Question

Which is the most suitable reagent for the following conversion ?

• A. Tollen’s reagent
• B. Benzoyl peroxide
• C. I₂ and NaOH solution with subsequent acidification
• D. Sn and NaOH solution

Answer 1

The Correct Option is C

To solve this problem, we need to identify the suitable reagent for the given conversion.

1. Understanding the Reaction:
The reaction involves the oxidation of a compound with an alkene group (CH₃-CH=CH-CH₂-COCH₃). The product shows a carboxylic acid group (-COOH) on the terminal carbon. This suggests that the compound undergoes oxidation at the position of the alkene group (double bond), converting it to a carboxyl group.

2. Analyzing the Reagents:
Let's evaluate the possible reagents that could effect this transformation:

• Option (A) "Tollen's reagent": Tollen's reagent, which contains silver(I) ions (Ag⁺), is typically used to oxidize aldehydes to carboxylic acids, but it does not oxidize alkenes. Thus, this reagent is not suitable for this transformation.
• Option (B) "Benzoyl peroxide": Benzoyl peroxide is a radical initiator and is commonly used in the polymerization of alkenes. It can also initiate the formation of alkyl radicals, but it does not directly oxidize alkenes to carboxylic acids. This is not the correct choice for this conversion.
• Option (C) "I₂ and NaOH solution with subsequent acidification": This is a typical reaction for the oxidative cleavage of alkenes. The iodine (I₂) and NaOH solution will cleave the double bond of the alkene, and after acidification, a carboxylic acid is formed. This is a suitable reagent for the transformation described in the problem.
• Option (D) "Sn and NaOH solution": This combination is typically used for the reduction of carbonyl groups (e.g., in the reduction of aldehydes and ketones), not for the oxidation of alkenes. Thus, it is not suitable for this reaction.

Final Answer:
The most suitable reagent for this conversion is (C) "I₂ and NaOH solution with subsequent acidification," as it is used for the oxidative cleavage of alkenes to form carboxylic acids.

Answer 2

The given reaction involves the conversion of an α,β-unsaturated carbonyl compound (CH₃CH=CHCOCH₃) into a β-hydroxy ketone (CH₃CH=CHCOOH) through an aldol-like reaction. This type of conversion is a typical reaction of an enone with iodine in an alkaline medium, followed by acidification. This is known as the iodoform test or iodine in alkaline solution, which results in the formation of a β-hydroxy ketone and the release of iodine in the process.

The mechanism involves the formation of an enolate ion under the basic conditions provided by NaOH, which then reacts with I₂ to form the desired product.

The correct answer is (C) : I₂ and NaOH solution with subsequent acidification.