Question

Azoxybenzene can be obtained by the treatment of nitro-benzene with:

• A. $O_2$
• B. $H_2/Pt$
• C. ${Na}_3{AsO}_3/NaOH$
• D. $Zn/NaOH$

Answer 1

Answer: (C)

${Na}_3{AsO}_3/NaOH$

Aromatic compounds are reduced to azoxy compounds by using $N{a}_{3}As{O}_3$ or glucose or $NaOH$. Nitrobenzene first reduces to nitrosobenzene and N-hydroxyaniline. Some of the nitrosobenzene can be further reduced to aniline and N-phenylhydroxylamine, both of which are nucleophiles and can react with the nitroso $N=O$ bond (analogous to a carbonyl). Elimination of water in both reactions produces azobenzene and azoxybenzene respectively.