Recovery of a Lewis acid from a reaction mixture, prepared by hydrocyanation of an olefinically unsaturated compound to form a nitrile, comprises phase separation and distillation

摘要

A process for the recovery of a Lewis acid from a reaction mixture prepared by hydrocyanation of an olefinically unsaturated compound to form a nitrile that under certain conditions of quantities, pressure and temperature exhibit a miscibility gap with water, in the presence of a catalyst system containing a Lewis acid and a complex compound comprises phase separation and distillation. A process for the recovery of a Lewis acid from a reaction mixture (I), prepared by hydrocyanation of an olefinically unsaturated compound to form a nitrile that under certain conditions of quantities, pressure and temperature exhibit a miscibility gap with water, in the presence of a catalyst system containing a Lewis acid and a complex compound comprising a phosphorous containing ligand and a central atom is characterized in that: (a) the complex compound is separated from the mixture (I) to yield a mixture (II); (b) mixing of the mixture (II) with water under pressure and temperature to form a phase (III) that contains a higher water content than the nitrile and a phase (IV) having a higher nitrile content than water whereby the phase (III) has a higher content of Lewis acid than phase (IV); (c) mixing of the phase (III) with a liquid diluent (V) that does not form an azeotrope with water and whose b.pt. is higher than that of water or under certain conditions of pressure forms an azeotrope or a heteroazeotrope with water; (d) distillation of the mixture of (III) and (V) to yield a mixture (VI) having a higher water content than the diluent (V) and a mixture (VII) having a higher diluent (V) content than water whereby the mixture (VII) has a higher Lewis acid content than the mixture (VI) and; (e) addition of the mixture (VII) to a hydrocyanation of an olefinically unsaturated compound to form a nitrile that under certain conditions of quantities, pressure and temperature exhibit a miscibility gap with water, in the presence of a catalyst system containing a Lewis acid and a complex compound comprising a phosphorous containing ligand and a central atom.