shifts.
FIGURE 18.40 1,3-Carbon sigmatropic shift with inversion of configuration.
FIGURE 18.41 1,5-Carbon sigmatropic shift with retention of configuration.
FIGURE 18.42 Cope rearrangements.
FIGURE 18.43 Examples of the Cope reaction.
FIGURE 18.44 Examples of the oxa-Cope rearrangement.
FIGURE 18.45 Claisen rearrangement.
FIGURE 18.46 Para-Claisen rearrangement.
FIGURE 18.47 Claisen rearrangement of an allyl ether.
PROBLEM 18.12
Focus on Vitamin D
FIGURE 18.48 Biosynthesis of the D vitamins.
Key Points from Section 18.6
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19 Synthesis 1: One-Group Disconnections
19.1 INTRODUCTION
19.2 SIMPLE DISCONNECTIONS AND THE RETROSYNTHETIC APPROACH
FIGURE 19.1 The concept of a synthon.
FIGURE 19.2 Synthesis of 2-phenylethylamine.
FIGURE 19.3 Disconnection and synthesis of tert-butanol.
FIGURE 19.4 Not all disconnections give sensible results.
19.3 ONE-GROUP DISCONNECTIONS
19.3.1 DISCONNECTION OF ALCOHOLS
FIGURE 19.5 Disconnections of cycloalkanols.
FIGURE 19.6 Disconnections of a tertiary alcohol.
PROBLEM 19.1
FIGURE 19.7 Disconnection of tertiary alcohols of type R12 R2COH.
PROBLEM 19.2
FIGURE 19.8 Disconnection of primary alcohols to aldehydes or esters.
PROBLEM 19.3
PROBLEM 19.4
FIGURE 19.9 Additions to alkenes to yield alcohols.
PROBLEM 19.5
TABLE 19.1 Simple Conversions of Alcohols
Key Points from Section 19.3.1
19.3.2 DISCONNECTIONS OF ALKENES
PROBLEM 19.6
FIGURE 19.10 Stereospecific reductions of alkynes.
FIGURE 19.11 Disconnection of alkenes via an alkyne.
PROBLEM 19.7
FIGURE 19.12 Mechanism of the Wittig reaction.
FIGURE 19.13 Examples of the Wittig reaction in synthesis.
PROBLEM 19.8
FIGURE 19.14 Stereochemistry of the Wittig reaction.
PROBLEM 19.9
Focus on the Horner–Wadsworth–Emmons Reaction
FIGURE 19.15 Mechanism of the Arbuzov reaction.
FIGURE 19.16 Uses of the Horner–Wadsworth–Emmons process in synthesis.
FIGURE 19.17 Still–Gennari modification of the HWE reaction.
Key Points from Section 19.3.2
19.3.3 FGIs AND DISCONNECTIONS LEADING TO ALDEHYDES AND KETONES
FIGURE 19.18 Aldehydes and ketones by oxidation of alcohols using chromium oxidants.
PROBLEM 19.10
FIGURE 19.19 Mechanism of the Swern oxidation.
FIGURE 19.20 Examples of the Swern oxidation.
FIGURE 19.21 Preparation of ketones and aldehydes from alkynes.
PROBLEM 19.11
FIGURE 19.22 Reduction of esters to aldehydes.
FIGURE 19.23 Reduction of acid chlorides to aldehydes.
FIGURE 19.24 Reduction of nitriles to aldehydes.
FIGURE 19.25 Rosenmund reduction of acid chlorides.
PROBLEM 19.12
FIGURE 19.26 Reactions of dialkylcopper lithium reagents with acyl halides.
FIGURE 19.27 Synthesis of ketones from nitriles.
FIGURE 19.28 Ketones from organolithium reagents and carboxylic acids.
PROBLEM 19.13
FIGURE 19.29 Synthesis of aryl ketones using the Friedel–Crafts reaction.
FIGURE 19.30 Formylation of aromatic rings.
FIGURE 19.31 Mechanism of the Vilsmeier–Haack formylation.
PROBLEM 19.14
Focus on Dithianes
FIGURE 19.32 Preparation and reactions of dithianes.
FIGURE 19.33 Removal of sulfur from dithianes.
FIGURE 19.34 Oxidation of primary alcohols to carboxylic acids.
