Cellulose is a naturally occurring complex linear biopolymer consisting of carbon, hydrogen, and oxygen atoms with a general formula of [C6H10O5]n. The structure of this compound is constructed by hundreds to thousands of d-glucose monosaccharide units, linked together with a β-(1,4) linkage to form a chain. This macromolecule is abundant in nature and is mainly found in plant cell walls, algae, and some bacteria and other microorganisms.
It has no taste, no odor, and a chiral compound. It was discovered by Anselme Payen in the year 1838 who was a French Chemist. This complex biopolymer is completely biodegradable in nature.
Structure of Cellulose
This biopolymer is generally made by the polymerization of d-glucose monomers. The d-glucose units are attached to each other via beta 1-4 glycosidic bonds known as beta-acetal connection. The beta-D-glucose units are monomers in this polymeric molecule and the beta-acetal links create a connection of the number 1 carbon atom of one glucose to the number 4 carbon atom of the next glucose molecule to the formation of this compound.
The number one carbon atom in a glucose molecule locates at the center of the functional acetal group linked to two ether oxygen atoms. The d-glucose molecules have the ability to rotate 180° to each other in order to form the beta 1,4 glycosidic bonds.
It shows the reversed orientation in which the hydroxyl group of the number one carbon atom is directed above the plane of the glucose ring. Every alternate glucose molecule in this macromolecule is inverted for the presence of beta 1-4 glycosidic bonds.
It is found that the hydroxyl group of carbon number 1 is directed upwards whereas carbon number 4 is directed downward. As a result, every alternate glucose molecule in cellulose shows a reverse orientation shape.
This polymeric molecule is completely linear and unbranched. This molecule does not form any coiling, helix formation, or branching shape rather than they are arranged in parallel shape to each other. The chain of this molecule is attached to each other due to the presence of hydrogen bonds among hydrogen atoms and hydroxyl groups. This is the main reason for the presence of great strength in this molecule.
This macromolecule is found in plant cell walls in the form of cellulose microfibrils. These are attached to each other and form a strong matrix.
Physical properties
The chemical formula of this compound is [C6H10O5]n. The molecular weight/molar mass of this compound is generally 162.1406 g/mol. The density of this naturally occurring compound is 1.5 g/cm³. It is a white, crystalline, tasteless, odorless, and chiral compound. The melting point of this important compound ranges from 260–270 °C.
Chemical properties
The structure of this molecule is broken down into glucose monomers by treatment with concentrated mineral acids at higher temperatures. This compound has a crystalline shape. It can be formed an amorphous transition at 320 degrees and a pressure of 25 megapascals.
This molecule is insoluble in water but soluble in organic solvents. The alternate shape of the glucose monomer in this macromolecule is the main reason for the presence of higher tensile strength and stiffness. The thermal ability of this polymer is great and it is a biodegradable molecule.
Functions
It is regarded as the backbone of plants and algae. The cell wall of plants and wood are supported by cellulosic fibers distributed in a lignin matrix. Here, cellulose acts as reinforcing bars and the lignin acts like concrete.
Cotton contains over 90% whereas wood consists of 40-50% cellulose. There exist various types of bacteria which secrete this compound for the production of biofilms. These films help to organize them and form colonies.
Animals are unable to produce this molecule. Humans cannot digest this molecule in the absence of a hydrolytic cellulase enzyme in their intestines because this enzyme breaks the glycosidic linkage among the compound. On the other hand, Ruminants have cellulase enzymes for the digestion of this compound.
Derivatives
There are various cellulosic derivatives exist as important materials which are biodegradable and renewable resources. They are regarded as non-toxic and non-allergenic. The name of important derivatives is cellulose acetate, nitrocellulose, celluloid, cellophane, rayon, carboxymethyl cellulose, etc.
Applications
It is used as a good fiber supplement in our diet as well as an additive in several food items. It is used for the production of rayon and various explosives. The cellulose from natural plants is used very much in the textile industry directly or processed to make various products. Microcrystalline cellulose (MCC) can be used as filler in drugs and as food thickeners, emulsifiers, and stabilizers.
This important macromolecule is used for the production of filter media, sponges, glues, eye drops, laxatives, and films. Bio-fuel can be prepared by this compound. The paper, insulation paper, stationary phase in chromatography, and paperboard are made of cellulosic molecules.
Frequently Asked Questions (FAQ’s)
- What is a cellulose molecule?
It is a naturally occurring complex linear biopolymer consisting of carbon, hydrogen, and oxygen atoms with a general formula of [C6H10O5]n. The structure of this compound is constructed by hundreds to thousands of d-glucose monosaccharide units, linked together with a β-(1,4) linkage to form a chain.
2. What is the structure of cellulose?
The d-glucose units of glucose are attached to each other via beta 1-4 glycosidic bonds known as beta-acetal connection in this compound. The beta-D-glucose units are monomers in this polymeric molecule and the beta-acetal links create a connection of the number 1 carbon atom of one glucose to the number 4 carbon atom of the next glucose molecule to the formation of this compound.
3. Why cellulose cannot be digested in the human body?
Humans cannot digest this molecule in the absence of a hydrolytic cellulase enzyme in their intestines because this enzyme breaks the glycosidic linkage among the cellulose. On the other hand, Ruminants have cellulase enzymes for the digestion of this polymer.
4. What is cellulose used for?
It is used very much in the textile industry directly or processed to make various products. Microcrystalline types of this compound can be used as fillers in drugs and as food thickeners, emulsifiers, and stabilizers.
5. What are the derivatives of cellulose?
The important derivatives are cellulose acetate, nitrocellulose, celluloid, cellophane, rayon, carboxymethyl cellulose, hydroxypropyl methylcellulose, ethyl hydroxyethyl cellulose, etc.
References
- Marchessault, R. H., & Sundararajan, P. R. (1983). Cellulose. In The polysaccharides (pp. 11-95). Academic Press.
- French, A. D., Bertoniere, N. R., Battista, O. A., Cuculo, J. A., & Gray, D. G. (2000). Cellulose. Kirk‐Othmer Encyclopedia of Chemical Technology.
