ACID ANHYDRIDE + ALCOHOL => ESTER + CARBOXYLIC ACID.
The reaction is vigorous at room temperature and requires to be controlled by cooling.
For example: CH3COOCOCH3 + CH3CH2CH2CH2OH => CH3COOCH2CH2CH2CH3 + CH3COOH
In this reaction, ethanoic anhydride and butan-1-ol form the ester butyl ethanoate and ethanoic acid.