19.3.4 FGIs AND DISCONNECTIONS TO PREPARE CARBOXYLIC ACIDS
PROBLEM 19.15
FIGURE 19.35 Oxidation of aldehydes to carboxylic acids.
FIGURE 19.36 Oxidation of alkylarenes to aromatic carboxylic acids.
FIGURE 19.37 Preparation of 13C-labeled benzoic acid.
FIGURE 19.38 Preparation of carboxylic acids by carboxylation of Grignard reagents.
FIGURE 19.39 Synthesis of carboxylic acids via cyanides.
PROBLEM 19.16
Key FGIs from Sections 19.3.3 and 19.3.4
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20 Synthesis 2: Two-Group Disconnections and Protecting Groups
20.1 INTRODUCTION TO TWO-GROUP DISCONNECTIONS
20.2 1,2-DIFUNCTIONALIZED COMPOUNDS
20.2.1 ADDITION TO DOUBLE BONDS
20.2.2 ACYL ANION EQUIVALENTS
FIGURE 20.1 Synthesis of 1,2-diols and amino alcohols.
FIGURE 20.2 Mechanism of cyanohydrin formation using Me3SiCN.
FIGURE 20.3 Uses of cyanohydrins in synthesis of 1,2-difunctionalized compounds.
FIGURE 20.4 The Benzoin condensation.
FIGURE 20.5 Applications of the benzoin and related reactions in synthesis.
FIGURE 20.6 Alkynyl anions as acyl anion equivalents.
FIGURE 20.7 Use of dithianes as acyl anion equivalents (umpolung).
FIGURE 20.8 Mechanism of the pinacol coupling reaction.
20.2.3 RADICAL COUPLING REACTIONS
20.2.4 OTHER REACTIONS
FIGURE 20.9 Applications of the pinacol coupling reaction.
FIGURE 20.10 Mechanism of the acyloin condensation.
FIGURE 20.11 Applications of the acyloin condensation.
FIGURE 20.12 Halogenation α to carbonyl groups.
PROBLEM 20.1
PROBLEM 20.2
PROBLEM 20.3
Key Points from Section 20.2
20.3 1,3-DIFUNCTIONALIZED COMPOUNDS
20.3.1 β-HYDROXYKETONES: THE ALDOL CONDENSATION
FIGURE 20.13 Aldol self-condensations.
FIGURE 20.14 Intramolecular aldol reactions are usually selective.
FIGURE 20.15 Intramolecular aldol reactions in synthesis.
PROBLEM 20.4
FIGURE 20.16 Nonenolizable carbonyl compounds.
FIGURE 20.17 Aldol reactions with nonenolizable components.
PROBLEM 20.5
FIGURE 20.18 Reaction of ethyl acetoacetate with an aldehyde.
PROBLEM 20.6
20.3.2 α,β-UNSATURATED ALDEHYDES AND KETONES
FIGURE 20.19 Synthesis of enals and enones by aldol condensation.
FIGURE 20.20 Disconnection of an enone.
FIGURE 20.21 Disconnection of cyclic enones.
PROBLEM 20.7
20.3.3 1,3-DIKETONES
20.3.4 β-KETOESTERS
FIGURE 20.22 Crossed Claisen condensation to prepare 1,3-diketones.
FIGURE 20.23 Crossed Claisen condensation in synthesis.
FIGURE 20.24 Synthesis of β-ketoesters.
FIGURE 20.25 Reformatskii reaction.
FIGURE 20.26 Use of diethylmalonate in condensation reactions.
20.3.5 TWO IMPORTANT SYNTHONS FOR ESTER ENOLATES
PROBLEM 20.8
Key Points from Section 20.3
20.4 1,4-DIFUNCTIONALIZED COMPOUNDS
FIGURE 20.27 Disconnection of 1,4-dicarbonyl compounds.
FIGURE 20.28 Mechanism of the Darzens condensation.
FIGURE 20.29 Enamines in the synthesis of 1,4-difunctionalized compounds.
PROBLEM 20.9
FIGURE 20.30 Addition of cyanide to enones.
FIGURE 20.31 Conjugate additions of dithianes.
FIGURE 20.32 1,4-Difunctionalized compounds from alkynes.
PROBLEM 20.10
Key Points from Section 20.4
20.5 1,5-DIFUNCTIONALIZED COMPOUNDS
FIGURE 20.33 Disconnection of 1,5-dicarbonyl compounds.
FIGURE 20.34 Reaction of diethyl malonate with cyclohexenone.
