Definition
Alcohols are organic compounds in which one or more hydroxyl groups (–OH) are attached to a saturated carbon atom (sp³-hybridized) of an alkyl group.
General Formula
- For simple (monohydric) alcohols: CₙH₂ₙ₊₁OH
- Example: Ethanol (CH₃CH₂OH)
Classification of Alcohols
- Based on number of –OH groups
- Monohydric: One –OH group (e.g., methanol, ethanol).
- Dihydric: Two –OH groups (e.g., ethylene glycol).
- Trihydric: Three –OH groups (e.g., glycerol).
- Based on the type of carbon attached to –OH
- Primary alcohols (1°): –OH attached to a carbon bonded to only one alkyl group (e.g., ethanol).
- Secondary alcohols (2°): –OH attached to a carbon bonded to two alkyl groups (e.g., isopropanol).
- Tertiary alcohols (3°): –OH attached to a carbon bonded to three alkyl groups (e.g., tert-butanol).
Properties of Alcohols
- Physical: Colorless liquids/solids, soluble in water (small-chain alcohols), higher boiling points than hydrocarbons due to hydrogen bonding.
- Chemical:
- Show acidic nature (form alkoxides with sodium).
- Undergo oxidation (to aldehydes, ketones, or acids).
- Can be esterified with acids.
Uses of Alcohols
- Methanol: Solvent, antifreeze, fuel, raw material for formaldehyde.
- Ethanol: Alcoholic beverages, fuel (bioethanol), solvent, antiseptic.
- Glycerol: Used in cosmetics, medicines, and explosives (nitroglycerin).
In short: Alcohols are compounds with one or more –OH groups bonded to saturated carbons. They are widely used as solvents, fuels, disinfectants, and raw materials in industry.