Question

Buna-S is obtained from

• A. Styrene and 2-chloro-1,3-butadiene
• B. Adipic acid and hexamethylene diamine
• C. Styrene and butadiene
• D. Glycine and $\varepsilon$-amino caproic acid Diesel

Hint:

Break down the trade name to find the components: Butadene + Na (Sodium catalyst) + Styrene = Buna-S. Similarly, Butadiene + Na + Acrylonitrile = Buna-N.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question requires us to identify the monomer units that undergo polymerization to produce the synthetic elastomer known as Buna-S.

Step 2: Key Formula or Approach:
Buna-S is a synthetic addition copolymer. Its name provides a direct clue to its chemical composition:

Bu stands for 1,3-butadiene.

Na stands for Sodium (Na), which acts as the polymerization catalyst.

S stands for Styrene.

Step 3: Detailed Explanation:
Buna-S (also called Styrene-Butadiene Rubber or SBR) is manufactured via the addition copolymerization of 1,3-butadiene ($\text{CH}_2\text{=CH-CH=CH}_2$) and styrene ($\text{C}_6\text{H}_5\text{CH=CH}_2$) taken in a specific $3:1$ intermolecular ratio in the presence of a sodium catalyst: $$n\ \text{CH}_2\text{=CH-CH=CH}_2 + n\ \text{C}_6\text{H}_5\text{-CH=CH}_2 \xrightarrow{\text{Na}} \text{[-CH}_2\text{-CH=CH-CH}_2\text{-CH(C}_6\text{H}_5\text{)-CH}_2\text{-]}_n$$ Evaluating other choices: Option (A) leads to Neoprene (if using chloroprene). Option (B) yields Nylon-6,6. Option (D) synthesizes the biodegradable polymer Nylon-2-nylon-6.

Step 4: Final Answer:
Buna-S is formed from styrene and butadiene, which matches option (C).