Answers to Problems. Chapter 2 2. (J' ~ 5. (a) n ~ Chapter 3. n* > n ~ n* n* < n ~ n* < n ~ (J'* > n ~ er* > n ~

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1 Answers to Problems Chapter 1 3. Gamma rays > X-rays > UV > Visible > IR > Radio waves 6. (a) (i) 4 cm- 1 (ii) cm- 1 (iii) cm- 1 (b) x 1 8 MHz to x 1 8 MHz 7. (a) 7.15 kcal/mole (b) x 1 15 cps to.7495 x 1 15 cps 8. (a) kcals mole-1 or kilo Joule mole-1 (b) 4 cm- 1 to cm- 1 (c) x 1 13 cps (Hz) or xl 7 MHz Chapter 2 2. (J' ~ 5. (a) n ~ er* > n ~ (J'* > n ~ n* > n ~ n* n* < n ~ n* < n ~ er* 8. A, 1,4-Pentadiene; B, cis-1,3-pentadiene and C, trans-1,3-pentadiene 9. (i) 249 nm (ii) 342 nm (iii) 226 nm (iv) 418 nm (v) 28 nm (vi) 239 nm 12. (i) 254 nm (ii) 269 nm (iii) 285 nm 15. a < d < b < c 17. (a) 259nm 19. (d) (b) 315 nm (c) 254 nm 2. A is 1,3-cyclohexadiene and B is 1,4-cyclohexadiene. 21. (b) nm and 257 nm 24. (a) 2-propanol, ethanol, heptene, water and dioxane 26. Structure (a) is correct. 28. p-benzoquinone 29. (i) n-n* (ii) n-n* 3. (i) 229 nm (ii) 323 nm Chapter 3 (iii) 351 nm (iv) 281 nm I. (b) Rotational < Vibrational < Electronic 4. (i) 9 (ii) 21 (iii) 7 (iv) 12 (v) 1 5. (i) Esters (ii) Acid halides

2 Answers to Problems (iii) Amides (iv) Anhydrides 9. (a) p-aminoacetophenone < acetophenone < p-nitroacetophenone (b) cyclohexanone < cyclopentanone < cyclobutanone 12. (A) CH3COCH3 (B) CH2=CH-CH2H 14. (b) > (a) 15. (i) b < a < c (ii) (b) < (c) < (a) 16. CH3CH2CONH2 19. trichloroacetic acid < chloroacetic acid < acetic acid < ethanol 2. (i) 33 cm- 1 (Ya-H hydrogen bonded) (ii) 35 cm- 1 (Yc-H aromatic ring) (iii) 299 cm- 1 (Yc-H methyl group) (iv) 17 cm- 1 (Yc=O hydrogen-bonded ester) (v) 154 and 159 cm- 1 (Yc-a. aromatic ring) 21. C 6H 5CH2H 22. CH3COCH3 24. C 6H 5CHO < CH3COCH3 < CH3CHO < CH 3COCJ 26. (i) Inactive (ii) Active (iii) Inactive (iv) Active (v) Inactive (vi) Inactive 28. Butanone 3. m-cresol 31. Benzaldehyde Chapter A The energy of radiation ( kj) is lesser than the dissociation energy of H 2, hence it cannot dissociate. 9. CS 2 has a center of symmetry, whereas N 2 has no center of symmetry and thus the structures must be S-C-S and N-N-, respectively. 1. The compound has trans and planar structure: , 3,11, 454 and 758 cm (a), (b), (c) and (e) will exhibit both the vibrational and rotational Raman spectra; (d) will not exhibit rotational Raman spectrum. 18. H2 > HD > D2. 2. (a), (b) and (d) will exhibit rotational Raman spectra; (c) will not exhibit rotational Roman spectrum. 21. (i) Active (ii) Inactive (iii) Inactive (iv) Active (v) Active 22. The molecule has a trans, planar geometry: f Y-Z-Y I X

