N
X
C
O
N
S
Hal
Solvents
Natural
Products
P Si
C
C
C C
C
C
326
7 IR
Assignment
Range
Comments
C–O st
1260–970
Strong, often doublet
Subranges:
1075–1000
CH 2 –OH
1125–1000
CH–OH
1210–1100
C–OH
1275–1150
ar C–OH
In the same range: 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
O–H δ oop
<700
Medium, of no practical significance
Examples (v ~ in cm -1 )
OH
3250
1430
1075
1050
OH
3335
1350
O H
3290
1430
1020
O H
3215
1368
1220
OH
OH
3450
1370
1260
1195
O H
3460
1315
1237
1210
7.8.2 Ethers, Acetals, and Ketals
In acetals and ketals, the C–O stretching vibrations are split into 3, sometimes
even 4 to 5 bands.
Acetals have an additional band due to a special C–H δ vibration.
The C–H st vibration frequency is especially low for OCH 3 st (2850–2815) and
OCH 2 st (2880–2835).
%T
400
800
1200
1600
2000
2800
3600
C–O–C st sy
C–O–C st as
X
C
O
N
S
Hal
Solvents
Natural
Products
P Si
C
C
C C
C
C
326
7 IR
Assignment
Range
Comments
C–O st
1260–970
Strong, often doublet
Subranges:
1075–1000
CH 2 –OH
1125–1000
CH–OH
1210–1100
C–OH
1275–1150
ar C–OH
In the same range: 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
O–H δ oop
<700
Medium, of no practical significance
Examples (v ~ in cm -1 )
OH
3250
1430
1075
1050
OH
3335
1350
O H
3290
1430
1020
O H
3215
1368
1220
OH
OH
3450
1370
1260
1195
O H
3460
1315
1237
1210
7.8.2 Ethers, Acetals, and Ketals
In acetals and ketals, the C–O stretching vibrations are split into 3, sometimes
even 4 to 5 bands.
Acetals have an additional band due to a special C–H δ vibration.
The C–H st vibration frequency is especially low for OCH 3 st (2850–2815) and
OCH 2 st (2880–2835).
%T
400
800
1200
1600
2000
2800
3600
C–O–C st sy
C–O–C st as