A crystalline acid derived from benzene, with two carboxylic acid groups attached to the benzene ring.
- ‘Alkyd is produced by condensation reactions between polycarboxylic acids and polyhydric alcohols - often phthalic acid or anhydride and glycerol.’
- ‘A wide range of uses has been found for various phthalic acid esters, with the largest portion of these esters being used as plasticizing agents for polyvinyl chloride products.’
- ‘Capillaries were immersed in phthalic acid, which has an index of refraction that effectively eliminates optical refraction at the outer wall.’
Mid 19th century: phthalic, shortening of naphthalic (see naphthalene).