FAQs on Cannizzaro reaction in JEE

Cannizzaro reaction is one of the most important reactions in organic chemistry, included in JEE syllabus. It is a general reaction of aldehydes lacking -hydrogen atom. Some FAQs related to Cannizzaro reaction are:

Question: What is Cannizzaro reaction?

Answer: When aldehydes lacking -hydrogen atoms are heated in the presence of a concentrated alkali, they undergo self-oxidation and reduction (disproportionation) reaction to form one molecule each of alcohol and carboxylic acid salt. This reaction is named after its discoverer Stanislao Cannizzaro and is known as Cannizzaro reaction.

\(2HCHO + Conc.\;\; KOH  \underrightarrow{\Delta} CH_3OH + HCOOK\)

Questions: What is the general mechanism of Cannizzaro reaction?

Answer: Cannizzaro reaction follows a third order kinetics, it is second order in aldehyde and first order in the base. The general mechanism of this reaction is discussed below:

  • The hydroxide ion attacks on the carbonyl carbon leading to deprotonation which finally produces a dianion.
  • The dianion produced is an unstable intermediate which releases a hydride anion.
  • The generated hydride ion attacks another molecule of aldehyde.
  • The dianion converts itself into a carboxylate anion and the aldehyde to an alkoxide.
  • Finally, the alkoxide ion formed in the process picks up a proton from water to form alcohol while the carboxylate ion gets converted to carboxylic acid product.

Questions: Which reference books can one follow for Cannizzaro reaction?

Answer: A brisk walk through reactions of aldehydes from NCERT Chemistry Textbook for class 12th (Part II) will give you a sound idea of this reaction. Apart from this you can follow a reference book to understand the detailed mechanism of this reaction. Some authentic books for understanding the detailed mechanism of Cannizzaro reaction include books from authors like Solomons & Fryhle, Morrison & Boyd. Once you have developed concepts on this topic, you can practice questions from the books of authors like M. S. Chauhan, etc.

For further details related to aldehydes and ketones for JEE chemistry, get in touch with our mentors here at BYJU’s.

Practise This Question

State True or False.

(25)2 = (25)2