How to identify carboxylic acid and anhydride
Acid chloride (anhydride) and alcohol;
carboxylic acid and alcohol in the Lewis acid catalyzed reaction ester
carboxylic acid and acetic anhydride reaction dehydration to produce acid anhydride;
and phosphorus tribromide reaction to form bromide;
Carboxylic acid and chlorinated sulfuryl chloride or oxalyl chloride reaction can be converted to acid chloride;
