Patent ID: 8975440
Filing Date: 2015-03-10
Classification: C07C

Abstract:
1. A process for preparing a carboxamide from a carbonyl compound and hydrogen cyanide, comprising: A) reacting a carbonyl compound with hydrogen cyanide to prepare a hydroxycarbonitrile in a first reaction mixture; B) hydrolyzing the hydroxycarbonitrile obtained in A) in the presence of an ionizable lithium compound and a catalyst comprising manganese dioxide to prepare a second reaction mixture, wherein a molar excess of carbonyl compound in relation to the hydrogen cyanide is present in the reacting A), wherein the first reaction mixture obtained in A) is not purified by distillation before the hydrolyzing B) is performed, wherein the second reaction mixture obtained after B) is purified by a two-stage distillation wherein a resulting carboxamide and water are separated from a third mixture which comprises a recovered carbonyl compound and at least one selected from the group consisting of the hydroxycarbonitrile and the hydrogen cyanide, and the water is separated from the resulting carboxamide in a further distillation, wherein a composition which comprises the carbonyl compound reacted in A) is introduced via a reflux into a still employed to separate the water and the hydrogen cyanide, wherein the composition introduced into the reflux has a lower proportion of HCN than a second composition withdrawn via the top of the still.