Chapter 25, Problem 59PP

(a)

Interpretation Introduction

Interpretation:

The products formed in the given set of transformation need to be predicted.

Concept introduction:

$\alpha$-bromination of carboxylic acid in presence of bromine and a catalytic amount of phosphorous tribromide to form $\alpha$-bromocarboxylic acid is known as Hell-Volhard-Zelinsky reaction.  The formed $\alpha$-bromocarboxylic acid when treated with ammonia gives $\alpha$-aminocarboxylic acid as the product.

(b)

Interpretation Introduction

Concept introduction:

Strecker synthesis is a process in which the aldehyde reacts with ammonium chloride and alkali cyanide to form $\alpha$-aminonitrile.  The formed $\alpha$-aminonitrile is undergoes hydrolysis to give the respective amino acids.  The general scheme can be shown as,

Steps involved in Strecker synthesis are,

• Protonation of carbonyl
• Nucleophilic attack of ammonia to form imine
• Attack of cyanide to form $\alpha$-aminonitrile
• Hydrolysis to give $\alpha$-aminoacid

(c)

Interpretation Introduction

Concept introduction:

Amidomalonate synthesis is a process in which a halide is converted to an amino acid with two new carbon atoms (comes from amidomalonate).  By use of this method a new alkyl groups can be introduced.  A general scheme of this synthesis is shown below,

Steps involved in amidomalonater synthesis are,

• Deprotonation of $\alpha$ carbon in amidomalonate
• Alkylation of enolate
• Hydrolysis of ester using aqueous acid
• Decarboxylation at high temperature