Carbohydrates are the most common organic compounds on the planet.

• They are necessary for all forms of life because they serve as energy storage (glucose, starch, and glycogen), structural reinforcement (cellulose), and genetic information storage as components of nucleic acids (DNA and RNA).

• Monosaccharides are the monomers from which bigger carbohydrates are produced and have molecular formulae of CnH2nOn (3 # n # 8)

The suffix -ose is used to designate monosaccharides.

• Tri-, tetra-, penta-, hexa-, and other prefixes are used to denote three, four, five, and six carbon atoms, respectively.

An aldehyde carbohydrate is known as an aldose, and it is sometimes prefixed with the prefix aldo-

• The term Carbohydrates refers to polyhydroxylated aldehydes or ketones or compounds that produce polyhydroxylated aldehydes or ketones upon hydrolysis.

• Because monosaccharides typically include one or more chiral centers, stereochemistry is critical.

• A Fischer projection of a monosaccharide is used to display its structure and hence track stereochemistry.

• The monosaccharide is depicted in open-chain form in a Fischer projection, with the carbonyl carbon atom at the top of the molecule.

• Horizontal lines represent groups that project above the plane of the paper, while vertical lines show groups that project below the plane of the paper.

The carbon atoms of chiral centers are not identified in a Fischer projection.

• They are expected to be positioned at line intersections.

• When compared to glyceraldehyde stereochemistry, the overall stereochemistry of monosaccharides is characterized as d or l.

The point of reference in a monosaccharide is the chiral center furthest away from the carbonyl group.

• Because this is the next-to-last carbon atom in the chain (the last carbon atom of the chain in a normal carbohydrate has two!H atoms, therefore it is not a chiral center), it is referred to as the penultimate carbon atom.

A d-monosaccharide is a monosaccharide that has the same arrangement about its penultimate carbon as d-glyceraldehyde.

• In this scenario, the!OH group in the Fischer projection is on the right side of the carbon atom.

• An l-monosaccharide has the same structure around its penultimate carbon atom as l-glyceraldehyde, with the!OH substituent.

A cyclic hemiacetal structure is in equilibrium with the open-chain monosaccharides.

• The cyclic hemiacetal is highly preferred and consequently abundant at equilibrium.

• When a carbohydrate forms a six-membered hemiacetal ring, it is referred to as a pyranose, and when a carbohydrate forms a five-membered hemiacetal ring, it is referred to as a furanose.

• Cyclic monosaccharide structures are frequently drawn as Haworth projections, with the five-membered or six-membered cyclic hemiacetal drawn as the anomeric carbon atom is on the right, with the hemiacetal oxygen atom in the rear.

• For six-membered ring hemiacetals, a more precise chair conformation may be sketched, indicating which groups are axial and which are equatorial.

  • Mutarotation: refers to the change in specific rotation that accompanies the interconversion of a- and b-anomers in aqueous solution.

The glycoside's name is made up of the name of the alkyl or aryl group that is bound to the acetal oxygen atom, followed by the name of the monosaccharide in which the terminal -e has been substituted with -ide.

• A disaccharide is composed of two monosaccharide units connected by a glycosidic bond. Other terms for carbohydrates with a higher number of monosaccharides include trisaccharide, tetrasaccharide, oligosaccharide, and polysaccharide.

• Sucrose is a disaccharide composed of d-glucose and d-fructose linked by an a-1,2-glycosidic linkage.

Lactose is a disaccharide composed of d-galactose connected to d-glucose by a b-1,4-glycosidic bond, whereas maltose is composed of two molecules of d-glucose united by an a-1,4-glycosidic bond.

• The term glycoside refers to an acetal produced from a monosaccharide, and the glycosidic bond is the link between the anomeric carbon and the!OR group.

• Following the typical acetal production method, glycosidic linkages can be formed by reacting a saccharide with an alcohol in acid.

• When an amine, usually as part of a heterocyclic ring, makes a connection with the anomeric carbon, an N-glycoside is formed.

An alditol is a polyhydroxy molecule created by reducing a monosaccharide's carbonyl group to a hydroxyl group.

Starch may be divided into two parts known as amylose and amylopectin.

• Amylose is a linear polymer composed of up to 4000 d-glucopyranose units linked by a-1,4-glycosidic linkages.

• Amylopectin is a highly branched polymer of d-glucopyranose held together by a-1,4-glycosidic linkages and, at branch sites, a-1,6-glycosidic bonds.

• Glycogen, an animal's energy reserve carbohydrate, is a highly branched polymer of d-glucopyranose linked by a-1,4-glycosidic bonds and, at branch points, by a-1,6-glycosidic bonds.

• Cellulose, a plant's skeletal polysaccharide, is a linear polymer of d-glucopyranose united by b-1,4.

  • The ribbon-like shape of the individual chains, which fit together flawlessly through extensive hydrogen bonding to generate exceptionally strong structures, accounts for cellulose's strength.

• Rayon is created from cellulose that has been chemically changed and regenerated.