FIGURE 20.35 Preparation of 1,5-dicarbonyl compounds and related molecules.
FIGURE 20.36 The Mannich reaction.
PROBLEM 20.11
20.6 ROBINSON ANNULATION
PROBLEM 20.12
Key Points from Sections 20.5 and 20.6
20.7 1,6-DIFUNCTIONALIZED COMPOUNDS
FIGURE 20.37 Ozonolysis of cyclohexene.
FIGURE 20.38 Ozonolysis in synthesis.
FIGURE 20.39 1,6-Difunctionalized compounds by diol cleavage.
PROBLEM 20.13
20.8 PERICYCLIC DISCONNECTIONS
FIGURE 20.40 Stereochemistry of the Diels–Alder reaction.
FIGURE 20.41 Pericyclic disconnections.
FIGURE 20.42 Reaction of the Danishefsky diene.
PROBLEM 20.14
Key Points from Sections 20.7 and 20.8
20.9 PROTECTING GROUPS
20.9.1 PROTECTION OF ALDEHYDES AND KETONES
FIGURE 20.43 Protection of a ketone.
FIGURE 20.44 Selective protection of ketones.
FIGURE 20.45 Reactions of protected aldehydes and ketones.
PROBLEM 20.15
PROBLEM 20.16
20.9.2 PROTECTION OF ALCOHOLS
FIGURE 20.46 Protection of alcohols as THP or MEM derivatives.
FIGURE 20.47 Uses of protected alcohols.
20.9.3 PROTECTION OF 1,2- AND 1,3-DIOLS
FIGURE 20.48 Selective reactions of silyl ethers.
FIGURE 20.49 Protection of diols.
PROBLEM 20.17
PROBLEM 20.18
20.9.4 PROTECTION OF CARBOXYLIC ACIDS
FIGURE 20.50 Formation and hydrolysis of tert-butyl esters.
FIGURE 20.51 Cleavage of benzyl and trichloroethyl esters.
FIGURE 20.52 Formation and cleavage of 2-(trimethylsilyl)ethyl esters.
20.9.5 PROTECTION OF AMINES
TABLE 20.1 Key Protecting Groups from Section 20.9
PROBLEM 20.19
FURTHER READING
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21 Polymeric Materials
21.1 INTRODUCTION
21.2 POLYMER STRUCTURES
TABLE 21.1 Important Definitions in Polymer Chemistry
FIGURE 21.1 Cross-linking of polystyrene.
FIGURE 21.2 Vulcanization of rubber.
FIGURE 21.3 Synthesis of a simple dendrimer.
PROBLEM 21.1
PROBLEM 21.2
Key Points from Section 21.2
21.3 PREPARATION OF ADDITION OR CHAIN-GROWTH POLYMERS
21.3.1 RADICAL POLYMERIZATION
FIGURE 21.4 Thermal decomposition of dibenzoyl peroxide.
FIGURE 21.5 Radical-initiated polymerization of styrene.
FIGURE 21.6 Termination of radical polymerization by disproportionation.
PROBLEM 21.3
FIGURE 21.7 Cationic polymerization of 2-methylpropene (isobutene).
21.3.2 CATIONIC POLYMERIZATION
PROBLEM 21.4
21.3.3 ANIONIC POLYMERIZATION
FIGURE 21.8 Anionic polymerization of methyl acrylate.
PROBLEM 21.5
21.3.4 METAL-MEDIATED POLYMERIZATIONS
FIGURE 21.9 Ziegler–Natta polymerization.
21.3.5 SCOPE OF POLYMERIZATION OF SUBSTITUTED ALKENES
TABLE 21.2 Polymers of Alkenes without Polar Groups
TABLE 21.3 Polymers of Alkenes with Polar Substituents
PROBLEM 21.6
PROBLEM 21.7
Focus on Polymethyl Methacrylate
21.3.6 POLYMERIZATION OF DIENES
FIGURE 21.10 Natural rubber production.
FIGURE 21.11 Polymerization of chloroprene.
FIGURE 21.12 Radical-initiated polymerization of butadiene.
PROBLEM 21.8
21.3.7 RING-OPENING POLYMERIZATION
FIGURE 21.13 Polymerization of ethene oxide.
FIGURE 21.14 Cationic polymerization of THF.
FIGURE 21.15 Polymerization of formaldehyde (methanal).
