In each of the sets that follow, match the proper compound with the appropriate

Question

In each of the sets that follow, match the proper compound with the appropriate set of IR bands and give the rationale for your assignment.
a) dodecane, 1-decene, 1-hexyne, 1,2-dimethylbenzene
i. 3311(s), 2961(s), 2119(m) cm-1 __________________
ii. 3020(s), 2940(s), 1606(s), 1495(s), 741(s) cm-1 ___________________
iii. 3049(w), 2951(m), 1642(m) cm-1 _________________
iv. 2924(s), 1467(m) cm-1 ________________

b) phenol, benzyl alcohol, methoxybenzene
i. 3060(m), 2835(m), 1498(s), 1247(s), 1040(s) cm-1 _________________
ii. 3370(s), 3045(s), 1595(s), 1224(s), 741(s) cm-1 ___________________
iii. 3030(broad s), 3030(m), 2950(m), 1454(m), 1223(s) cm-1 _________________

c) 2-pentanone, acetophenone, 2-phenylpropanal, heptanoic acid, 2-methylpropanamide, phenyl acetate, 1-aminoctane
i. 2070(m), 2978(m), (2825(s), 2720(m), 1724(s) cm-1 _____________
ii. 3372(m), 3290(m), 2925(s) cm-1 _____________
iii. 3070(w), 1765(s), 1215(s), 1193(s) cm-1 ________________
iv. 3300-2500(br, s), 2950(m),1711(s) cm-1 __________________
v. 3060(m), 3170(s), 2960(m), 1640(s) cm-1 _________________
vi. 2964(s), 1717(s) cm-1 _______________________

Explanation / Answer

a) dodecane, 1-decene, 1-hexyne, 1,2-dimethylbenzene

i. 3311(s), 2961(s), 2119(m) cm-1 __1-Hexyne___due to characteristic =C–H stretching frequency around 3300 cm-1.and due to C=C stretching in 2260–2100 -1 cm-1 region.

ii. 3020(s), 2940(s), 1606(s), 1495(s), 741(s) cm-1 ___1-Decene__ due to characteristic =C-H and C=C frequencies in 3020(s), 2940(s) and 1606(s) cm-1 regions. =C-H strong bending frequency around 675-1000 cm-1 region.

iii. 3049(w), 2951(m), 1642(m) cm-1 __1,2-Dimethylbenzene. A simplistic spectrum around 3000-3100 cm-1 region and characteristic C=C stretching frequency around 1600(s) cm-1 region.

iv. 2924(s), 1467(m) cm-1 ____Dodecane__ C-H stretching frequency around 3000 cm-1 and      -C-H bending frequency around 1350-1480 cm-1 region.

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b) phenol, benzyl alcohol, methoxybenzene

i. 3060(m), 2835(m), 1498(s), 1247(s), 1040(s) cm-1 ___ methoxybenzene ____

ii. 3370(s), 3045(s), 1595(s), 1224(s), 741(s) cm-1 ____ benzyl alcohol ___. characteristic      C–OH strong and broad stretching frequency around 3200-3600 cm-1. C-O strong stretching frequency around 1050-1250 cm-1 region. C-H strong bending frequency around 675-1000 cm-1 region.

iii. 3030(broad s), 3030(m), 2950(m), 1454(m), 1223(s) cm-1 ____ phenol ___ characteristic      C–OH strong and broad stretching frequency around 3200-3600 cm-1 region.

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c) 2-pentanone, acetophenone, 2-phenylpropanal, heptanoic acid, 2-methylpropanamide,

phenyl acetate, 1-aminoctane

i. 2070(m), 2978(m), (2825(s), 2720(m), 1724(s) cm-1 __2-phenylpropanal __ characteristic C=O stretch frequency around 1720-1740 cm-1 region. Characteristic =C-H stretch frequency around 2820-2850 & 2720-2750 cm-1regions. _

ii. 3372(m), 3290(m), 2925(s) cm-1 ___1-aminoctane ____ characteristic two bands for N-H stretch of primary amines around 3300-3500 cm-1 region.

iii. 3070(w), 1765(s), 1215(s), 1193(s) cm-1 __ phenyl acetate ___ characteristic C=O stretch frequency around 1750 cm-1 region.

iv. 3300-2500(br, s), 2950(m),1711(s) cm-1 ___ heptanoic acid ___ characteristic      C–OH strong and broad stretching frequency around 3300-3500 cm-1. characteristic C=O stretch frequency around 1700-1725 region.

v. 3060(m), 3170(s), 2960(m), 1640(s) cm-1 __2-methylpropanamide ____ characteristic C=O stretch frequency around 1640-1690 cm-1 region.

vi. 2964(s), 1717(s) cm-1 ____2-pentanone ____ characteristic C=O stretch frequency around 1710-1720 cm-1 region.

Data for acetophenone is missing.

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