N
X
C
O
N
S
Hal
Solvents
Natural
Products
P Si
C
C
C C
C
C
370
7 IR
370
7 IR
7.13 Amino Acids
Typical Ranges (v ~ in cm -1 )
Assignment
Range
Comments
N–H st
O–H st
3400–2000
Generally strong, broad, very structured
Subranges:
3100–2000
Zwitterions, distinct side band at 2200–2000
3350–2000
Hydrochlorides
3400–3200
Na + salts
NH 3
+ δ as
1660–1590
Weak, for hydrochlorides near the lower limit
NH 3
+ δ sy
1550–1480
Medium
COO – st as
1610–1595
Strong
Subranges:
≈1595
Zwitterions
75%
Na + salts
COOH
1755–1700
Hydrochlorides; in α-amino acids: 1760–1730
%T
400
800
1200
1600
2000
2800
3600
NH 3
+ δ
rocking
C=O st
NH 3
+
sy
δ
NH 3
+
st
and comb
X
C
O
N
S
Hal
Solvents
Natural
Products
P Si
C
C
C C
C
C
370
7 IR
370
7 IR
7.13 Amino Acids
Typical Ranges (v ~ in cm -1 )
Assignment
Range
Comments
N–H st
O–H st
3400–2000
Generally strong, broad, very structured
Subranges:
3100–2000
Zwitterions, distinct side band at 2200–2000
3350–2000
Hydrochlorides
3400–3200
Na + salts
NH 3
+ δ as
1660–1590
Weak, for hydrochlorides near the lower limit
NH 3
+ δ sy
1550–1480
Medium
COO – st as
1610–1595
Strong
Subranges:
≈1595
Zwitterions
75%
Na + salts
COOH
1755–1700
Hydrochlorides; in α-amino acids: 1760–1730
%T
400
800
1200
1600
2000
2800
3600
NH 3
+ δ
rocking
C=O st
NH 3
+
sy
δ
NH 3
+
st
and comb