Question

Given below are two statements: 
Statement (I): Alcohols are formed when alkyl chlorides are treated with aqueous potassium hydroxide by elimination reaction. 
Statement (II): In alcoholic potassium hydroxide, alkyl chlorides form alkenes by abstracting the hydrogen from the $ \beta $-carbon. 
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are incorrect
• B. Statement I is incorrect but Statement II is correct
• C. Statement I is correct but Statement II is incorrect
• D. Both Statement I and Statement II are correct

Hint:

Elimination and substitution reactions are key processes for forming alkenes and alcohols, respectively, based on the conditions (e.g., solvent, temperature).

Answer 1

The Correct Option is B

To address this question, we must evaluate the provided statements concerning the reactions of alkyl chlorides with potassium hydroxide solutions.

1. Analysis of Statement I:
   • This statement asserts that alcohols are produced from the reaction of alkyl chlorides with aqueous potassium hydroxide via an elimination reaction.
   • This assertion is erroneous. While aqueous potassium hydroxide does yield alcohols from alkyl chlorides, the mechanism is a substitution reaction, not elimination. The hydroxide ion (\( \text{OH}^- \)) substitutes the chloride ion (\( \text{Cl}^- \)), forming alcohols.
   • The corresponding reaction is represented as: \(R-\text{Cl} + \text{KOH(aq)} \rightarrow R-\text{OH} + \text{KCl}\)
2. Analysis of Statement II:
   • This statement proposes that alkyl chlorides generate alkenes in the presence of alcoholic potassium hydroxide by abstracting hydrogen from the \( \beta \)-carbon.
   • This assertion is accurate. Alcoholic KOH induces elimination in alkyl chlorides, leading to the formation of alkenes. This is a dehydrohalogenation reaction, characterized by the removal of hydrogen from the \( \beta \)-carbon and the formation of a double bond.
   • The reaction is depicted as: \(R-\text{CH}_2-\text{CH}\text{Cl}-R' + \text{KOH(alc)} \rightarrow R-\text{CH}=\text{CH}-R' + \text{KCl} + \text{H}_2\text{O}\)

Based on these analyses:

• Statement I is incorrect due to the misidentification of the reaction mechanism (elimination instead of substitution) in alcohol formation.
• Statement II is correct as it accurately describes the elimination process yielding alkenes.

Therefore, the correct conclusion is: Statement I is incorrect, while Statement II is correct.