Question

Benzyl ethyl ether reacts with concentrated aqueous HI to form two initial organic products (A and B). Further reaction of product B with HI produces organic product C. Draw the structures of these three products.

Answer 1

When an ether is treated with an acid, an alkyl halide and an alcohol are produced. When the alcohol is further treated with HI, another alkyl halide is obtained Con. HI + HO (ethoxymethyl)benzene Con. HI

Answer 2

Concepts and reason

Nucleophilic substitution reaction: nucleophilic substitution reaction is a reaction where the nucleophile attacks on the alkyl halide and replaces halogen atom during the reaction. Nucleophile substitution reactions are two types:

1.Uni-molecular nucleophilic reaction ${{\rm{S}}_{\rm{N}}}{\rm{1}}\,{\rm{reaction}}$

2.Bi-molecular nucleophilic reaction ${{\rm{S}}_{\rm{N}}}{\rm{2}}\,{\rm{reaction}}$

Fundamentals

1.Uni-molecular nucleophilic reaction ${{\rm{S}}_{\rm{N}}}{\rm{1}}\,{\rm{reaction}}$ :

In this reaction, rate of the reaction depends only on substrate concentration, and carbocation is the intermediate in this reaction.

2.Bi-molecular nucleophilic reaction ${{\rm{S}}_{\rm{N}}}{\rm{2}}\,{\rm{reaction}}$ :

In this reaction, rate of the reaction depends on both substrate and reagent concentrations, and transition state is the intermediate in this reaction.

Ether reactivity with HI:

Ethers react with HI either in ${{\rm{S}}_{\rm{N}}}{\rm{1}}\,\,{\rm{or}}\,{{\rm{S}}_{\rm{N}}}{\rm{2}}$ pathway; reaction mechanism of this reaction completely depends on the structure of the ether.

a.If the leaving group leaves first to form stable carbocation, this reaction follows ${{\rm{S}}_{\rm{N}}}{\rm{1}}\,{\rm{pathway}}$ .

b.If the leaving group leaves after associating with the nucleophile, this reaction follows ${{\rm{S}}_{\rm{N}}}{\rm{2}}\,{\rm{pathway}}$ .

The given reaction condition is drawn below.

‎The given substrate is ether and it is following ${{\rm{S}}_{\rm{N}}}{\rm{1}}\,{\rm{reaction}}\,{\rm{pathway}}$ .

The given reaction is drawn below with products during ${{\rm{S}}_{\rm{N}}}{\rm{1}}\,{\rm{reaction}}$ .

The above reaction follows ${{\rm{S}}_{\rm{N}}}{\rm{1}}\,{\rm{reaction}}\,{\rm{pathway}}$ , since ether gives the stable intermediate by leaving ethoxide ion.

Ans:

The three products of the reaction are,