Courses for Kids
Free study material
Offline Centres
Store Icon

How will you convert benzaldehyde into following compounds? More than one step be required.
(i) Benzophenone
(ii) Benzoic acid

Last updated date: 14th Jun 2024
Total views: 402k
Views today: 8.02k
402k+ views
Hint: Benzaldehyde is a compound having an aldehyde group attached to benzene. Benzophenone is a compound having two benzene groups connected with a carbonyl group. While benzoic acid is a compound having carboxyl groups attached to benzene. Benzene to benzoic acid is a simple step conversion while the other involves two to three steps.

Complete step by step answer:
(i) When aldehyde is oxidized, a carboxylic acid is obtained. Benzaldehyde is the simplest aromatic aldehyde. It has an almond-like odor. Benzoic acid is a colorless solid. The chemical formula of benzoic acid is ${{\text{C}}_6}{{\text{H}}_5}{\text{COOH}}$.
Thus benzaldehyde is converted to benzophenone in three steps:
Oxidation of benzaldehyde to benzoic acid.
Benzaldehyde is oxidized to benzoic acid in the presence of alkaline potassium permanganate. Since benzaldehyde possesses a benzene ring, it facilitates the electrophilic substitution reaction. The chemical equation for oxidation of benzaldehyde to benzoic acid is given below:
Benzaldehyde Benzoic acid
Conversion of benzoic acid to benzene.
Benzoic acid is heated with soda lime which is a mixture of ${\text{NaOH}}$ and ${\text{CaO}}$, benzene is obtained. The reaction is given below:
Conversion of benzene to benzophenone.
Benzene is reacted with benzoyl chloride, ${{\text{C}}_6}{{\text{H}}_5}{\text{COCl}}$ in the presence of ${\text{Al}}{{\text{Cl}}_3}$, benzophenone, ${{\text{C}}_6}{{\text{H}}_5}{\text{CO}}{{\text{C}}_6}{{\text{H}}_5}$ is obtained. The chemical equation is given below:
${{\text{C}}_6}{{\text{H}}_6} + {{\text{C}}_6}{{\text{H}}_5}{\text{COCl}}\xrightarrow{{{\text{Al}}{{\text{Cl}}_3}}}{{\text{C}}_6}{{\text{H}}_5}{\text{CO}}{{\text{C}}_6}{{\text{H}}_5}$
This reaction is called Friedel Crafts acylation.

Benzaldehyde can also be converted to benzoic acid by Cannizaro reaction. Cannizaro reaction is a type of disproportionation reaction. This involves disproportionation of an aldehyde which lacks $\alpha - $ hydrogen atom to salt of an acid and a primary alcohol. The reaction is given below:
seo images
$ + {\text{NaOH}} \to $
seo images
$ + $
seo images
$\xrightarrow{{{{\text{H}}^ + }}}$
seo images

Benzaldehyde Benzyl alcohol Sodium benzoate