Methyl butyrate, also known under the systematic name methyl butanoate, is the methyl ester of butyric acid. As with most esters, it has a fruity odour in this case resembling apples or pineapples.

Pentyl butyrate, also known as pentyl butanoate or amyl butyrate, is an ester that is formed when pentanol is reacted with butyric acid, usually in the presence of sulfuric acid as a catalyst.

A colourless liquid water-soluble acid, C3H7COOH; r.d. 0.96; b.p. 163°C. It is a weak acid (K a = 1.5 × 10−5 mol dm−3 at 25°C) with a rancid odour. Its esters are present in butter and in human perspiration. The acid is used to make esters for flavourings and perfumery.