Question

What amino acid is formed when the aldehyde used in the Strecker synthesis is

a. acetaldehyde? b. 2-methylbutanal? c. 3-methylbutanal?

Short answer

In Strecker synthesis, an aldehyde reacts with ammonia to form an imine. A nucleophilic addition reaction with cyanide ion forms an intermediate, which, when hydrolyzed, forms the amino acid.

Step-by-step solution

Strecker synthesis

In Strecker synthesis, an aldehyde reacts with ammonia to form an imine. A nucleophilic addition reaction with cyanide ion forms an intermediate, which, when hydrolyzed, forms the amino acid.

Formation of respective amino acids

a)

Treatment of acetaldehyde with HCN produces the corresponding $\alpha$-aminonitrile which upon hydrolysis produces alanine. The reaction is as follows:

b)

Treatment of 2-methyl butanal with HCN produces the corresponding -amino nitrile which upon hydrolysis produces isoleucine. The reaction is as follows:

c)

Treatment of 3-methyl butanal with HCN produces the corresponding $\alpha$-aminonitrile which upon hydrolysis produces leucine. The reaction is as follows:

Formation of leucine (c)