Question

Identify the monomers use to prepare glyptal.

• A. $\beta$-Hydroxy butyric acid and $\beta$-hydroxy valeric acid
• B. Ethylene glycol and phenol
• C. Ethylene glycol and terephthalic acid
• D. Ethylene glycol and phthalic acid

Hint:

Phthalic acid (ortho) $\rightarrow$ Glyptal (used in paints). Terephthalic acid (para) $\rightarrow$ Terylene (used in clothes).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Glyptal is a well-known type of polyester resin. Polyesters are synthesized by the step-growth condensation polymerization of dicarboxylic acids and diols. We must correctly identify the specific constituent monomers for glyptal.
Step 2: Key Formula or Approach:
Approach: Recall the specific monomer combinations that form common commercial polymers like PHBV, Bakelite, Terylene, and Glyptal.
Step 3: Detailed Explanation:
Let's carefully analyze the polymers formed by the monomer pairs given in the options: - (A) $\beta$-Hydroxy butyric acid and $\beta$-hydroxy valeric acid: These two monomers copolymerize to form PHBV, which is a notable biodegradable polyester. - (B) Ethylene glycol and phenol: These monomers do not standardly undergo condensation polymerization with each other. Phenol typically polymerizes with formaldehyde to form Bakelite. - (C) Ethylene glycol and terephthalic acid: The condensation polymerization of these two monomers yields Terylene (also widely known as Dacron). Terephthalic acid is the para-isomer of phthalic acid. - (D) Ethylene glycol and phthalic acid (or phthalic anhydride): The condensation of ethylene glycol (ethane-1,2-diol) and phthalic acid (benzene-1,2-dicarboxylic acid, the ortho-isomer) yields the cross-linked polyester known as Glyptal. It forms an alkyd resin utilized primarily in the manufacture of paints and lacquers.
Step 4: Final Answer:
The correct monomers are ethylene glycol and phthalic acid.