Question

Ethylene on reaction with cold, dilute alkaline \(\text{KMnO}_4\) at 273 K gives a compound 'P'. This on polymerisation with which of the following gives dacron?

• A. 1
• B. 2
• C. 3
• D. 4

Hint:

Dacron is a linear polymer made from Terephthalic acid (para). Glyptal is a cross-linked polymer made from Phthalic acid (ortho). Both use Ethylene Glycol.

Answer 1

The Correct Option is B

Step 1: Identify Product P: Reaction of Ethylene with cold, dilute alkaline \(\text{KMnO}_4\) (Baeyer's Reagent) leads to syn-hydroxylation. \(\text{CH}_2=\text{CH}_2 + \text{H}_2\text{O} + [\text{O}] \rightarrow \text{HO-CH}_2\text{-CH}_2\text{-OH}\). Product P is Ethylene Glycol.
Step 2: Identify Monomers of Dacron: Dacron (Terylene) is a polyester formed by the condensation polymerization of: 1. Ethylene Glycol (Ethane-1,2-diol). 2. Terephthalic Acid (Benzene-1,4-dicarboxylic acid).
Step 3: Analyze Options: -

(A) Benzoic acid: Monocarboxylic acid. - (B) Terephthalic acid: 1,4-dicarboxylic acid (Para isomer). This matches. - (C) Phthalic acid: 1,2-dicarboxylic acid (Ortho isomer). Used for Glyptal. - (D) p-Hydroxybenzoic acid.
Required Answer: Option (B).