Problem 46 - Advanced Problems in Organic Chemistry for Competitive Examinations

Question

Buna-N synthetic rubber is a copolymer of (a) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\stackrel{\mathrm{Cl}}{\mathrm{C}}=\mathrm{CH}_{2}\) and \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_{2}\) (b) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_{2}\) and \(\mathrm{H}_{5} \mathrm{C}_{6}-\mathrm{CH}=\mathrm{CH}_{2}\) (c) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CN}\) and \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_{2}\) (d) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CN}\) and \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{Cl}=\mathrm{CH}_{2}\)

Step-by-Step Solution

Answer

Option (c) is the correct answer: \\(\text{H}_2\text{C}=\text{CH}-\text{CN}\\) and \\(\text{H}_2\text{C}=\text{CH}-\text{CH}=\text{CH}_2\\).

Step 1: Identify Buna-N Rubber Components

Buna-N, also known as nitrile rubber, is a synthetic rubber copolymer. The copolymer consists of acrylonitrile (ACN) and butadiene in varying proportions.

Step 2: Find Acrylonitrile from Options

The chemical formula for acrylonitrile is \(\text{H}_2\text{C}=\text{CH}-\text{CN}\). Look through the given options to find this component.

Step 3: Find Butadiene from Options

Butadiene has the chemical structure \(\text{H}_2\text{C}=\text{CH}-\text{CH}=\text{CH}_2\). Identify this component in the available options to pair with acrylonitrile.

Step 4: Match Components to Correct Option

Both acrylonitrile \(\text{H}_2\text{C}=\text{CH}-\text{CN}\) and butadiene \(\text{H}_2\text{C}=\text{CH}-\text{CH}=\text{CH}_2\) are present in option (c). Therefore, option (c) is the correct choice for Buna-N synthetic rubber composition.

Key Concepts

Synthetic Rubber

Did you know that synthetic rubber is a man-made material widely used in everyday products like tires, seals, and gaskets? Synthetic rubber was developed as a result of natural rubber shortages during the early 20th century. It has properties similar to natural rubber but can be customized to enhance specific characteristics. This makes it highly valuable in industrial applications.

• Durability: Synthetic rubber is known for its ability to withstand extreme conditions.
• Versatility: It can be tailored to meet the requirements of different industries.
• Production: Unlike natural rubber, which is harvested from rubber trees, synthetic rubber is produced using petrochemical processes.

Understanding synthetic rubber opens up a world of chemistry that involves the creation of materials with desired properties by manipulating molecular structures.

Copolymer

Copolymer refers to a polymer that is made up of two or more different types of monomers. This diversity of monomers allows for the creation of materials with specialized properties, which is why copolymers are crucial in the synthesis of everyday materials like plastics and fibers.
In the case of Buna-N, the copolymer is an amalgamation of two monomers, acrylonitrile, and butadiene. The combination of these monomers results in a material with excellent oil resistance and tensile strength, which is essential for applications in protective gloves and automotive seals.

• Diverse Monomers: Copolymers can be customized to possess a variety of characteristics.
• Application Specific: Depending on the monomers used, they can be designed for specific uses.
• Enhancement: Copolymers can improve mechanical and chemical properties.

Copolymerization demonstrates the incredible flexibility of chemistry in creating innovative materials tailored for specific functions.

Acrylonitrile

Acrylonitrile is one of the key monomers in the formation of the copolymer known as Buna-N. It is characterized by its chemical formula: \(\text{H}_2\text{C}=\text{CH}-\text{CN}\). This compound plays a vital role in chemically engineering materials to have resistance against chemicals and oil.
Acrylonitrile alone is used in various industries, including the production of plastics and fibers such as acrylics.

• Usage: It's a building block in making synthetic rubbers.
• Properties: Provides increased resistance to oils and chemicals.
• Industrial Relevance: Used in making a variety of polymers to meet demanding industrial standards.

The role of acrylonitrile in synthetic rubber highlights its significance in enhancing the durability and applicability of polymer materials.

Butadiene

Butadiene, a simple alkene with the chemical structure \(\text{H}_2\text{C}=\text{CH}-\text{CH}=\text{CH}_2\), is an essential ingredient in creating synthetic rubber such as Buna-N. It provides the elasticity and flexibility needed for rubber applications.
This compound not only contributes to the elasticity of synthetic rubber but also boosts its resistance to wear and tear. Butadiene is fundamental in the manufacture of various types of synthetic rubbers like Styrene-Butadiene Rubber (SBR), which is extensively used in the tire industry.

• Flexibility: Butadiene contributes to the elasticity of synthetic rubber.
• Application: Widely used in the production of tires and other automotive applications.
• Stability: Key to maintaining the durability of rubber under stress.

The presence of butadiene in copolymers like Buna-N emphasizes its vital role in creating high-performance rubber materials used globally.