Question

Which of the following carbonyl compound can give cannizzaro reaction?

• A. $$HCHO$$
• B. $${\left(C{H}_3\right)}_{3}CCHO$$
• C. $$C{H}_{3}C{H}_{2}CHO$$
• D. (a) and (b) above.

Answer 1

The correct option is D (a) and (b) above.

Cannizaro reaction can be generally represented as,
$\underset{\text{R=alkyl, aryl}(no\alpha -H)}{2RCHO}\stackrel{conc.O{H}^{-}}{\to }\underset{1^0\text{alcohol}}{RC{H}_{2}OH}+\underset{\text{acid}}{RC{O}_{2}H}$
Aldehydes witth no $\alpha -H$ atom undergo Cannizzaro reaction on heating with conc. alkali solution.
Both (a) and (b) do not have $\alpha -H$ atom thus they will undergo Cannizzaro reaction. Hence option (d) is correct.
(a)
$2HCHO\stackrel{conc.O{H}^{-}}{\to }C{H}_{3}OH+HC{O_2}^{-}$
(b)
$2{\left(C{H}_3\right)}_{3}CCHO\stackrel{conc.O{H}^{-}}{\to }{\left(C{H}_3\right)}_{3}CC{H}_{2}OH+{\left(C{H}_3\right)}_{3}CC{O_2}^{-}$

(c) $C{H}_{3}C{H}_{2}CHO$ $\alpha$-hydrogen is present so no Cannizaro reaction.