From acyl chloride and anhydrides

(a) Acyl chlorides, on hydrolysis with plain water, give carboxylic acids directly -- and this method works equally well for both aliphatic and aromatic acids: R-COCl + H2O gives R-COOH + HCl. (b) Anhydrides, likewise, give carboxylic acids on hydrolysis with water: an anhydride (R-CO)2O + H2O gives 2 R-COOH. The section also shows how an acyl chloride and a sodium carboxylate salt are each obtained SEPARATELY, straight from the parent acid -- the acid with thionyl chloride gives the acyl chloride (R-COOH + SOCl2 gives R-COCl), while the acid with sodium hydroxide gives the sodium salt (R-COOH + NaOH gives R-COONa) -- and that reacting THESE TWO products together (sodium carboxylate + acyl chloride) actually gives a …