GB714385A - Purification of acrylonitrile - Google Patents

Abstract

Monomeric acrylonitrile containing as impurities minor amounts of hydrogen cyanide as such or as lactonitrile is purified by treating with from 0.0001-0.5 per cent by weight of an alkali metal or alkaline earth metal oxide, hydroxide, carbonate or cyanide in solution or in solid form. The treatment may be effected with aqueous base, finely divided solid base or slurried or dispersed solid base in a non-reactive solvent for acrylonitrile such as a hydrocarbon at from room temperature up to the boiling point of the acrylonitrile. The hydrogen cyanide is converted into a material which is either precipitated or is absorbed on the basic material when the latter is used in solid form. The basic material is subsequently removed with the impurities by subjecting the treated mixture to distillation, filtration, decantation or centrifugation. In typical examples, a crude acrylonitrile containing 700 p.p.m. hydrogen cyanide and obtained by reacting acetylene with hydrogen cyanide and distilling the resulting product is agitated with (1) 0.125 per cent solid sodium hydroxide pellets and then filtered; (5) with 0.01 per cent sodium carbonate in water and the aqueous layer then removed; (6) with 0.001 per cent calcium hydroxide slurried in kerosene; or (7) 0.01 magnesium carbonate in benzene and the solvent layer then removed; in each case the hydrogen cyanide content is reduced to below 5 p.p.m. The use of the basic potassium compounds is also mentioned.