Question

The solvent used in Wurtz reaction is ________.

• A. Water
• B. Methanol
• C. Ethanol
• D. Dry ether
• E. Aqueous ethanol

Hint:

"Dry" ether means it is free from any traces of water.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
The Wurtz reaction is a coupling reaction used to synthesize alkanes by reacting an alkyl halide with sodium metal. The choice of solvent is crucial because of the high reactivity of sodium.
Step 2: Key Formula or Approach
The general equation for the Wurtz reaction is: \[ 2R-X + 2Na \xrightarrow{\text{solvent}} R-R + 2NaX \] The key is to understand the properties of the reagent, sodium (Na). Sodium is a very strong reducing agent and is highly reactive towards any compound with acidic protons (protic compounds).
Step 3: Detailed Explanation
1. Reactivity of Sodium:
Sodium metal reacts violently with protic solvents like water and alcohols. These solvents contain -OH groups with acidic hydrogen atoms. - Reaction with water: \(2Na(s) + 2H_2O(l) \to 2NaOH(aq) + H_2(g)\) (This reaction is exothermic and often ignites the hydrogen gas produced). - Reaction with ethanol: \(2Na(s) + 2C_2H_5OH(l) \to 2C_2H_5ONa(aq) + H_2(g)\)
If any of these solvents were used, the sodium would be consumed in a side reaction with the solvent rather than reacting with the alkyl halide. 2. Requirement for the Solvent:
Therefore, the solvent for the Wurtz reaction must be: - Aprotic: It must not have any acidic protons that can react with sodium. - Anhydrous (Dry): It must be completely free of water. 3. Evaluating the Options:
- (A) Water, (B) Methanol, (C) Ethanol, (E) Aqueous ethanol are all protic solvents and would react with sodium. - (D) Dry ether (usually diethyl ether, \(CH_3CH_2OCH_2CH_3\)) is an aprotic solvent. It does not have acidic protons and does not react with sodium. When used in its "dry" or anhydrous form, it is the ideal solvent for the Wurtz reaction.
Step 4: Final Answer
The solvent used in the Wurtz reaction is dry ether.