Phthalide prodn. by hydrogenolysis of 3-chloro-phthalide - over noble metal catalyst with addn. of hexa:methylene:tetramine

摘要

The parent patent describes prodn. of phthalide (I) by hydrogenol = ysis of 3-chlorophthalide (II) at 50-250 degrees C in presence of a Group 8 noble metal catalyst. In this Addition hexamethylenetetramine (III) is added to the reaction mixt. Addn. of (III) eliminates the deleterious effects of metal ion impurities (esp. Fe) in crude (II) (these ions catalyse alkylation of the aromatic hydrocarbon solvent by (II)). (III) is used at 2-3.5 moles per mole metal cpd. Generally (II) contains 10-20 ppm metal as 50-100 mg. (III) per kg (II) is usually sufficient.