Chapter 6, Problem 44P

Interpretation Introduction

Interpretation:

The reactions of the Walden cycle likely to take place with the overall inversion of configuration and those likely to occur with the overall retention of the configuration are to be determined. The configurations of the other compounds in the Walden cycle are to be determined. The Walden cycle, based on the use of thionyl chloride instead of ${\text{PCl}}_5$, is to be written.

Concept introduction:

Reaction sequences involve the conversion of one functional group to another, which may also require the addition or loss of carbon from the reactant.

These sequences involve a number of steps carried out by different reagents. Sometimes, different reagents give the same products.

Electrophiles are electron-deficient species, which has positive or partially positive charge. Lewis acids are electrophiles, which accept electron pair.

Nucleophiles are electron-rich species, which has negative or partially negative charge. Lewis bases are nucleophiles, which donate electron pair.

Substitution reaction: A reaction in which one of the hydrogen atoms of a hydrocarbon or a functional group is substituted by any other functional group is called substitution reaction.

Nucleophilic substitution reaction is a reaction in which an electron-rich nucleophile attacks the positive or partial positive charge of an atom or a group of atoms to replace a leaving group.

An ${\text{S}}_{\text{N}}\text{2}$ reaction is the nucleophilic substitution reaction in which two components are involved in the rate determining step. ${\text{S}}_{\text{N}}\text{2}$ reaction occurs in one step.

An ${\text{S}}_{\text{N}}1$ reaction is the nucleophilic substitution reaction in which one component is involved in the rate determining step. ${\text{S}}_{\text{N}}1$ reaction occurs in two step.

The involvement of nearby nucleophile substituent to the reaction center in the substitution process is known as neighboring group participation.

Such participation results in an increase of rate of reaction. The phenomenon is described as Anchimeric assistance.

In this participation, two ${\text{S}}_{\text{N}}\text{2}$ reactions are occurred, which results in two inversion of configuration, that is, overall retention of configuration.

When the order of progression from the group of highest priority to that of the next highest priority is clockwise, it is said to be the $\left(R\right)$ configuration

When the order of progression from the group of highest priority to that of the next highest priority is anticlockwise, then it is said to be the $\left(S\right)$ configuration.