Verfahren zur Herstellung von Polyalkoholen

摘要

The invention relates to a method for producing polymethylol compounds of formula (I), in which R represents a further methylol group or an alkyl group with between 1 and 22 C atoms or an aryl or alkyl aryl group with between 6 and 22 C atoms, by condensating aldehydes with between 2 and 24 C atoms with formaldehyde, using tertiary amines as catalysts, with a view to obtaining compounds of formula (II), in which R has the meaning assigned to it above. The invention further relates to a process for hydrogenating polymethylol compounds by condensation in stages. For this, a) in a first (reaction) stage, the aldehydes with 2 or more C atoms are reacted with 2 to 8 times the molar quantity of formaldehyde in the presence of a tertiary amine as catalyst; b) in a second (separation) stage, either the reaction mixture is separated into a distillation residue containing primarily the compounds of formula (II) and a destillation flow containing primarily the compounds of unreacted or partly reacted starting materials which is fed back to the first stage, or the reaction mixture of the first stage is separated into an aqueous and an organic phase by means of a phase separation device and the organic phase fed back to the first stage, and c) in a third (post-reaction distillation) stage, the distillation residue of the second stage or the aqueous phase obtained by phase separation during the second stage is subjected to a catalytic and/or heat treatment, the compound of formula (III) which has not been fully methylolized is transformed into the corresponding compound of formula (II) and into the corresponding methylene compound of formula (IV), in which R' represents hydrogen or has the meaning assigned above to R, the reaction mixture obtained in this way is distilled, and the distillation overhead product, which contains a compound of formula (IV) and unreacted formaldehyde, is fed back to the first stage. Thereafter, the still bottom of this distillation process, which essentially contains the compound of formula (II), is hydrogenated in the known manner so as to obtain the corresponding end product of formula (I).