Problem 88 - A Complete Resource Book in Chemistry for JEE Main

Question

In the following reaction Cellulose \(\stackrel{\text { (i) } \mathrm{CS}_{2} / \mathrm{NaOH}}{\text { (ii) } \mathrm{HCl} / \mathrm{HOH}}-[\mathrm{P}]\) Here, the product [P] is (a) rayon (b) cellulose acetate (c) gun cotton (d) cellulose xanthate

Step-by-Step Solution

Answer

The product [P] is (a) rayon.

Step 1: Analyzing the Provided Reaction

The reaction in question involves cellulose reacting with certain chemicals in two steps. In the first step, cellulose reacts with carbon disulfide \(\mathrm{CS}_2\) and sodium hydroxide \(\mathrm{NaOH}\). Then, it undergoes a second step with hydrochloric acid \(\mathrm{HCl}\) and water (\(\mathrm{HOH}\)).

Step 2: Understanding the First Reaction Step

In the first step, cellulose is treated with \(\mathrm{CS}_2\) and \(\mathrm{NaOH}\). This step converts cellulose into a compound known as cellulose xanthate, which is a precursor for the substance Rayon.

Step 3: Analyzing the Second Reaction Step

During the second step, the cellulose xanthate is treated with \(\mathrm{HCl}\) and \(\mathrm{HOH}\) (water). This process is necessary to regenerate cellulose from cellulose xanthate, leading to the production of a new form: rayon fibers.

Step 4: Conclusion on Produced Compound

The two-step chemical reaction sequence is typically used in the industrial production of rayon, a textile fiber made by regenerating cellulose. This confirms that the product '[P]' of this reaction is indeed rayon.

Key Concepts

Cellulose Xanthate

Cellulose xanthate plays a vital role in the production of rayon. It is a compound formed when cellulose, a natural polymer found in the cell walls of plants, reacts chemically with carbon disulfide (\(\mathrm{CS}_2\)) in the presence of sodium hydroxide (\(\mathrm{NaOH}\)). This reaction alters the structure of cellulose, making it soluble in water.

The significance of cellulose xanthate lies in its ability to be transformed back into cellulose via controlled chemical processes. It is this transformation that is crucial for creating rayon fibers. Understanding how cellulose xanthate acts as an intermediary in the production of rayon helps us grasp why this compound is essential for turning natural cellulose into usable textile fibers.

Chemical Reaction Steps

The production of rayon involves a two-step chemical process where cellulose undergoes significant changes. Let's break down these steps to better understand how they contribute to making rayon from natural materials.

- **First Step**: - Cellulose is combined with carbon disulfide (\(\mathrm{CS}_2\)) and sodium hydroxide (\(\mathrm{NaOH}\)). - This mixture results in the formation of cellulose xanthate. This compound is integral because it makes cellulose soluble, which is necessary for forming fibers.- **Second Step**: - The cellulose xanthate solution is then treated with hydrochloric acid (\(\mathrm{HCl}\)) and water (\(\mathrm{HOH}\)). - This treatment regenerates cellulose from cellulose xanthate, forming rayon fibers.

Understanding these steps reveals how chemical reactions are employed to modify natural materials, producing synthetic fiber materials with desirable textile properties.

Textile Fibers

Textile fibers like rayon are valued for their versatility and smooth texture. Rayon, which emerges from processing cellulose, offers properties similar to natural fibers such as cotton and silk. Yet, it also bridges the gap to synthetic fibers. Let's dive into why textile fibers such as rayon are essential in the industry.

- **Properties**: - Rayon fibers are soft, absorbent, and comfortable to wear, making them a popular choice for garments and home furnishings. - They mimic the texture of natural fibers but come with the flexibility of synthetic production methods. - **Applications**: - Due to their properties, rayon is used in clothing, upholstery, and various home decor items. - The ability to control their attributes through chemical processes makes rayon a preferred choice in many applications.

Recognizing the importance of rayon and other textile fibers helps appreciate how chemistry transforms raw natural materials into refined, usable forms that play a crucial role in our daily lives.