Question

The product ’P’ in the above reaction is:

• A. \(Ph CH=CHCH_2COOH\)
• B.
• C.
• D.

Answer 1

The Correct Option is B

The reaction shown involves a Wittig reaction. The Wittig reaction is a chemical reaction used in organic chemistry to convert a carbonyl group (aldehyde or ketone) to an alkene using a phosphonium ylide. Let's analyze the reactants and predict the product.

The reactants are: 

1. A phosphonium ylide derived from \(PhCH_2P^+Ph_3 Br^-\) after treatment with a base. This ylide is stabilized.

2. 4-oxo-pentanoic acid

The Wittig reaction proceeds as follows:

The ylide attacks the carbonyl carbon of the 4-oxo-pentanoic acid. This forms a betaine intermediate, which then cyclizes to form an oxaphosphetane. This oxaphosphetane then breaks down to form the alkene and triphenylphosphine oxide. The key is to identify the correct alkene that forms.

The ylide \(Ph-CH=P(Ph)_3\) will react with the ketone group of the 4-oxo-pentanoic acid. The double bond will form between the carbon that was part of the carbonyl group and the carbon attached to the phenyl group in the ylide. Therefore, the product will have the structure:

 

The correct product 'P' is:

Answer 2

This reaction is a Perkin condensation reaction. Benzaldehyde (PhCHO) reacts with acetic anhydride in the presence of a base (sodium ethoxide) to produce cinnamic acid \(\text{Ph} - \text{CH} = \overset{\text{CH}_3}{\text{C}} - \text{COOH}\).
The reaction proceeds through the formation of an enolate ion, followed by aldol-like condensation and dehydration to yield the α, β-unsaturated carboxylic acid product.