GB692882A - Improvements in the recovery of adiponitrile and in apparatus therefor - Google Patents

Abstract

Adiponitrile is recovered from the pasty mixture obtained by the reaction of a 1 : 4-dihalogenobutane with excess alkali or alkaline earth metal cyanide by introducing the pasty mixture under reduced pressure into an apparatus fitted with stirring blades or a screw conveyer and heated externally and/or by internally disposed heating plates to temperatures exceeding the boiling-point of the adiponitrile so that the latter distils over and a dry residue of salts remains. Three forms of apparatus are illustrated (not shown), wherein is treated the pasty mixture obtained by reacting 1 : 4-dichlorobutane with excess sodium cyanide and containing adiponitrile, sodium chloride and the excess sodium cyanide. In each case, the pasty mixture is continuously propelled into the reactor where it is heated under reduced pressure at 260 DEG C. whereupon the nitrile distils off and a dry residue of salts is continuously removed. One reactor is externally heated and has a vertically mounted spiral blade stirrer and a bottom removal point for withdrawal of the salts; another externally heated reactor is in the form of a horizontal tube with a screw conveyer along its length; the third reactor has several steam-heated plates arranged one above the other, the pasty mixture being fed from the top and swept over the plates by means of stirring blades and holes are provided in the plates at different positions to allow the residual salts to fall to a bottom removal point.ALSO:Adiponitrile is recovered from the pasty mixture obtained by reacting a 1:4-dihalogene butane with excess of an alkali or alkaline earth metal cyanide by introducing the pasty mixture under reduced pressure into a vessel fitted with stirring blades or a screw conveyer and heated externally and/or by internally disposed heating plates to temperatures exceeding the boiling point of the adiponitrile so that the latter distils over and a dry residue remains. The process described is continuous and provision is made for automatic removal of the dry salts from the reactor. Three forms of suitable apparatus are illustrated (not shown).