Isophthalic acid

Isophthalic acid, or benzene-1,3-dicarboxylic acid, is an aromatic dicarboxylic acid, with formula C6H4(COOH)2.

It is an isomer of phthalic acid and terephthalic acid.

Isophthalic acid can be obtained by oxidizing meta-xylene with chromic acid, or by fusing potassium meta-sulphobenzoate, or meta-brombenzoate with potassium formate (terephthalic acid is also formed in the last case). It melts above 300°. The barium salt (6H2O) is very soluble (a distinction between phthalic and terephthalic acids). Uvitic acid, 5-methylisophthalic acid, is obtained by oxidizing mesitylene or by condensing pyroracemic acid with baryta water.