3 318 + ORGAN/C SPECTROSCOPY , 733, 743 and 7839 A 24. H3C-C =:C-CH3 Chapter 5 1. For 14N, 2H, 35Cl and 31 P NMR spectroscopy is possible. 3. (a) 2(5 : 3) (b) 3(3 : 2 : I) (c) 3(3 : 2 : 2) 6. (a) 3; one singlet, one triplet and one quartet (b) 3; one singlet, one triplet and one quintet (c) I; singlet ( d) I; singlet 1. Chemical shift positions are and 8 1.5; lax= 1 Hz. 11. (a) ClCHzCC1zCH3 (b) C 6H5-(CH3h (c) C 6H 5 -CH 2CH (CH3)z 12. (a) 1; 3 (3 : 2 : 1) (b) 3 (5 : 2 : 3); 2 (2 : 3) (c) 4 (3 : 2 : 2 : 3); 2 (3 : 2) 14. C 6H 5C(CH3)zCH 2Cl 18. BrCH 2CH 2CH 2Br 21. (i) (ii) (iii) (CH3)zCHOH 25. (a) (CH3)3COH ; 6.51" 27. C 6 H 5CH 2 CH CICH 2CH 2COOH 29. p-nitrophenol 31. C 6H 5CH 2CH 2H Chapter 6 l. (a) 2, (b) 5, (c) 2, (d) l. 4. (a) Two peaks; one singlet and one doublet (b) Three peaks; one singlet, one doublet and one quartet (c) One peak; one triplet (d) Three peaks; one doublet, one triplet and one quartet 5. (a) (CH 3)zCHC =CH (b) (CH 3CH 2)zCHCH 3 (c) CICH 2CHCICCI 3 8. (CH3)zCHCOCH3 9. (a) Six peaks; two singlets, three doublets, and one quartet; the singlet due to 1. (a) ketonic carbon will have the highest and the quartet the lowest 8 value. (b) Four peaks, one singlet, two triplets and one quartet; the singlet will have the highest and the quartet the lowest 8 value. (c) Four peaks; one singlet, one triplet and two quartets; the singlet will have the highest and the quartet the lowest 8 value. (d) Three peaks; one quartet and two triplets; the triplet due to C-3 will have (c) 14. (a) (b) (c) (d) the highest and the quartet the lowest 8 value. (CH3CH 2)JCH (b) CH3CH 2CHOHCH 3 CH 3C ==CCH 2CH 3 5; one singlet, three triplets and one quartet 9; four singlets, four doublets and one quartet 2; one doublet and one triplet 4; one singlet and three triplets

4 Answers to Problems ~ H, Cl Chapter 7 I. (a), (c) 3. (a) 12, (b) 14, (c) 1, (d) 7 5. (a) 3; I : 1 : 1 (b) 5; 1 : 4: 6: 4: I (c) 3; I : 2: I (d) 6; 1 : 5 : 1: 1: 5 : I 6. (a) 7 (b) 8. A, CH(COOH)z; B, CH 2COOH. 9. (a) 35 (b) 8 1. (a) 7; 1 : 6 : 15 : 2 : 15 : 6 :.1 (b) 4; I : 3 : 3 : 1 (c) 7; 1 : 6: 15 : 2: 15 : 6: I (d) 3; 1 : I : I T 13. (c) 14. C 6 H(; 15. Yes; 2 lines in intensity ratio I : /2 Chapter 8 2. (i) HC =C-Br (ii) HCOOCH 3 t C 2H 5 H, CH 3CH=OH, CH 2=H, C2 H ~. 12. CH n-heptane Chapter 9 CH3\ ~ I. CH-CH 2-C-CH3 CH 3d II 2. H 3C-C-CH 2 -CH 2 -COOH 3. H 3 C - ~ - C ( C H 3 h 4. N-C-CH 2-C-O-CH 2CH 3 II HC;;::O, OH and CH 3

5 32. ORGANIC SPECTROSCOPY CHOHCOOH 6. I CHOHCOOH 7. CH 3CH 2C ==CH 8. CH 2 = CH-CH 2H (allyl alcohol or 2-propen-1-ol) CH3CH 2CH 2C ==CH, the isomer may be CH 3CH 2C ==C-CH 3 (other structures are also possible) r CH 2CH 2CCH3 II (CH3hCH-O-CH (CH3h 13. CH 3 -CH-COOH I Br 14. CH 3CH 2CO-O-COCH 2CH (CH3h CHCONH H3C-O-CH 2-C ==N II 17. CH 3CH2CCH3 II 18. (CH 3)3C-OCH3 19. ~ C H, O H 2. CH3COCH 2CH3 11-@ CH3CHzQ-C C-üCH2CH3

