GB1204301A - Production of esters of terephthalic and isophthalic acids - Google Patents

Abstract

1,204,301. Production of bis (2-hydroxyalkyl) phthalates. CELANESE CORP. 2 Jan., 1969 [2 Jan., 1968; 13 May, 1968], No. 267/69. Heading C2C. A process for the production of a bis (2-hydroxy alkyl) terephthalate and/or isophthalate comprises suspending terephthalic acid and/or isophthalic acid in an inert liquid aromatic medium, e.g. C 8 alkylbenzenes, which is a solvent for the diester(s) but not for the acid(s), catalytically reacting in a reaction zone the suspended acid(s) with a vicinal alkylene epoxide at a temperature of from 100‹ to 200‹ C., so as to form said diester(s), passing the reaction zone contents to a separation zone and removing therefrom a liquid stream consisting essentially of said aromatic medium and said diester(s), the reaction zone contents, separation zone and said liquid stream being maintained at a temperature which is at least 100‹ C. and which is high enough to keep said diester(s) in liquid form, passing said liquid stream to an extraction zone where it is intimately contacted with water and a water phase and an aromatic phase are formed, the amount and temperature of the water being such that said water phase is at a temperature of at least 60‹ C. and being an amount of water which at the temperature of said water phase would dissolve the amount of diester(s) entering said extraction zone, withdrawing said water phase from said extraction zone and passing it to a crystallization zone and crystallizing the diester(s) therefrom as product. Prior to entry to the crystallization zone the water phase containing the diester(s) may be purified by treatment with activated carbon or by treating with a bisulphite or sulphite or by hydrogenation in the presence of a hydrogenation catalyst. Suitable catalysts for the reaction of the acid with the alkylene oxide are tertiary amines and quaternary ammonium compounds. The production of bis (2-hydroxyethyl) terephthalate is described.