PROBLEM 21.9
FIGURE 21.16 Polymerization of caprolactone.
FIGURE 21.17 Preparation of nylon 6.
Key Points from Section 21.3
21.4 PREPARATION OF STEP-REACTION POLYMERS
21.4.1 POLYESTERS AND POLYCARBONATES
FIGURE 21.18 Formation of PET.
FIGURE 21.19 Transesterification in Mylar production.
FIGURE 21.20 Synthesis of polycarbonate.
PROBLEM 21.10
PROBLEM 21.11
21.4.2 POLYAMIDES
FIGURE 21.21 Preparation of nylon 6,6.
FIGURE 21.22 Hydrogen bonding in nylon 6,6.
FIGURE 21.23 Preparation of Kevlar.
FIGURE 21.24 Interchain hydrogen bonding in PPTA.
PROBLEM 21.12
PROBLEM 21.13
21.4.3 OTHER POLYMERS
FIGURE 21.25 Mechanism of preparation of polyurethanes.
FIGURE 21.26 Preparation of a commonly used polyurethane.
FIGURE 21.27 Polymer synthesis involving opening of strained rings.
FIGURE 21.28 Polymer synthesis involving SN2 reactions.
PROBLEM 21.14
Key Points from Sections 21.4 and 21.5
21.5 UNUSUAL BIOPOLYMERS
21.5.1 IT’s A STICKY BUSINESS…
21.5.2 CHEWING IT OVER…
21.5.3 PRETTY AS A PICTURE…
FIGURE 21.29 Terpenes found in copal.
FIGURE 21.30 Some of the hydroxyacids found in shellac.
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22 Amines, Alkaloids, Amino Acids, Peptides, and Nucleic Acids
22.1 SYNTHESIS OF AMINES
22.1.1 SYNTHESES INVOLVING NUCLEOPHILIC SUBSTITUTION
FIGURE 22.1 Reaction of ammonia with iodoethane.
FIGURE 22.2 Nucleophilic substitution in a synthesis of a cyclic amine.
FIGURE 22.3 Amine synthesis by ring opening of a hindered epoxide.
FIGURE 22.4 Amino acid synthesis by nucleophilic substitution.
FIGURE 22.5 Amine synthesis by azide reduction.
FIGURE 22.6 Amine synthesis using hexamethylenetetramine.
FIGURE 22.7 Gabriel synthesis of amines.
FIGURE 22.8 Amine synthesis using cyanide.
PROBLEM 22.1
22.1.2 SYNTHESES FROM AMIDES
FIGURE 22.9 Synthesis of amines from amides.
FIGURE 22.10 Synthesis of amides via the Beckmann rearrangement.
FIGURE 22.11 Synthesis of amines from amides using the Hofmann degradation.
FIGURE 22.12 Mechanism of Hofmann degradation using PhI{OC(O)CF3}2.
PROBLEM 22.2
22.1.3 REDUCTION AND ADDITION AT CARBON–NITROGEN DOUBLE BONDS
FIGURE 22.13 Syntheses of amines via imines.
FIGURE 22.14 Examples of amine synthesis from imines.
FIGURE 22.15 Reductive amination of ketones.
PROBLEM 22.3
22.1.4 REDUCTION OF NITRO COMPOUNDS
FIGURE 22.16 Synthesis of arylamines by reduction of nitro groups.
FIGURE 22.17 Reduction of aliphatic nitro compounds to amines.
PROBLEM 22.4
Key Points from Section 22.1
22.2 ALKALOIDS
PROBLEM 22.5
PROBLEM 22.6
22.3 AMINO ACIDS
TABLE 22.1 Common Proteinogenic Amino Acids
22.3.1 SYNTHESIS OF AMINO ACIDS
FIGURE 22.18 Synthesis of amino acids.
FIGURE 22.19 Gabriel synthesis of amino acids.
FIGURE 22.20 Strecker synthesis of amino acids.
FIGURE 22.21 Azlactone synthesis of a dehydroamino acid derivative.
PROBLEM 22.7
22.3.2 RESOLUTION OF AMINO ACIDS
FIGURE 22.22 Amino acid acylation.
FIGURE 22.23 Enzymatic resolution/recycling of amino acid amides.
22.3.3 REACTIONS OF AMINO ACIDS
FIGURE 22.24 Acylation of amino acids.
FIGURE 22.25 Diazotization of an amino acid.
