Q. The correct sequence of steps involved in the mechanism of Cannizzaro’s reaction is
A) Nucleophilic attack, transfer of $H^{-}$and transfer of $H^{+}$
B) Transfer of $H^{-}\$, transfer of $H^{+}$ and nucleophilic attack
C) Transfer if $H^{+}$, nucleophilic attack and transfer of $H^{-}$
D) Electrophilic attack by $OH^{-}$, transfer of $H^{+}$ and transfer of $H^{-}$
Explanation
(a)
The Cannizzaro reaction is as
$HCHO + HCHO\overset{KOH(conc.)}{\rightarrow}{CH}_{3}OH\ \ \ \ \ \ \ \ \ + {HCOOK}^{+}$
methyl alcohol acetic acid
The mechanism of Cannizzaro reaction is as
Step I Attack of nucleophile $OH^{-}$ to the carbonyl carbon
[image:12_image283.emf]
Step II The transfer of hydride ion from anion (I) to second molecule of aldehyde and finally rapid transfer of proton takes place.
[image:12_image284.emf]
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.