Methyl butanoate
= Methyl butanoate
<Methyl butanoate> is the <ester> $\mathrm{CH_3CH_2CH_2C(=O)OCH_3}$. 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.
<Organic Chemistry by John McMurry>[Chapter21, Carboxylic Acid Derivatives: ester identity and hydrolysis]{ref}