FIGURE 22.26 Reactions of the carboxylate group of amino acids.
FIGURE 22.27 Amino acid reduction in the synthesis of S-tert-BuPHOX. This is a chiral ligand used in a number of enantioselective metal catalysed processes.
PROBLEM 22.8
PROBLEM 22.9
Key Points from Sections 22.2 and 22.3
22.4 PEPTIDES
22.4.1 STRUCTURES OF PEPTIDES AND PROTEINS
FIGURE 22.28 Schematic of a β-pleated sheet for polyalanine.
FIGURE 22.29 (a) Side view of a peptide α-helix. (b) Top down view of a peptide α-helix.
22.4.2 SYNTHESIS
FIGURE 22.30 Preparation of Merrifield resin.
FIGURE 22.31 Protection of the amino groups of amino acids.
FIGURE 22.32 Coupling of a protected amino acid to the resin support.
FIGURE 22.33 Deprotection of the amino group.
FIGURE 22.34 Coupling of peptides with DCC.
PROBLEM 22.10
22.4.3 ANALYSIS OF PEPTIDES
FIGURE 22.35 Sanger method for N-terminus determination in peptides.
FIGURE 22.36 Reaction of a peptide with the Edman reagent.
TABLE 22.2 Reagents for Selective Cleavage of Peptide Chains
PROBLEM 22.11
PROBLEM 22.12
22.5 NUCLEIC ACIDS
TABLE 22.3 Nucleobases, Nucleosides, and Nucleotides
FIGURE 22.37 Nucleoside formation.
TABLE 22.4 Spectroscopic Data for 22.44, 22.45, 22.46
FIGURE 22.38 Double helix of DNA showing major and minor grooves.
Focus on ATP
PROBLEM 22.13
Key Points from Sections 22.4 and 22.5
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23 Catalysis of Organic Reactions
23.1 INTRODUCTION
FIGURE 23.1 Reaction profiles of catalyzed and uncatalyzed reactions.
23.2 CATALYSIS BY ACIDS AND BASES
FIGURE 23.2 Catalysis of ester hydrolysis by acids or bases.
FIGURE 23.3 pH dependendance of the rate of formation of acetone oxime. Note: Mechanism remains the same over pH range of interest but still has an upper limit.
FIGURE 23.4 Mechanism of oxime formation.
FIGURE 23.5 Iodination of acetone.
PROBLEM 23.1
PROBLEM 23.2
Key Points from Sections 23.1 and 23.2
23.3 LEWIS ACID CATALYSIS
23.3.1 REACTIONS OF CARBONYL COMPOUNDS
FIGURE 23.6 Lewis acid-catalyzed reactions of aromatic compounds.
FIGURE 23.7 Coordination of oxygen to a Lewis and a Brønsted acid.
FIGURE 23.8 Lewis acid catalysis of simple carbonyl transformations.
FIGURE 23.9 Mechanism of the Mukaiyama aldol condensation.
FIGURE 23.10 Examples of the Mukaiyama aldol condensation.
FIGURE 23.11 Conjugate additions catalyzed by Lewis acids.
23.3.2 CATALYSIS OF DIELS–ALDER REACTIONS
FIGURE 23.12 Lewis acid-catalyzed Diels–Alder reactions.
PROBLEM 23.3
PROBLEM 23.4
Key Points from Section 23.3
23.4 PHASE-TRANSFER CATALYSIS
FIGURE 23.13 Mechanism of PT catalysis of an SN2 reaction.
FIGURE 23.14 PT catalysis of SN2 substitutions.
FIGURE 23.15 Examples of PT catalysis.
FIGURE 23.16 Permanganate is solubilized in benzene in the presence of 18-C-6.
FIGURE 23.17 Permanganate oxidations in two-phase systems containing crown ethers.
FIGURE 23.18 Use of crown ethers as PT catalysts.
PROBLEM 23.5
PROBLEM 23.6
Key Points from Section 23.4
23.5 REACTIONS CATALYZED BY METAL SURFACES
FIGURE 23.19 Reduction of carbon–carbon multiple bonds using Adams’ catalyst.
FIGURE 23.20 Stereospecific hydrogenation of alkynes to cis-alkenes.
FIGURE 23.21 Hydrogenolysis catalyzed by palladium systems.
FIGURE 23.22 Raney nickel-catalyzed reactions.
