Page 80 - Practical-organic-3

➢ Characteristic IR absorptions of some functional groups:

-1
Functional group Frequency (cm ) Band intensity
3
▪ sp hybridized, Alkane 2850-3000 M (sh)
2
▪ sp hybridized, Alkene 3000-3250 M (sh)
▪ sp hybridized, Alkyne 3300 M-S (sh)

▪ Aldehyde 2750 & 2850 M (sh)

,
▪ Primary amine, Amide 3300-3500 M (br, 2 spikes)

,
▪ Secondary amine, Amide 3300-3500 M (br, 1 spike)

▪ Tertiary amine, Amide RN(R3), RCONR2 None

▪ Alcohols 3400-3650 S (sh)
▪ Phenols 3200-3600 S (br)
(hydrogen bonded)

▪ Carboxylic acids 2400-3500 S (br)

▪ Nitriles 2210-2280 S (sh)

▪ Acetylenes 2100-2260 W (sh)

▪ Anhydrides 1750 & 1820 S, S (sh)

▪ Esters 1735-1750 S (sh)

▪ Aldehydes 1720-1740 S (sh)

▪ Ketones 1710-1730 S (sh)

▪ Carboxylates 1700-1725 S (br)

▪ Amide 1690 S (sh)

▪ Olefins 1640-1680 W (sh)

1500-1550
▪ Nitro groups (Asymmetric stretch) S, S (sh)

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