Chapter 24, Problem 4PP

Interpretation Introduction

Interpretation:

The Strecker synthesis of DL-phenylalanine is to be outlined, and by preparing the starting aldehyde using acrolein and methanethiol, Strecker synthesis of DL-methanethiol is to be outlined.

Concept introduction:

舧 Amino acids are organic compounds containing amine ($-{\text{NH}}_2$) and carboxyl ($-\text{COOH}$) functional group along with a side chain (R group) specific to each amino acid.

舧 Strecker synthesis involves treating an aldehyde with ammonia and hydrogen cyanide to give an aminonitrile, which can be hydrolyzed to an αa-amino acid.

The general reaction is as:

舧 The Strecker synthesis involves formation of imine from phenyl acetaldehyde and ammonia, which on addition of hydrogen cyanide produces $\alpha -$ amino nitrile, and further undergoes hydrolysis to yield DL-phenylalanine.

舧 Acrolein and methanethiol on treating with a base gives $3-\left(\text{methylthio}\right)\text{propanal}$, which when subjected to Strecker synthesis forms imine from $3-\left(\text{methylthio}\right)\text{propanal}$ and ammonia, which on addition of hydrogen cyanide produces $\alpha -$ amino nitrile, and further undergoes hydrolysis in the second step to yield DL-Methionine.