MANUFACTURE OF 3-HYDROXYPROPIONITRILE

摘要

A process for the production of 3-hydroxypropionitrile comprises (a) reacti ng acrylonitrile with water in a molar ratio of about 1:0.5 to about 1:20 in th e presence of a weak base under specific temperature and pressure conditions until a conversion in the range of about 40% to about 80% has been achieved in order to obtain a two- phase organic-aqueous mixture, the organic phase of which consists mainly of bis(cyanoethyl) ether and 3-hydroxypropionitrile as well as a relatively small amount of unreacted acrylonitrile, and the aqueous phase of which consists mainly of an aqueous solution of the weak base; (b) after cooling the mixture obtained in (a) separating off its aqueous phase; (c) distilling off the acrylonitrile from the organic phase remaining after (b) in order to obtain a mixture consisting mainly of bis(cyanoethyl) ether and 3- hydroxypropionitrile; (d) subjecting the mixture obtained in (c) to a pyrolysis carried out under specific temperature and pressure conditions in the presence of a basic catalyst selected from the group consisting of calcium, magnesium, strontium, titanium, iron and zinc oxides, alkali metal acetates, alkali metal formates, alkali metal and barium carbonates, alkali metal bicarbonates, calcium and copper hydroxides, di- and trisodium phosphates, sodium fluoride, sodium silicate and high boiling trialkylamines in order to obtain a mixture consisting mainly of 3-hydroxypropionitrile and acrylonitrile; and (e) isolating the desired 3-hydroxypropionitrile by fractional distillation from the mixture obtained in (d). Such a process which has recyclization of the basic aqueous phase as well as of the acrylonitrile which is distilled off represents a preferred embodiment. A further aspect o f the present invention consists in that, after the about 40% to 80% conversion has been achieved in process step (a), the weak base is neutralized by the addition of a weak aci d in order to obtain also in this case a two-phase organic-aqueous mixture, which instead of the original weak base contains base formed, inter alia, by the neutralization; this base represents the basic catalyst already used in the later process step (d), so that a special addition of a basic catalyst for process step (d) is avoided. The thus-produced 3- hydroxypropionitrile is an important intermediate in a process for the manufacture of panthenol, which, in turn, especially in the form of its d(+) isomer, is a valuable agent for the treatment of dermatoses, burns and infectious ulcers as well as a valuable additive in shampoos and other cosmetics.