6 Index a, ß-unsaturated carboxylic acids, UV, 34 a,ß-unsaturated esters, UV, 34 y-gauche steric compression, 21 Absorption bands, 12: designation of, 13 formation of, 12 Absorption 1aws, 7 Absorption of energy, NMR, 136 Absorption spectra, 5 Acetylenic protons, 147 Acid anhydrides, IR 78 Acid halides, IR 78 Alcohols, IR 69 Aldehydes, IR 72 Aldehydic protons, 148 Alkanes, IR 67 Alkenes, IR 68 Alkyl substituents, 21 Alkynes, IR 69 Allowed transition, 14 Allylic coupling, 167 Amides, IR, 79 Amines and their salts, IR 8 Aminoacidsand their salts, IR, 81 Analysis of NMR spectra, 168 Anisotropie effect, 146 applications of, 92 Aromatic compounds, 4, 41, 42 non-benzenoid, 42 polynuclear, 4 Aromatic coupling, 167 Aromatic hydrocarbons, IR 69 Aromatic protons, 149 Auxochrome, 16 8-Bands, 13 Base peak, 255 Bathochramie shift, 16 Bending vibrations, 56, 57 Benzene and its derivatives, UV 34 Blue shift, 16 13C chemical shifts, 22, 25, 211 a-, ß- and y-effects, 23 13C NMR spectroscopy, 195 applications of, 214 common modes of recording, 196 samp1e handling, 196 theory, 195 use of shift reagents, 214 Carbony1 carbons, 21 Carboxylate axions, IR 75 Carboxylic acid, IR 75 Chemical ionization (Cl) method, 251 Chemical shift, 142, 143, , 146, 152, 17, 199 Chromophore, 15 Combination bands, 61 Comparison between NMR and ESR., 243 Conjugated systems, UV, 17 Continuous wave NMR spectroscopy, 184 Coupled vibrations, 62 Coupling constant (1), 164, 165, 166 Cycloalkanes, IR 68 Daughter ions, 253 Deformations, 56 Deshielding, 142, 148, 149, 15 Detection of isotopes, 256 Deuteration, 178 Deuterium exchange, 178 Deuterium labelling, 178 Dicarbonyl compounds, UV, 32 Difference bands, 61 Double irradiation in ESR, 239 Double irradiation, 177 Double resonance in ESR, 239, 24 Double resonance, 177 DSS as reference, 143

7 322 +Index E-Bands, 13 ELDOR, 24 Electromagnetic radiations, I, 2 Electromagnetic spectrum, 4, 5 Electron impact (EI) method, 25 Electron paramagnetic resonance (EPR), 224 Electron spin resonance (ESR) spectroscopy, 224 instrumentation, 227 interpretation, 237 multiple! structures, 232 theory, 224 Electronic spectroscopy, 7, 15 Electronic transitions, 9 cr ~ n ~ n ~ n ~ cr*, lo cr*, lo n*, 11 n*, 11 Emission spectra, 5 ENDOR, 239 Epoxides, IR, 71 Equivalent and non-equivalent protons, 153 ESR spectra, interpetation of, 237 Esters, IR, 76 Ethers, IR, 71 Exocyclic double bonds, 21 Fermi resonance, 63 Fine structure, 232 Fingerprint region, 92 First order spectra, 169 Flipping of nucleus, 137 Forbidden transition, 14 Fragment ions, 253 Fragmentalion modes, 262 general, 262 of alcohols, 272 of aldehydes and ketones, 276 of alkanes, 265 of alkenes, 267 of alkynes, 268 of amines, 282 of aromatic hydrocarbons, 269 of carboxylic acids, esters and amides, 278 of ethers, acetals and ketals 275 of halogen compounds 27 of heterocychic compounds, 286 of nitriles 283 of nitro compounds, 284 of phenols, 274 of sulphur compounds, 285 of various classes of compounds, 265 Fragmentalion processes, 262 examples of, 262 factors governing, 262 representation of, 262 Frequency, I Fundamental vibrations, nurober of, 58 g factor, 226, 227, 229 Gated decoupling, 198 Geminal coupling, 165 Halogen compounds, IR, 69 Heteroannular dienes, 21 Heteroaromatic compounds, UV, 42, 43 Homoallylic coupling, 167 Homoannular dienes, 2 Hydrogen bonding, IR, 64 Hydrogen bonding, NMR, 151 Hyperchromic effect, 16 Hyperfine structure, 233 Hypsochromic shift, 16 Imides, IR, 79 Index of hydrogen deficiency, 258 Inductive effect, IR, 66 Instrumentation of IR spectroscopy, 52 PMR spectroscopy, 139 Raman, 119 Interpretation of NMR spectra, 168 lonization processes, 25 IR absorption frequencies, table of, 83 IR inactive vibrations, 57, 6 IR spectra, interpretation of, 94 IR spectroscopy, 52, 55, 92 Isotope peak, 256 K-Bands, 13 Ketones, IR, 72 Lactans, IR, 79 Lactones, IR, 76 Long range coupling, 167 Longitudinal relaxation, 139 Magnetic equivalence, 172

