Question

Benzaldehyde is converted to benzyl alcohol by

• A. Wurtz reaction
• B. Cannizaro reaction
• C. Fittig reaction
• D. Wurtz-Fittig reaction

Answer 1

Answer: (B)

Key Idea: Write every reaction to find which of them is used to convert benzaldehyde to benzyl alcohol. (i) Wurtz reaction: In this reaction two molecules of alkyl halide react with sodium in presence of ether to form alkane having double the carbon atoms as present in alkyl halide. $\underset{\begin{array}{c}\text{alkyl}\\ \text{halide}\end{array}}{R-}\underset{\begin{array}{c}\text{alkyl}\\ \text{halide}\end{array}}{-R}\stackrel{Ether}{\to }$ $\underset{\text{alkane}}{R-R}+2NaX$ (ii) Fittig reaction: In this reaction two molecules of aryl halide react with sodium to form aromatic hydrocarbon.
(iii) Wurtz-Fittig reaction: In this reaction one molecule of aryl halide and one molecule of alkyl halide react with sodium to form alkyl substituted benzene.
(iv) Cannizaro reaction: This reaction is given by aldehydes which do not have $\alpha -$ hydrogen atoms. This is disproportionation reaction in which half of the molecules are oxidised and other half are reduced.
$\therefore$ Cannizaro reaction is used for conversion of benzaldehyde into benzyl alcohol.