Question

Draw the most stable product formed in each of the following reactions

Answer 1

Concepts and reason

A condensation reaction is a type of chemical reaction, which has a huge importance in organic synthesis

Aldol condensation:

An aldol condensation reaction is a type of condensation reaction in which two aldehydes have a α-hydrogen atom each, reacting with one another to form a product called aldol.

Claisen Condensation:

Claisen condensation is similar to aldol condensation. An ester which has alpha hydrogen atoms undergoes condensation reaction.

Fundamentals

Claisen Condensation:

Most commonly, the base used in the claisen condensation reaction is alkoxide, ${\rm{R}}{{\rm{O}}^{\rm{ - }}}{\rm{N}}{{\rm{a}}^{\rm{ + }}}$ . The ester, on reaction with the base, forms an ester enolate which again reacts with another molecule of ester.

Enolate is a good nucleophile and ester carbonyl carbon is electrophilic in nature.

The final product of this reaction is a beta-ketoester.

The overall scheme of claisen condensation is as follows:

Aldol condensation:

The mechanism of an aldol condensation contains two steps. The first part is an aldol reaction; the second part is a dehydration elimination reaction. First, the base abstracts the proton to form a carbanion. Then, it attacks the carbonyl group of another compound to form an oxy anion. This compound undergoes hydrolysis and forms an aldol, followed by dehydration which will give an aldol product.

Mechanism:-

(a)

(b)

Ans: Part a

The most stable product of the given reaction is:

Part b

The most stable product formed in the reaction is: