N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
355
7.11 Carbonyl Compounds
355
Typical Ranges (v ~ in cm -1 )
Assignment
Range
Comments
C=O st
1790–1650
Strong. In Raman, weak to medium
Subranges:
1750–1735
Aliphatic esters
Conjugated
esters:
1730–1710
1730–1715
α,β-Unsaturated esters
Aromatic esters
1690–1670
With intramolecular H bonds
1790–1740
α-Halogenated esters
≈1760
Vinyl esters, C=C st: 1690–1650, strong
≈1760
Phenol esters
≈1735
Phenol esters of aromatic acids
Diesters:
As the corresponding monoesters
Keto esters:
1755–1725
α-Keto esters, generally one band
≈1750 (ketone)
≈1735 (ester)
β-Keto esters, keto form
≈1650
β-Keto esters, enol form,
C=C st: ≈1630, strong
≈1740, ≈1715
γ-Keto esters, pseudoesters: ≈1770
Lactones:
O
O
≈1840
O
O ≈1770
O
O ≈1800
O
O
≈1750 (additional band at
≈1780 if α position is not
substituted)
O
O
≈1735
O
O
≈1760
O
O
≈1720
O
O
≈1730
(often
doublet)
C–O st
1330–1050
2 bands:
st as, very strong, at higher wavenumbers;
st sy, strong, at lower wavenumbers
C–O st as:
Subranges:
≈1185
Formates, propionates, higher aliphatic esters
≈1240
Acetates
≈1210
Vinyl esters, phenol esters
≈1180
γ-Lactones, δ-lactones
≈1165
Methyl esters of aliphatic carboxylic acids
In the same range: Strong bands for C–F st, C–N st, N–O st,
P–O st, C=S st, S=O st, P=O st, Si–O st,
Si–H δ