Patent ID: 8933277
Filing Date: 2015-01-13
Classification: C07C

Abstract:
1. A process for recovering components from a low boiler mixture which is obtained in distillation of hydrogenation effluents from preparation of polymethylols, wherein the low boiler mixture is prepared by a) condensing an alkanal in an aldol reaction with formaldehyde in the presence of a tertiary amine as a catalyst to give a reaction mixture comprising a methylolalkanal of the formula (II) b) distillatively separating the reaction mixture into a bottom discharge comprising predominately the methylolalkanal of the formula (II), c) hydrogenating the bottom discharge, and d) distilling the hydrogenated bottom discharge and removing the low boiler mixture and wherein the process for recovering components from the low boiler mixture comprises e) distilling the low boiler mixture comprising a tertiary amine, water, methanol, polymethylol of the formula (I) the methylolalkanal of the formula (II) an alcohol of the formula (III) and an alkanal with a methylene group in the a position to the carbonyl group, and in which each R is independently a further methylol group or an alkyl group having 1 to 22 carbon atoms or an aryl or aralkyl group having 6 to 22 carbon atoms, in a multistage distillation by separating the low boiler mixture in a first distillation stage into a higher-boiling, predominantly water-rich fraction and into a lower-boiling aqueous organic fraction comprising the tertiary amine, and f) separating the aqueous organic fraction from the first distillation stage in a second distillation stage into a predominantly amine-containing fraction and a further amine-depleted fraction, wherein the tertiary amine is trimethylamine or triethylamine, and the bottom temperature in the second distillation stage is at least 110° C.