MCQ Detailed View

Ethanol (C₂H₅OH) reacts with concentrated sulfuric acid (H₂SO₄) under different conditions to produce various products. Sulfuric acid acts both as a dehydrating agent and as a protonating acid, promoting reactions that lead to different organic compounds. However, acetylene (C₂H₂) is not one of the products formed in these reactions.

1️⃣ Formation of Ethyl Hydrogen Sulphate:
At around room temperature (20–25°C), ethanol reacts with concentrated H₂SO₄ to produce ethyl hydrogen sulfate (C₂H₅OSO₃H). This is an esterification reaction where sulfuric acid acts as a proton donor and combines with ethanol.
Reaction: C₂H₅OH + H₂SO₄ → C₂H₅OSO₃H + H₂O

2️⃣ Formation of Diethyl Ether:
When the reaction is heated to about 140°C, two molecules of ethanol condense in the presence of H₂SO₄ to form diethyl ether (C₂H₅OC₂H₅) and water. This is a dehydration reaction under controlled conditions.
Reaction: 2C₂H₅OH → C₂H₅OC₂H₅ + H₂O

3️⃣ Formation of Ethene:
At a higher temperature of about 170°C, concentrated H₂SO₄ removes water from ethanol, producing ethene (C₂H₄) gas.
Reaction: C₂H₅OH → C₂H₄ + H₂O

4️⃣ Why Not Acetylene?
Acetylene (C₂H₂) is not formed in any reaction of ethanol with concentrated sulfuric acid. Acetylene is typically produced by other processes, such as partial combustion of methane or reaction of calcium carbide with water, not by ethanol dehydration.

Therefore, among the options given, the reaction of ethanol with conc. H₂SO₄ does not produce acetylene, making Option 3 (Acetylene) the correct answer.