| 摘要 |
FIELD: chemistry.SUBSTANCE: present invention relates to a method of purifying raw polymethylol, which contains polymethylol of formula (I), as well as a hydroxy acid of formula (IV). According to the present method, raw polymethylol is obtained in a multistep process, wherein at step (a) alkanals react via aldol condensation with formaldehyde in the presence of tertiary amines as catalyst to form methylol alkanals of formula (II). Further, at step (b), the reaction mixture obtained at step (a) is divided by distillation into a still residue primarily containing compounds of formula (II) and a head stream containing low-boiling components. The stream coming from the bottom from step (b) is hydrogenated at step (c). The stream coming from step (c) is then distilled at step (d). Low-boiling components from the stream coming from step (c) are separated, and purification is carried out in a distillation column, wherein the bottom of the distillation column is connected to at least one evaporator with a short dwell time. In formulae,,R in each separate case independently denotes a methylol group or an alkyl group with 1-22 carbon atoms or an aryl group or an arylalkyl group with 6-22 carbon atoms.EFFECT: method reduces losses in output of polymethylol.12 cl, 5 ex |
