Animated Solution for Chemistry - Organic Chemistry: The formation of which of the following polymers involves hydrolysis reaction?

Welcome, future engineers and scientists! Today, we are going to embark on a fascinating journey into the world of macromolecules.

Polymers are everywhere around us, from the plastics we use daily to the DNA in our cells. Understanding how they are formed is a crucial part of organic chemistry.

In this specific problem, we are presented with a classic conceptual puzzle. We need to identify which of the given polymers requires a hydrolysis reaction during its formation process.

Let's break down what the question is really asking. Hydrolysis is a chemical reaction where water is used to break down a compound.

Therefore, we are looking for a polymer whose starting material, or monomer, is not initially ready to form a long chain. It must first be broken apart by water.

Let's evaluate our options: Nylon-6, Bakelite, Nylon-6,6, and Terylene. To solve this, we need to recall the monomers for each of these polymers.

Caprolactam

Let's start our investigation with the first option, Nylon-6. The monomer for Nylon-6 is a very unique molecule called Caprolactam.

Unlike many common monomers that are linear chains, Caprolactam is a closed loop. Specifically, it is a 7-membered cyclic amide, also known as a lactam.

Because its ends are tied up in a ring, Caprolactam molecules cannot directly link together to form a polymer chain. We need to create reactive ends first.

The Hydrolysis Step

This is exactly where the hydrolysis reaction comes into play! To make Caprolactam polymerize, we heat it in the presence of water.

The water molecule acts as a nucleophile and attacks the stable amide bond within the ring. This attack breaks the carbon-nitrogen bond, causing the ring to snap open.

This specific step—breaking the cyclic bond with water—is the hydrolysis reaction the question is asking about.

The result of this ring-opening is a straight-chain molecule called aminocaproic acid. It has an amino group at one end and a carboxylic acid group at the other.

In an aqueous environment, it often exists as a zwitterion:

Now that we have our linear monomer, aminocaproic acid, it is perfectly primed for polymerization. We heat the system further to drive the reaction.

The amino group of one molecule reacts with the carboxylic group of a neighboring molecule. This is a condensation reaction, where a water molecule is eliminated as the monomers join.

This process repeats thousands of times, forming the long, strong polymer chain that we know as Nylon-6.

Just to be absolutely sure and avoid any silly mistakes, let's quickly verify the other options.

Bakelite is formed by the condensation of phenol and formaldehyde. Nylon-6,6 is formed by the condensation of adipic acid and hexamethylenediamine.

Terylene is formed by the condensation of terephthalic acid and ethylene glycol.

All of these start with linear or separate monomers that directly undergo condensation. None of them require an initial hydrolysis step to prepare the monomer.

Our initial analysis was spot on. The formation of Nylon-6 uniquely involves a hydrolysis reaction to open the Caprolactam ring before the actual polymerization can begin.

This structural requirement makes it stand out from the other common condensation polymers.

Therefore, we can confidently conclude that the correct answer is Option (a). Keep visualizing those molecular structures, and you'll master polymer chemistry in no time!