23.6 REACTIONS CATALYZED BY TRANSITION METAL COMPLEXES
23.6.1 WACKER OXIDATION AND RELATED REACTIONS
FIGURE 23.23 Stoichiometry of the Wacker oxidation.
FIGURE 23.24 Mechanism of the Wacker oxidation of ethene.
FIGURE 23.25 The Wacker–Tsuji oxidation in synthesis.
FIGURE 23.26 The Wacker–Tsuji oxidation in steroid synthesis.
PROBLEM 23.7
FIGURE 23.27 Mechanism of hydrogenation using Wilkinson’s catalyst. The sections in blue are not on the main catalytic pathway; although they occur at measurable rates, these are at least 1000 times slower than the main pathway.
23.6.2 HOMOGENEOUS HYDROGENATION
FIGURE 23.28 Uses of Wilkinson’s catalyst.
FIGURE 23.29 Applications of Crabtree’s catalyst in synthesis.
TABLE 23.1 Directed Hydrogenation Using the Crabtree Catalyst
FIGURE 23.30 Applications of directed hydrogenation using the Crabtree catalyst.
FIGURE 23.31 BINAP (23.11) ruthenium complexes in asymmetric hydrogenation.
PROBLEM 23.8
23.6.3 COUPLING REACTIONS
FIGURE 23.32 Outline mechanism of palladium(0)-catalyzed coupling reactions.
FIGURE 23.33 Kumada–Corriu coupling.
FIGURE 23.34 Negishi couplings.
FIGURE 23.35 Stille couplings.
FIGURE 23.36 Suzuki couplings.
FIGURE 23.37 Sonogashira couplings.
PROBLEM 23.9
Key Points from Sections 23.5 and 23.6
23.7 Organocatalysis*
FIGURE 23.38 Organocatalysis in action.
PROBLEM 23.10
PROBLEM 23.11
23.8 ENZYME CATALYSIS
FIGURE 23.39 Step 1 of chymotrypsin-catalyzed hydrolysis of peptides.
FIGURE 23.40 Step 2 of chymotrypsin-catalyzed hydrolysis of peptides.
FIGURE 23.41 Step 3 of chymotrypsin-catalyzed hydrolysis of peptides.
FIGURE 23.42 Step 4 of chymotrypsin-catalyzed hydrolysis of peptides.
FIGURE 23.43 Enantioselective enzymatic hydrolysis in synthesis.
FIGURE 23.44 Other synthetic transformations catalyzed by isolated enzymes or microorganisms.
Key Points from Sections 23.7 and 23.8
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24 Organic Chemistry in Industry
24.1 INTRODUCTION
24.2 PROCESS CHEMISTRY VERSUS RESEARCH CHEMISTRY
24.3 PHARMACEUTICAL INDUSTRY
24.3.1 INTRODUCTION
24.3.2 DRUG DISCOVERY
24.3.3 DRUG DEVELOPMENT: PRECLINICAL TESTING
24.3.4 DRUG DEVELOPMENT: CLINICAL TESTING
24.3.5 PERSONALIZED MEDICINE
24.3.6 THE FUTURE: PROBLEMS AND OPPORTUNITIES
24.4 AGROCHEMICALS
24.4.1 HERBICIDES
Focus on the REACH Regulations*
24.4.2 FUNGICIDES
Focus on Potato Blight
FIGURE 24.1 Blighted potato.
FIGURE 24.2 Fungicides used against potato blight.
24.4.3 INSECTICIDES
FIGURE 24.3 Spinosyn structures.
24.5 DYES AND COLORANTS
24.5.1 TEXTILE DYES
FIGURE 24.4 Dyes from natural sources.
FIGURE 24.5 Structures of some of the early aniline dyes.
PROBLEM 24.1
PROBLEM 24.2
FIGURE 24.6 Structures of some typical disperse dyes.
24.5.2 FOOD DYES
FIGURE 24.7 Artificial dyes legally permitted for use in foods and cosmetics in the United States.
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25 Organic Chemistry and the Environment
25.1 INTRODUCTION
25.2 PESTICIDES
FIGURE 25.1 Compounds banned by the Stockholm convention as POPs.
Focus on POPs and VOCs
PROBLEM 25.1
FIGURE 25.2 Organophosphate insecticides.
PROBLEM 25.2
FIGURE 25.3 Carbamates used as insecticides.
