<P> A carboxylic acid / ˌkɑːrbɒkˈsɪlɪk / is an organic compound that contains a carboxyl group (C (= O) OH). The general formula of a carboxylic acid is R--COOH, with R referring to the rest of the (possibly quite large) molecule . Carboxylic acids occur widely and include the amino acids (which make up proteins) and acetic acid (which is part of vinegar and occurs in metabolism). </P> <P> Salts and esters of carboxylic acids are called carboxylates . When a carboxyl group is deprotonated, its conjugate base forms a carboxylate anion . Carboxylate ions are resonance - stabilized, and this increased stability makes carboxylic acids more acidic than alcohols . Carboxylic acids can be seen as reduced or alkylated forms of the Lewis acid carbon dioxide; under some circumstances they can be decarboxylated to yield carbon dioxide . </P> <P> Carboxylic acids are commonly identified using their trivial names, and usually have the suffix - ic acid . IUPAC - recommended names also exist; in this system, carboxylic acids have an - oic acid suffix . For example, butyric acid (C H CO H) is butanoic acid by IUPAC guidelines . The - oic acid nomenclature detail is based on the name of the previously - known chemical benzoic acid . For nomenclature of complex molecules containining a carboxylic acid, the carboxyl can be considered position one of the parent chain even if there are other substituents, for example, 3 - chloropropanoic acid . Alternately, it can be named as a "carboxy" or "carboxylic acid" substituent on another parent structure, for example, 2 - carboxyfuran . </P>

Potassium salts of long chain carbolic acids are known as