1-oxo-1,3-dihydro-2-benzofuran-5-carboxylic acid, phthalide-5-carboxylic acid, 1-Oxo-1,3-dihydroisobenzofuran-5-carboxylic acid, 5-carbophthalide, 5-Carboxyphthalide, 1,3-Dihydro-1-oxoisobenzofuran-5-carboxylic acid, 1-oxo-phthalan-5-carboxylic acid, 5-Carboxyl-phthalide, 1-Oxo-phthalan-5-carbonsaeure, 1,3-dihydro-1-oxo-5-isobenzofurancarboxylic acid