Problem 35 - A Complete Resource Book in Chemistry for JEE Main

Question

Which is used for the formation of nylon- \(6,6 ?\) (a) phthalic acid (b) sulphurous acid (c) sulphur hexafluoride (d) adipic acid

Step-by-Step Solution

Answer

(d) adipic acid

Step 1: Understanding Nylon-6,6 Formation

Nylon-6,6 is a type of polyamide that is formed through a condensation polymerization process. It is produced by reacting two specific monomers: hexamethylene diamine and adipic acid. A polymer is formed by elimination of a small molecule, such as water.

Step 2: Identifying Monomers for Nylon-6,6

To form Nylon-6,6, the monomers required are hexamethylene diamine and adipic acid. This reaction involves the amine group of hexamethylene diamine reacting with the carboxylic acid group of adipic acid.

Step 3: Analyzing the Given Options

Review the given options to identify if any correspond to adipic acid. Option (a) is phthalic acid, option (b) is sulphurous acid, option (c) is sulphur hexafluoride, and option (d) is adipic acid.

Step 4: Selecting the Correct Answer

Among the options, adipic acid (option d) is the monomer used together with hexamethylene diamine for the formation of Nylon-6,6.

Key Concepts

Understanding Condensation Polymerization

Condensation polymerization is a crucial process in the creation of many synthetic materials, such as nylons. During this type of polymerization, monomers combine by eliminating a small molecule, often water or methanol. In the case of Nylon-6,6 formation, the monomers are hexamethylene diamine and adipic acid.

• These monomers react through their functional groups
• Two molecules join end-to-end, and a byproduct, such as water, is released

This process results in long chains of molecules, forming a polymer. Each repeating unit in the polymer chain draws from both monomers.
The elimination of a small molecule is a distinguishing factor, separating condensation polymerization from other types like addition polymerization, which do not release byproducts.

The Role of Adipic Acid in Nylon-6,6

Adipic acid is fundamental to the formation of Nylon-6,6 due to its reactive functional groups. This dicarboxylic acid features two carboxyl groups (-COOH), making it highly suitable for forming strong covalent bonds with diamines such as hexamethylene diamine.

• Occurs naturally in some plants, but primarily derived synthetically for industrial purposes
• In condensation polymerization, adipic acid's carboxyl groups react with diamine groups to create an amide bond

For students, understanding the chemical reactivity of adipic acid and its ability to form bond structures is essential in explaining why it is selected over other acids, such as phthalic acid, in nylon production.

Features of Polyamides like Nylon-6,6

Polyamides are a group of polymers known for their durability and strength, widely used in textiles like nylon. Nylon-6,6, a specific polyamide, is synthesized from hexamethylene diamine and adipic acid. This polymer has a well-organized structure due to its repeating amide bonds.

• Amide bonds form the backbone of polyamides, providing notable strength and resilience
• Polyamides can be thermoplastic or thermosetting, influencing their recycling and molding properties

Nylon-6,6 is particularly valued for its thermal and chemical stability, making it ideal for industrial applications ranging from clothing to car parts. These characteristics explain its broad applications and make nylon a crucial polyamide in various sectors.