Problem 82 - Advanced Problems in Organic Chemistry for Competitive Examinations

Question

PVC polymer can be prepared by which of the monomers? (a) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl}\) (b) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}=\mathrm{CH}_{2}\) (c) \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}\) (d) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}\)

Step-by-Step Solution

Answer

PVC is prepared from the monomer \\( \mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl} \).

Step 1: Understand PVC

PVC stands for Polyvinyl Chloride, which is a polymer made from repeating units of a particular monomer. The structure of PVC includes repeating units derived from the vinyl chloride monomer, which has a chlorine atom bonded to the carbon chain.

Step 2: Identify the Required Monomer

To form PVC, we need a monomer containing a vinyl group where one of the hydrogen atoms is replaced by a chlorine atom. This corresponds to the chemical structure \\( \mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl} \).

Step 3: Compare Options

Now, compare each of the given options with the structure of the vinyl chloride monomer. (a) is \\( \mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl} \), which directly matches the structure of the monomer used to prepare PVC. The other options (b), (c), and (d) have different structural compositions and cannot form PVC.

Key Concepts

Understanding Vinyl Chloride

Vinyl chloride is a crucial monomer in the synthesis of PVC, which stands for polyvinyl chloride. It's a simple organic compound represented by the formula \( \mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl} \). In its structure, it possesses a vinyl group—two carbon atoms double-bonded—with one chlorine atom attached to the first carbon.

This particular arrangement of atoms allows vinyl chloride to polymerize, meaning it can form long chains by joining with other similar molecules. In the context of PVC polymerization, the chlorine atom is significant because it affects the properties of the resulting polymer, influencing its durability and resistance to chemical stresses.

Vinyl chloride is a colorless gas at room temperature and has distinct properties useful in both its production and application. For example, its ability to undergo addition polymerization makes it valuable for creating PVC. This polymer is versatile, used in various products from pipes to clothing thanks to the characteristics imparted by the incorporated chlorine atoms.

The Role of Monomers in Polymer Chemistry

Monomers are small molecules that can join together to form polymers, larger and more complex structures. In polymer chemistry, the focus is often on how these simple building blocks, such as vinyl chloride, interact and combine to produce materials with specific characteristics.

Monomers like vinyl chloride are important because they determine the physical and chemical properties of the resultant polymer. For instance, in the PVC production process, thousands of vinyl chloride units link together in a reaction known as polymerization. This reaction typically involves initiators that help to start the chain reaction leading to the formation of the polymer.

During polymerization, the double bond in the monomer opens, allowing it to connect to another monomer. This forms a long chain, repeating the monomer unit, along with variations made possible by any substituents included in the monomer's structure. Understanding the behavior and characteristics of monomers under different conditions is crucial for advancing polymer technologies and applications.

Tackling Organic Chemistry Problems

Organic chemistry problems often revolve around understanding molecular structures and reactions. Inquiries like identifying which monomer can form a particular polymer, such as PVC, require a keen eye on structural details.

Let's take the example from the exercise. To solve it, it's essential to identify the distinct features in each monomer option. For PVC, it's the presence of a chlorine atom on the vinyl group. This unique configuration signifies the potential for forming the desired polymer, which can be easily missed without careful inspection.

Approaching organic chemistry problems involves not just recognizing names but also appreciating the nuances in each molecular formula and structure. These problems test your understanding of how different atoms and functional groups affect molecular behavior, leading to precise applications in industries like pharmaceuticals, plastics, and more.

By practicing these problem-solving skills, you refine your ability to analyze and predict chemical reactions and properties, bolstering your understanding of organic chemistry as a whole.