8 Index+ 323 Mass spectroscopy (MS), 25 applications, 26 instrumentation, 253 Mass spectrum, 255 Mesomerie effect, IR, 66 Metastahle ions or peaks, 26 Molar absorptivity, 7 Molecular ion peak, confirmation of, 257 Molecular ion, 252 Multiplicity, 159 Multiply charged ions, 259 Nitriles, IR, 83 Nitrites, IR, 82 Nitro compounds, IR, 82 Nitrogen rule, 258 NMR scale, 144 NMR spectra, 168, 17 ana1ysis of, 168 NMR versus ESR, 243 Non-benzenoid aromatic compounds, UV, 42 Nuclear Overhauser effect (NOE), 181 Number of PMR signals, 153 Off-resonance decoupling, 197 Olefinic protons, 148 Overtone bonds, 6 Parent ion, 252 Peak area and proton counting, 156 Phenols, IR, 69 Phosphorus compounds, IR, 83 Photon, energy for, 2 Polarization of Raman lines, 118 Poly-ynes, UV, 26 Polyenes, UV, 26 Precessional frequency, 13 7 Proton exchange reaction, 17 4 Proton nuclear magnetic resonance (PMR or 1H NMR) spectroscopy, 133 applications of, 181 continuous wave (CW), 184 Fourier transform (FT), 184 instrumentation, 14 sample handling, 14 s1gnals, 153 theory, 133 Proton-noise decoupling, 196 Protons on hetero atoms, 17 4 R-Bands, 13 Raman effect, I 7 theories of, 19 Raman spectra, pure rotational, 115, 116 vibrational, 114 vibration-rotational, 117 Raman spectroscopy, 17, 19, 12 applications, 121 effect, 17,18,19,111,112 instrumentation, 119 origin of, 17 samp1e handling, 121 theories of, 19 Raman tube, 12 Raman versus fluorescence spectra, 124 Raman versus IR spectra, 124, 125 Red shift, 16 Relaxation processes, 139 Resonance effect, IR, 66 Ring residues, 21 Rocking, 57 Rule of mutual exclusion, 118 Sampie handling, ESR, 231 IR, 54 PMR, 141 Raman, 121 UV, 9 Satellite peak, 256 Saturation, NMR, 138 Scissoring, 56 Second order spectra, 17 Shielding, 142, 147, 149, 151 Shift reagents, 179 Solvent effer, UV, 18 Spectroscopy (spectromctry), dcfinition, 1 Spectroscopy, infrared (IR), 52, 92 Spin lattice relaxation, 139 Spin number /, 133 Spin systems, nomenclature of, 17 Spin-spin coupling, 157, 172 Spin-spin coupling, 13 C, 212 Spin-spin decoupling, 177 Spin-spin relaxation, 139 Spin-spin splitting, 157, 158, 173 Stretching vibrations, 56, 58, 6, 61 Sulphur compounds, IR, 83

9 324 +Index Theory of ESR spectroscopy, 224 applications of, 24 Theory (origin) of IR spectroscopy, 55 TMS as reference, 143 Transition probability, 14 Transverse relaxation, I39 Twisting, 57 UV and visible spectroscop.y 7, 8, 9 Van der Waals deshielding,!51 Vicinal coupling, 166 Wagging, 57 Wavelength, I Wavenumber, I Woodward-Fieser rules for a,ß-unsaturated carbonyl compounds, 27 for dienes and trienes, 2 exceptions to, 25 Vibrational frequencies, calculation of, 61 Zero-point energy, 113