Problem 52 - A Complete Resource Book in Chemistry for JEE Main

Question

Cellulose is a condensation polymer of (a) \(\alpha\)-galactose (b) \(\alpha\)-glucose (c) \(\beta\)-glucose (d) \(\beta\)-galactose

Step-by-Step Solution

Answer

Cellulose is a condensation polymer of (c) \(\beta\)-glucose.

Step 1: Understand the Definition of Cellulose

Cellulose is a naturally occurring polymer found in plant cell walls. It is composed of sugar molecules bonded together in a specific manner.

Step 2: Identify the Monomer of Cellulose

The monomer of cellulose is a sugar. Specifically, it is a type of glucose molecule that has a specific configuration of its hydroxyl (-OH) groups.

Step 3: Determine the Configuration Required for Cellulose

The specific glucose that forms cellulose is in the  configuration due to the orientation of the hydroxyl group on the first carbon. The correct form needs the opposite orientation to . Identify whether it is  glucose, which the plant can use to form cellulose.

Step 4: Conclude the Type of Glucose in Cellulose

Cellulose is formed from -glucose monomers. These glucose molecules are linked through  bonds to form the long chain networks that establish cellulose's structure.

Key Concepts

Condensation Polymer

A condensation polymer is a type of polymer that forms through a specific chemical process. During the creation of these polymers, smaller molecules, often water, are released in a process called condensation. This is different from other polymerization methods, like addition polymerization, where no small byproducts are created.

Condensation polymers are essential in biology and materials science. These polymers include proteins, nylon, and cellulose. The formation occurs when two monomers join, typically with a molecule like water or methanol released.

• Monomers link together, releasing a small molecule.
• This process repeats to create long polymer chains.

By understanding condensation polymerization, one can grasp how essential natural substances like cellulose are synthesized. Cellulose specifically forms when beta-glucose monomers join in a condensation reaction, emphasizing the role of this process in plant structure.

Beta-Glucose

Beta-glucose is a specific form or isomer of glucose, which is one of the simple sugars that are vital to life. Glucose can exist in multiple forms, notably 1;-glucose and 1;-glucose, which differ in the arrangement of atoms around their asymmetric carbon.

In beta-glucose, the hydroxyl group on the first carbon atom is positioned above the plane of the sugar ring in a Haworth projection. This configuration is crucial in cellulose's structure.

• Beta-glucose molecules form the building blocks of cellulose.
• Their configuration allows the formation of tight, linear chains capable of forming strong fibers.

These fibers give plant cell walls their strength, a feature that is crucial for plant rigidity and growth.

Monomer Configuration

The configuration of a monomer affects how it interacts with other monomers to form polymers. For cellulose, beta-glucose's specific structure determines its ability to form these long chains.

Monomer configuration refers to the spatial arrangement of atoms in a molecule that remains consistent during polymerization. This configuration is key to the properties of the resulting polymer.

• In cellulose, beta-glucose monomers link using 1;1,4-glycosidic bonds.
• This bond angle and direction lead to the straight and rigid structure of cellulose fibers.

Understanding monomer configuration helps explain why cellulose is so effective in its role in plant cells. It sheds light on the importance of molecular geometry in biological systems.