Chapter 11, Problem 42P

Interpretation Introduction

Interpretation:

The structures for compounds A–J showing stereochemistry in a given sequence are to be written and the stereochemical relationship between (A and C) and (H and J) are to be determined.

Concept introduction:

Electrophiles are electron deficient species that have positive or partially positive charge. Lewis acids are electrophiles that accept electron pair.

Nucleophiles are electron rich species that have negative or partially negative charge. Lewis bases are nucleophiles that 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.

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

The ${\text{S}}_{\text{N}}\text{2}$mechanism of substitution reaction occurs in secondary alkyl halides with an inversion of configuration.

The ${\text{S}}_{\text{N}}\text{2}$reaction takes place in one step. The nucleophile attacks the alkyl halide from the side opposite to the leaving group, resulting in an inversion of configuration.

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

The nucleophilic substitutions in which a nucleophile replaces a leaving group are known as ${\text{S}}_{\text{N}}1$ reactions.

${\text{S}}_{\text{N}}1$ reactions are unimolecular as the rate of reaction is dependent on the concentration of a single reactant.

The stability of carbocation:

${\text{3}}^{\text{o}}\text{carbocation}\text{>}{\text{2}}^{\text{o}}\text{carbocation}{\text{>1}}^{\text{o}}\text{carbocation}\text{>methyl}\text{carbocation}$

Enantiomers and diastereomers are two types of stereoisomers. Enantiomers share mirror image relationship and diastereomers are those in which stereochemistry differs at any one of the chiral centers.

Reaction of alkene with boron hydride followed by treatment with hydrogen peroxide, results in cis addition of hydrogen and hydroxyl groups around the double bond.

Reaction of alcohol with tosyl or mesyl chloride forms tosylates or mesylates, which retains the stereochemistry as the reaction is ester formation and does not involve the chiral carbon.

Tosylates or mesylates can undergo nucleophilic substitution with halides, hydroxides, and acetylides resulting in formation of products with inversion of configuration as the attack of nucleophile occurs at the back side.

Epichlorohydrin is a compound which contains epoxide and chloro substitution alkyl chain. It is formed when ring closure occurs between the hydroxyl and halogen of adjacent carbon atoms.