PROBLEM 25.65 - Organic Chemistry

Question

Question: Devise a synthesis of each compound from benzene. You may use any other organic or inorganic reagents.

a.

b.

c.

d.

e.

f.

Step-by-Step Solution

Answer

Answer 

a.

b.

c.

d.

e.

f.

Reactions of benzene

Nitrobenzene is generated as the product when benzene is subjected to a reaction with   and HNO₃ and H₂SO₄ . The combination of benzene with CH₃Cl  and AlCl₃  gives rise to methylbenzene.

Synthesis of compounds from benzene

Various benzene derivatives can be prepared by using electrophilic aromatic substitution. Some of the electrophilic aromatic substitution reactions include nitration and Friedel Crafts alkylation.  

Synthesis of various compounds from benzene

a. To obtain compound a, benzene undergoes nitration to form nitrobenzene. Nitrobenzene undergoes bromination in the presence of Lewis acid to form 1-bromo-3-nitrobenzene. The nitro group gets reduced to form 3-bromoaniline. The amino group undergoes acetylation with acetic anhydride to form N-(3-bromophenyl) acetamide. The reactions can be given as:

Synthesis of compound a from benzene

b.The first step is the Friedel Crafts alkylation of benzene to form toluene. Toulene gets subjected to nitration to form 1-methyl-4-nitrobenzene. The nitro group gets reduced to form p-toluidene. This reacts with sodium nitrite, hydrochloric acid, and water to form 1-iodo-4-methylbenzene. The reaction can be given as:

Synthesis of compound b from benzene

 

c. Benzene gets subjected to nitration to form nitrobenzene. Nitrobenzene gets reduced to form aniline. Aniline reacts with sodium nitrite, hydrochloric acid, and CuCN to form cyanobenzene. This molecule undergoes bromination to form 3-bromobenzonitrile. The reaction can be given as:

Synthesis of compound c from benzene

d. Benzene gets subjected to bromination to form bromobenzene. This molecule undergoes nitration to form ortho and para products. This synthesis requires the ortho product, 1-bromo-2-nitrobenzene. The nitro group gets reduced to form 2-bromoaniline. This molecule reacts with sodium nitrite, hydrochloric acid, and water to form 2-bromophenol. The reaction can be given as:

Synthesis of compound d from benzene

e. Benzene undergoes alkylation to form methylbenzene. This molecule gets subjected to nitration to form 1-methyl-4-nitrobenzene. This molecule reacts with potassium permanganate and converts the methyl group of the previous molecule to COOH. It then reacts with sodium nitrite, hydrochloric acid, and water to form the compound e. The reaction can be given as: 

Synthesis of compound e from benzene

f. Benzene undergoes nitration to form nitrobenzene. This molecule gets reduced to form aniline. Aniline reacts with sodium nitrite, hydrochloric acid, and water to form phenol. Phenol combines with C₆₃H₅N₂⁺Cl^-  to form compound f. The reaction can be given as: 

Synthesis of compound f from benzene