Question

Which from following is a first stage in preparation of viscose rayon ?

• A. \(\text{Cell}-\text{OH}+\text{NaOH}\)
• B.

  

• C.

  

• D.

  

Hint:

Viscose rayon begins by treating cellulose with sodium hydroxide to make alkali cellulose.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Viscose rayon is regenerated cellulose. The process has three stages: alkali cellulose formation, xanthate formation, and regeneration of cellulose.

Step 2: Stage by stage:
Stage 1: \(\text{Cell-OH} + \text{NaOH} \rightarrow \text{Cell-ONa} + \text{H}_2\text{O}\) (alkali cellulose).
Stage 2: \(\text{Cell-ONa} + \text{CS}_2 \rightarrow \text{Cell-O-C(=S)-SNa}\) (cellulose xanthate), shown in the figure for option (D).
Stage 3: The xanthate is converted to xanthic acid (\(\text{Cell-O-C(=S)-SH}\), figure of option C), which decomposes to regenerate cellulose when extruded into an acid bath.

Step 3: Match:
Option (A) is the first stage. The figures in (B), (C) and (D) are xanthate and xanthic acid species of later stages, so they are not first.

Final Answer:
The first stage is \(\text{Cell-OH} + \text{NaOH}\), option (A). \[ \boxed{\text{Cell-OH} + \text{NaOH}} \]