Reactions with PCl5, PCl3 and SOCl2
The hydroxyl group of carboxylic acids, behaves like that of alcohols
and is easily replaced by chlorine atom on treating with PCl5, PCl3 or
SOCl2 Thionyl chloride (SOCl2) is preferred because the other two
products are gaseous and escape the reaction mixture making the
purification of the products easier 4 Reaction with ammonia
Carboxylic acids react with ammonia to give ammonium salt which
on further heating at high temperature give amides