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Solutions for Amino Acids, Peptides, and Proteins
CH
COOEt
COOEt
N
N CH
COOEt
COOEt
N C
COOEt
COOEt
CH2Ph
CH
COOEt
COOEt
N
H2C COOH
H
H2C
CH2CH(CH3)2
COOH
H2C
CH2CH2COOH
COOH
N
O
O
CH
COOEt
COOEt
Br CH
H
COOH
CH COOH
CH2CH(CH3)2
Br
CH COOH
CH2CH2COOH
Br
H3O+
H3O+
H3N CH
CH2CH2COOH
COOH
C
COOEt
COOEt
N
O
O
CH(CH3)2
H3N CH
CH(CH3)2
COOH
CH COOH
H
H2N
H2N CH
CH2CH(CH3)2
COOH
H3O+
H2N CH
CH2CH2COOH
COOH
CH COOH
CH2Ph
H3N
10 All of these reactions use: first arrow: (1) Br /PBr , followed by H O workup; second arrow: (2) 2 3 2
excess NH3, followed by neutralizing workup.
(c)
(b)
(a)
In part (c), care must be taken to avoid reaction α to the other COOH. In practice, this would be 
accomplished by using less than one-half mole of bromine per mole of the diacid.
salt, not
acid—why?
(c)
2) BrCH2CH2COO–
1) NaOEt
∆
∆
1) NaOEt
2) BrCH2Ph
(b)
∆
2) BrCH(CH3)2
1) NaOEt
(a)
11
abbreviate
(1) (2)
(1) (2)
(1) (2)
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