Alcohols and phenols react with carboxylic acids, acid chlorides and acid anhydrides to form esters.
R-O-H + R' - COOH -----H+-----> ROCOR' + H2O
Ethanol Acetic acid Ethyl acetate(Ester)
C2-OH + CH3-COOH -----H2SO4----------> C2H5O COCH3 + H2O
Ar-OH + R'-COOH ------------------> ArOCOR' + H2O
Ar-OH/ R-OH + (R'CO)2 ---------H+----------> Ar/ ROCOR' + R'COOH
Ease of esterification of alcohol is in the order primary> secondary> tertiary .
The reaction with carboxylic acid and acid anhydride is carried out in presence of small amount of concentrated sulphuric acid. The reaction with carboxylic acid is reversible, and therefore, water is removed as soon as it is formed. The Reaction With Acid Chloride Is Carried Out In Presence Of A Base (Pyridine) so as to remove HCl. It also shifts the equilibrium to right hand side. The introduction of acetyl (CH3CO-) group in alcohols or phenols is known as acetylation. Acetylation of salicylic acid (2-hydroxy benzoic acid) produces aspirin which possesses analgesic, anti-inflammatory and antipyretic properties.
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