Organic Chemistry - Alcohols

Alcohols are a homologous series containing the hydroxyl functional group ($-OH$) bonded to a saturated carbon atom.

The general formula for aliphatic alcohols is $C_nH_{2n+1}OH$.

Alcohols are classified as primary ($1^\circ$), secondary ($2^\circ$), or tertiary ($3^\circ$) based on the number of carbon atoms attached to the carbon bearing the $-OH$ group.

Ethanol is manufactured by two main methods: the fermentation of glucose (using yeast at $37^\circ C$ in anaerobic conditions) and the catalytic hydration of ethene ($C_2H_4$) using $H_3PO_4$ catalyst at $300^\circ C$ and $60$ atm pressure.

Primary alcohols can be oxidized to aldehydes ($RCHO$) and further to carboxylic acids ($RCOOH$) using acidified potassium dichromate(VI) ($K_2Cr_2O_7/H^+$). The color change observed is from orange ($Cr_2O_7^{2-}$) to green ($Cr^{3+}$).

Secondary alcohols are oxidized to ketones ($RCOR$) using acidified $K_2Cr_2O_7$, whereas tertiary alcohols are resistant to oxidation under these conditions.

Elimination of water (dehydration) from alcohols using a catalyst like concentrated $H_2SO_4$ or hot $Al_2O_3$ yields alkenes.

Esterification occurs when an alcohol reacts with a carboxylic acid in the presence of an acid catalyst ($H_2SO_4$), forming an ester and water (e.g., $CH_3CH_2OH + CH_3COOH \rightleftharpoons CH_3COOCH_2CH_3 + H_2O$).