Chapter 11.SE, Problem 59AP

Interpretation Introduction

Interpretation:

The reason has to be explained for formation nitrile product with S stereochemistry when the reaction of S tosylate with cyanide ion.

Concept introduction:

S_N2 reaction:

The alcohol is reaction with acids like hydrochloric acid or hydrobromic acid, the bromine atom attacks back side of the carbon atoms in simultaneous manner and which is bearing alcohol group which yield the corresponding product.

Example:

Alcohol is reaction with tosyl chloride in pyridine which provides retention of configuration of tosylated compound. This tosylated compound is further reaction with sodium methoxide which undergoes again S_N2 type of reaction, the methoxide ion attacks the carbon atom through the back side and provides Inverse configuration of methoxy compound. This is shown below,

R and S nomenclature:

It is used to assign the molecule using CIP rules.

The CIP rules are as follows:

Select the chiral carbon and assign the numbers according to the decreasing atomic mass of atoms attached to it.

If the numbering follows clockwise direction then the molecule is termed as R and if it follows anti-clockwise direction then molecule is termed as S.

Given information:

The given compound is shown below,