Chapter 20, Problem 9PP

Interpretation Introduction

Interpretation:

The reactions of amines are to be reviewed with proper examples.

Concept Introduction:

Amines are the organic compounds that contain an amino group $(-{\text{NH}}_2)$.

They can act as nucleophiles and electrophiles in organic reactions.

Amines can be classified into three categories: primary amines, secondary amines, and tertiary amines.

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.

Free radical is an atom, molecule or ion that has unpaired electrons which makes it highly chemically reactive.

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.

Elimination reaction: A reaction in which two substituent groups are detached and a double bond is formed is called elimination reaction.

Addition reaction: It is the reaction in which unsaturated bonds are converted to saturated molecules by the addition of molecules.

The electrophilic aromatic substitution reaction is the reaction between benzene and chlorine, or bromine, in the presence of a catalyst.

Electrophilic substitution reaction is the type of reaction in which an electrophile displaces hydrogen from the compound.

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:

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

Aniline is ortho and para directing in electrophilic substitution reaction. Aniline is an activating group which contributes to electron density at ortho and para positions.