Question

Consider the following reactions. \[ \text{C}_2\text{H}_2 + \text{H}_2\text{O} \xrightarrow[\text{333 K}]{\text{Hg}^{2+}/\text{H}^+} [X] \xrightleftharpoons{\text{Isomerization}} Y \] Y cannot be obtained from which of the following reactions?

• A. \(\text{CH}_3\text{COCl} + \text{H}_2 \xrightarrow{\text{Pd/BaSO}_4} \)
• B. \(\text{CH}_3\text{CH}_2\text{OH} \xrightarrow{\text{Cu}/573 K} \)
• C. \(\text{CH}_3\text{CN} + \text{SnCl}_2 + \text{HCl} \xrightarrow{} \text{X} \, \text{with} \, \text{H}_2\text{O} \)
• D. \(\text{CH}_3\text{COOH} \xrightarrow{(i) \, \text{LiAlH}_4/\text{ether}} \xrightarrow{(ii) \, \text{H}_2\text{O}} \)

Hint:

In the presence of LiAlH₄, carboxylic acids are reduced to alcohols, but they do not undergo isomerization.

Answer 1

The Correct Option is D

Reaction and Isomerization Analysis

Let's analyze each reaction:

1. Option (1): The reaction of acetyl chloride (\( \text{CH}_3\text{COCl} \)) with hydrogen in the presence of palladium on barium sulfate \( (\text{Pd}/\text{BaSO}_4) \) is a reduction reaction. This reaction produces ethanol \( (\text{CH}_3\text{CH}_2\text{OH}) \) which can undergo further reactions like isomerization.
2. Option (2): Ethanol \( (\text{CH}_3\text{CH}_2\text{OH}) \) can undergo a dehydration reaction in the presence of copper \( (\text{Cu}) \) at 573 K, forming ethene \( (\text{CH}_2=\text{CH}_2) \), which can then undergo isomerization.
3. Option (3): In this reaction, acetonitrile (\( \text{CH}_3\text{CN} \)) reacts with stannous chloride \( (\text{SnCl}_2) \) and hydrochloric acid \( (\text{HCl}) \), which can reduce the nitrile group to an amine \( (\text{CH}_3\text{CH}_2\text{NH}_2) \). This isomerization is possible.
4. Option (4): The reaction of acetic acid \( (\text{CH}_3\text{COOH}) \) with lithium aluminum hydride \( (\text{LiAlH}_4) \) in ether followed by hydrolysis with water results in the formation of ethanol \( (\text{CH}_3\text{CH}_2\text{OH}) \). However, this reaction will not directly form an isomer of the compound, and thus, the product does not undergo isomerization.

Conclusion:

Thus, Y cannot be obtained from option (4).