Question

The compound with which hexamethylene diamine on polymerization gives nylon- 6,6 is:
A. Citric acid
B. Adipic acid
C. Oxalic acid
D. Tartaric acid

Answer 1

Nylon-$6,6$ is a type of polyamide which is synthesized by polycondensation reaction by adding two different monomers each having six carbon atoms.

Step by step answer: Hexamethylenediamine is an organic diamine compound having hexamethylene as a hydrocarbon chain terminated with the functional group amine. Its molecular formula is ${H_2}N{(C{H_2})_6}N{H_2}$ .
when this polymerisation reaction between hexamethylenediamine and another monomer of adipic acid takes place under the influence of high pressure and high temperature a compound nylon-$6,6$is synthesized. Since both the monomers have six carbon atoms it is named as $6,6$nylon.

Adipic acid is an organic compound with hexanedioic acid. It is a diacidic compound having two acidic groups in it. Its molecular formula is ${(C{H_2})_4}{(COOH)_2}$
The reaction takes place like following:

$nHOOC - {(C{H_2})_4} - COOH + n{H_2}N - {(C{H_2})_6} - N{H_2} \to {[ - OC - {(C{H_2})_4} - CO - NH - {(C{H_2})_6} - NH - ]_n}$

When the equivalent amount of and adipic acid are combined with water in a reaction mix a crystal salt of nylon are formed. These nylon salts are ammonium/carboxylate mixtures. The reaction involves the removal of water molecules leading the polymerization to take place through the formation of amide bonds from the acid and amine group present in the reactants. The molten 66 formed is extracted by cooling down the molten 66 to form solid fragments of nylon-$6,6$.

Additional information: Nylon-$6,6$is most commonly used for the textile and plastic industry. It is used when high mechanical strength, rigidity and stability are required. It is also commonly used in the fiber used for textiles and carpets.

Note: The polycondensation reaction is the one in which the polymers are joined together via condensation reaction via losing water or methanol as a bi-product. The Nylon 6,6 formed is in molten state .This molten 66 formed is extracted by cooling down the molten 66 to form solid fragments of nylon-$6,6$.