Question

Which of the following carboxylic acid is used in the manufacture of nylon-6,6?

• A. Ethanedioic acid
• B. Propanedioic acid
• C. Butanedioic acid
• D. Pentanedioic acid
• E. Hexanedioic acid

Hint:

Nylon-6 is made from caprolactam (a cyclic amide with 6 carbons). Nylon-6,6 is made from two 6-carbon monomers.

Answer 1

Answer: (E)

Step 1: Understanding the Concept:
Nylon-6,6 is a type of polyamide, a condensation polymer. The name "6,6" indicates that it is formed from two monomers, each containing six carbon atoms. We need to identify the dicarboxylic acid monomer.
Step 2: Detailed Explanation:
The two monomers used in the synthesis of Nylon-6,6 are:
Hexamethylenediamine: A diamine with six carbon atoms. Its structure is H\(_2\)N-(CH\(_2\))\(_6\)-NH\(_2\).
Adipic acid: A dicarboxylic acid with six carbon atoms.
We need to find the IUPAC name for adipic acid. Let's name the given dicarboxylic acids:
(A) Ethanedioic acid: HOOC-COOH (2 carbons). Common name: Oxalic acid.
(B) Propanedioic acid: HOOC-CH\(_2\)-COOH (3 carbons). Common name: Malonic acid.
(C) Butanedioic acid: HOOC-(CH\(_2\))\(_2\)-COOH (4 carbons). Common name: Succinic acid.
(D) Pentanedioic acid: HOOC-(CH\(_2\))\(_3\)-COOH (5 carbons). Common name: Glutaric acid.
(E) Hexanedioic acid: HOOC-(CH\(_2\))\(_4\)-COOH (6 carbons). Common name: Adipic acid.
The polymerization reaction involves the formation of an amide bond between the amine group of one monomer and the carboxylic acid group of the other monomer, with the elimination of a water molecule. \[ n \text{ H}_2\text{N}(\text{CH}_2)_6\text{NH}_2 + n \text{ HOOC}(\text{CH}_2)_4\text{COOH} \rightarrow \left[ -\text{NH}(\text{CH}_2)_6\text{NHCO}(\text{CH}_2)_4\text{CO}- \right]_n + 2n \text{ H}_2\text{O} \] Thus, the six-carbon dicarboxylic acid required is hexanedioic acid (adipic acid).
Step 3: Final Answer:
The carboxylic acid used in the manufacture of nylon-6,6 is hexanedioic acid. This corresponds to option (E).