Naming Esters

Esters have the functional group -COO- and the general formula RCOOR'. They are made from a carboxylic acid and an alcohol, and the name is built from both parents.An ester is named as an alkyl alkanoate. The first word comes from the alcohol (methyl, ethyl, propyl and so on). The second word comes from the carboxylic acid, with the ending -oic acid changed to -oate.ethanoic acid + methanol → methyl ethanoate, CH₃COOCH₃Take care: the formula is usually written with the acid part first (RCOO) and the alcohol part last (R'), but the name puts the alcohol part first. The carbon of the C=O group always belongs to the acid part.Worked example: name CH₃CH₂COOCH₃. Split the formula after the COO. The acid part, CH₃CH₂COO, has 3 carbons, so it is propanoate. The group on the other oxygen, CH₃, came from methanol, so it is methyl. The name is methyl propanoate.More examples: HCOOCH₂CH₃ is ethyl methanoate, and C₆H₅COOCH₃ (made from benzoic acid) is methyl benzoate.An ester and a carboxylic acid with the same number of carbon atoms share a molecular formula, so they are functional group isomers. For example, C₃H₆O₂ can be propanoic acid, methyl ethanoate or ethyl methanoate.