PROBLEM 25.3
25.3 ENDOCRINE DISRUPTORS
PROBLEM 25.4
FIGURE 25.4 Phytoestrogens.
25.4 CHLOROFLUOROCARBONS AND THEIR REPLACEMENTS
25.5 POLYCYCLIC AROMATIC HYDROCARBONS
FIGURE 25.5 Toxic PAHs.
25.6 PLASTICS: RECYCLE, DEGRADE, OR BURN?
25.7 IS “GREEN CHEMISTRY” THE FUTURE?
FIGURE 25.6 Green reactions with water as solvent.
PROBLEM 25.5
FIGURE 25.7 Traditional synthesis of ibuprofen.
FIGURE 25.8 Catalyzed reactions in water.
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26 Organic Chemistry in Forensic Science
26.1 INTRODUCTION
26.2 DRUGS OF ABUSE
26.2.1 CATEGORIES OF DRUGS OF ABUSE
PROBLEM 26.1
PROBLEM 26.2
FIGURE 26.1 Amphetamines.
FIGURE 26.2 Syntheses of amphetamines.
PROBLEM 26.3
FIGURE 26.3 Barbiturates.
FIGURE 26.4 Benzodiazepines.
PROBLEM 26.4
26.2.2 PRESUMPTIVE TESTS FOR DRUGS OF ABUSE
FIGURE 26.5 Marquis reaction of amphetamine.
FIGURE 26.6 Mechanism of the reaction of Erlich’s reagent with indoles.
PROBLEM 26.5
26.2.3 INSTRUMENTAL METHODS
FIGURE 26.7 GC and mass spectrum of amphetamine, showing tailing.
FIGURE 26.8 Derivatization of amphetamines.
FIGURE 26.9 Derivatization of morphine.
FIGURE 26.10 GCMS of a mixture of derivatized opiates. Note: Separation of opiates derivatized with N,O-bis(trimethylsilyl)acetamide by GC: (1) codeine, (2) acetyl codeine, (3) morphine, (4) 6-monoacetylmorphine, (5) diamorphine, (6) papaverine, (7) noscapine, and (8) caffeine (C22 is the internal standard).
PROBLEM 26.6
26.2.4 DESIGNER DRUGS
FIGURE 26.11 Designer drugs.
PROBLEM 26.7
Key Points from Section 26.2
26.3 POISONS AND POISONING
FIGURE 26.12 (a) Before and (b) after photos of Victor Yushenko who was poisoned with dioxin.
PROBLEM 26.8
Key Points from Section 26.3
26.4 TESTING FOR BLOOD
FIGURE 26.13 Phenolphthalein in the KM test.
FIGURE 26.14 Oxidation of leucomalachite green.
FIGURE 26.15 Benzidine derivatives used in presumptive blood testing.
FIGURE 26.16 Oxidation of benzidine in the presence of blood.
FIGURE 26.17 Oxidation of luminol.
PROBLEM 26.9
26.5 DYES, INKS, AND PAPER
26.6 TRACE EVIDENCE
FIGURE 26.18 IR spectra of cotton (a) and wool (b).
FIGURE 26.19 IR spectrum of an acrylic fiber. Note the CN triple-bond absorption at 2243 cm−1 and the carbonyl absorption at 1733 cm−1. If you recall the chapter on polymers, pure polyacrylonitrile is very difficult to process, and usable fibers usually contain other acrylic materials, including esters and amides. Like most fibers, this absorbs some moisture from the atmosphere, so an OH as well as an NH peak is also observed.
FIGURE 26.20 Pyrolysis GC.
FIGURE 26.21 Pyrolysis GC of (a) nylon-6 and (b) nylon-6,6.
FIGURE 26.22 Pyrograms of some natural materials.
FIGURE 26.23 IR spectra of three clearcoat resins from car paint.
FIGURE 26.24 Pyrograms of the same three clearcoat resins.
FIGURE 26.25 IR spectrum of polycarbonate.
FIGURE 26.26 IR spectrum of ABS copolymer.
FIGURE 26.27 IR spectrum of PVC.
PROBLEM 26.10
26.7 VISUALIZATION OF FINGERPRINTS
Key Points from Sections 26.4 through 26.7
REVIEW PROBLEMS
Back Matter
Appendix A: Glossary of Abbreviations and Acronyms
Appendix B: Some Common/Trivial Names You Need to Know
Index

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