Chemically, carbohydrates are defined as optically active polyhydroxy aldehydes or ketones, or compounds that produce such units on hydrolysis. Sugars like sucrose and lactose, common carbohydrates, are also referred to as saccharides, deriving from the Greek word “sakcharon,” meaning sugar.

Acetic acid fits the general formula C₂(H₂O)₂ but is not a carbohydrate because carbohydrates are defined as optically active polyhydroxy aldehydes or ketones, and acetic acid lacks these specific functional groups.

The general formula for carbohydrates is Cₓ(H₂O)ᵧ. The term “carbohydrate” originates from the idea that these compounds are hydrates of carbon, as seen in the molecular formula of glucose (C₆H₁₂O₆).

Diazonium salts are versatile intermediates for introducing substituents like -F, -Cl, -Br, -I, -CN, -OH, -NO₂ into the aromatic ring through electrophilic substitution reactions, enabling the synthesis of substituted aromatic compounds that may not be directly prepared by other methods.

Coupling reactions involve the reaction of benzene diazonium chloride with phenol or aniline, leading to the formation of azo products like p-hydroxyazobenzene or p-aminoazobenzene. These reactions are examples of electrophilic substitution.