Question

Amongst the following, hydrolytic desizing agents attack starch at:

• A. \( \alpha - 1, 4 \) glucosidic linkage
• B. Six membered ring
• C. Hydroxyl group
• D. Carboxyl group

Hint:

- Hydrolytic desizing agents target the \( \alpha - 1, 4 \) glucosidic linkage between glucose units in starch.
- Breaking these bonds leads to the breakdown of starch into smaller molecules that can be removed from fabrics.

Answer 1

The Correct Option is A

Hydrolytic desizing is a process in textile manufacturing used to remove sizing agents, such as starch, from the fabric. Starch is a polysaccharide made up of glucose units connected by glycosidic bonds. When desizing agents act on starch, they hydrolyze these glycosidic bonds, breaking down the starch into smaller units.
To understand why the desizing agents attack the starch at a specific location, let's go over the details of the starch structure and the role of hydrolytic agents: 1) Starch Structure: Starch consists of two main components: amylose and amylopectin. Both are made up of glucose molecules. The glucose units are linked by \( \alpha - 1, 4 \) glycosidic bonds. In amylopectin, there are also \( \alpha - 1, 6 \) bonds at branch points. 2) Action of Hydrolytic Agents: Hydrolytic desizing agents target the \( \alpha - 1, 4 \) glucosidic linkage, which is the primary bond between glucose units in starch. By breaking these bonds, the hydrolytic agents reduce the starch polymer into smaller, soluble units, which can then be easily removed from the fabric. 3) Other Bond Locations: While the \( \alpha - 1, 6 \) glucosidic bond occurs in amylopectin, it is not the primary target of hydrolytic desizing agents. Hydroxyl groups and carboxyl groups, although present in the starch molecules, are not directly involved in the attack by hydrolytic desizing agents. Thus, hydrolytic desizing agents specifically attack the \( \alpha - 1, 4 \) glucosidic linkage in starch. Explanation of other options: - (B) The six-membered ring refers to the glucose molecule's structure, but it is not where the desizing agents act. - (C) The hydroxyl group is present on the glucose units, but it is not the site of attack by hydrolytic agents. - (D) The carboxyl group is a functional group found in acids, and it does not play a role in the hydrolysis of starch. Therefore, the correct answer is (A) \( \alpha - 1, 4 \) glucosidic linkage.