<unk>  reacts as a typical carboxylic acid: it can form amide, ester, anhydride, and chloride derivatives. The latter, butyryl chloride, is commonly used as the intermediate to obtain the others.
Butyric acid
Choline
Phenylacetic acid
Inositol
Gamma-Amino-beta-hydroxybutyric acid
Gluten
Palate
Keto acid