 Methyl butanoate

Methyl butanoate is the ester $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}(=\mathrm{O})\mathrm{OC}{\mathrm{H}}_3$. The four-carbon butanoyl group and one-carbon methyl group occupy different sides of the ester linkage.

Hydrolysis yields butanoic acid or butanoate together with methanol, depending on conditions. The carbonyl carbon remains part of the acid-derived fragment.