Carboxylic acid Carboxylic acid A carboxylic acid 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). 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, along with
Syringic acid in vinegar. Syringic acid can be enzymatically polymerised. Laccase and peroxidase induced the polymerization of syringic acid to give a poly(1,4-phenylene oxide) bearing a carboxylic acid at one end and a phenolic hydroxyl group at the other. Syringic acid Syringic acid is a naturally occurring "O"-methylated trihydroxybenzoic acid, a type of chemical compound. Syringic acid can be found in "Ardisia elliptica". Syringic acid can be prepared by selectively hydrolyzing (demethylating) eudesmic acid with 20% sulfuric acid. Syringic acid can be found in the açaí palm ("Euterpe oleracea") and its oil (1,073 ± 62 mg/kg). It is also present in wine.