Question

The correct sequence of reagents for the above conversion of X to Y is :

• A. (i) NaOH (aq) (ii) Jones reagent (iii) H₃O⁺
• B. (i) NaOEt (ii) B₂H₆/H₂O₂ (iii) Jones reagent
• C. (i) B₂H₆/H₂O₂ (ii) NaOEt (iii) Jones reagent
• D. (i) Jones reagent (ii) NaOEt (iii) Hot KMnO₄/KOH

Hint:

Jones reagent ($CrO_3/H_2SO_4$) is a strong oxidant that will take a primary alcohol all the way to a carboxylic acid.

Answer 1

The Correct Option is B

To convert compound X to compound Y, we need to understand the sequence of chemical transformations involved.

The compound X is an aryl bromide with the structure:

\(\text{C}_6\text{H}_5\text{CHBrCH}_3\).

The compound Y is a benzoic acid with the structure:

\(\text{C}_6\text{H}_5\text{CH}_2\text{COOH}\).

1. First, we use NaOEt to replace the bromine atom with an ethoxide group, forming an alkene through elimination. This step is a typical E2 elimination reaction.
2. Next, we use B₂H₆/H₂O₂ for hydroboration-oxidation. This reaction converts the alkene into an alcohol by anti-Markovnikov hydration, resulting in a primary alcohol.
3. Lastly, we employ the Jones reagent (CrO₃ in acid) to oxidize the alcohol to a carboxylic acid. This step completes the conversion to the desired benzoic acid.

The correct sequence for converting X to Y is therefore:

(i) NaOEt (ii) B₂H₆/H₂O₂ (iii) Jones reagent

This sequence is consistent with the elimination, hydration, and oxidation steps required to convert the starting material into the final carboxylic acid product.