IMPROVED METHOD OF ISOLATION OF DIETHERS OF POLYTETRAMETHYLENE ETHERS Russian patent published in 2000 - IPC

FIELD: preparation of segmented copolymers with polyurethanes and polyethers. SUBSTANCE: diethers of polytetramethylene ethers are prepared by polymerization of tetrahydrofuran optionally with one or more substituted tetrahydrofuran or alkylenoxide in reactor using solid acid catalyst and carboxylic acid with carboxylic acid anhydride as molecular weight regulating agents. Isolation process comprises (a) isolation of product containing diethers of polytetramethylene ethers, unreacted tetrahyrofuran, carboxylic acid with carboxylic acid anhydride, (b) instantaneous evaporation of bulk of unreacted tetrahydrofuran from solution of diethers at reduced pressure and (c) distillation-evaporation of remaining tetrahydrofuran of carboxylic acid and carboxylic acid anhydride using overheated tetrahydrofuran. Steam distillation of high-melting agents from stream of product when using tetrahydrofuran eliminates problems associated with high-temperature distillation used in well known method more particularly gel formation in synthesis process. EFFECT: more efficient isolation method. 2 cl, 1 dwg, 1 ex