What are the monomeric units of Glyptal?

Ethylene glycol + Phthalic acid

The correct answer is option 1. Ethylene glycol + Phthalic acid.

Glyptal is a type of resin that belongs to the family of alkyd resins. It is formed through a condensation polymerization reaction between two main monomeric units: ethylene glycol and phthalic acid.

Here is a detailed explanation of the monomeric units of Glyptal:

1. Ethylene Glycol (also known as ethane-1,2-diol): Ethylene glycol is a simple diol compound with two hydroxyl (OH) groups attached to adjacent carbon atoms. Its chemical formula is \( \text{HOCH}_2\text{CH}_2\text{OH} \). Ethylene glycol is commonly used as a reactant in the synthesis of various polymers and resins due to its ability to undergo condensation reactions with carboxylic acids, such as phthalic acid.

2. Phthalic Acid: Phthalic acid is a dicarboxylic acid with the chemical formula \( \text{C}_6\text{H}_4(\text{COOH})_2 \). It contains two carboxylic acid (COOH) functional groups attached to a benzene ring. Phthalic acid is often used in the synthesis of resins and polymers due to its ability to react with diols, such as ethylene glycol, to form ester linkages.

The reaction between ethylene glycol and phthalic acid involves the condensation of the hydroxyl group (-OH) of ethylene glycol with one of the carboxylic acid groups (-COOH) of phthalic acid, resulting in the formation of an ester linkage. This process repeats, leading to the formation of long chains of repeating units, which constitute the Glyptal resin.

The chemical structure of Glyptal resin consists of alternating ester linkages between the ethylene glycol and phthalic acid units. This structure imparts desirable properties to Glyptal, including good adhesion, chemical resistance, and mechanical strength, making it suitable for various applications such as coatings, paints, adhesives, and insulating materials.

In summary, Glyptal is formed by the condensation polymerization of ethylene glycol and phthalic acid, resulting in the formation of a resin with valuable properties for industrial and commercial use.