Continuous process for the cyanoalkylation of compounds having one or more NH functions

Abstract

The invention relates to a continuous process, carried out in two steps, for the cyanoalkylation of compounds having one or more NH functions by reaction thereof with carbonyl compounds and hydrocyanic acid, in which the first step is carried out without pressure at a temperature which is below the boiling point of the reaction mixture.

We claim:  
     
         1 . A process for the cyanoalkylation of ammonia or organic compounds having one or more NH functions by reaction of said compounds with one mole of a carbonyl compound per NH function to be reacted and with one mole of hydrocyanic acid per NH function to be reacted, in a suitable solvent, which comprises carrying out the reaction in two sections, where the reaction in the first section is carried out to a degree of conversion of at least 60%, based on hydrocyanic acid, at a temperature T 1  which is below the boiling point of the reaction mixture, and the reaction in the second section is carried out to a degree of conversion of at least 90%, based on hydrocyanic acid, at a temperature T 2  which is below 150° C.  
     
     
         2 . A process as claimed in  claim 1 , wherein the reaction component containing NH functions is a compound of the formula I  
       R a —NH (3-   a )  ( I )  
       where R is a substituted or unsubstituted linear, branched or cyclic alkyl radical having 1 to 8 carbon atoms or aryl having 6 to 10 carbon atoms, a is one of the numbers 0, 1 and 2, and the compound of the formula I has a total of from 1 to 8 carbon atoms.  
     
     
         3 . A process as claimed in  claim 1 , wherein R in the formula I is linear alkyl having 1 to 4 carbon atoms, in particular 1 or 2 carbon atoms, or is phenyl, and the index a is 1 or 2 if R is alkyl or the number 1 if R is an aryl radical.  
     
     
         4 . A process as claimed in  claim 1 , wherein the carbonyl compound employed is an aldehyde of the formula II  
       R 2 −CHO  ( II )  
       where r 2  is hydrogen or a substituted or unsubstituted linear or branched alkyl radical having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, in particular 1 or 2 carbon atoms.  
     
     
         5 . A process as claimed in  claim 1 , wherein the carbonyl compound employed is formaldehyde, acetaldehyde or propionaldehyde.  
     
     
         6 . A process as claimed in  claim 1 , wherein the first reaction section is carried out in one or more cascaded, unpressurized reactors, and the second reaction section is carried out in one or more cascaded, pressurized reactors.  
     
     
         7 . A process as claimed in  claim 1 , wherein the reaction in the first reaction section is carried out to a degree of conversion of from 60 to 85%, and the reaction in the second reaction section is carried out to a degree of conversion of from 90 to 100%.  
     
     
         8 . A process as claimed in  claim 1 , wherein the second reaction section is carried out using tubular reactors which are advantageously provided with internals for reducing back-mixing, in particular with those which are designed in such a way that, in addition to preventing back-mixing, they also allow the reaction of inhomogeneous reaction mixtures.  
     
     
         9 . A process as claimed in  claim 1 , wherein the compound containing NH functions and the carbonyl compound are mixed in a mixing ratio such that from 0.2 to 2.0 mol of carbonyl compound are present in the reaction mixture per mole of NH function to be reacted, and the molar ratio between carbonyl compound and hydrocyanic acid in the reaction system is held in the range from 0.5 to 1.2.  
     
     
         10 . An a-cyanoalkylamine prepared by a process as claimed in  claim 1 .  
     
     
         11 . A method of performing continuing synthetic processes wherein an α-cyanoalkylamine prepared by a process as claimed in  claim 1  is applied as starting material.  
     
     
         12 . A method as claimed in  claim 11  wherein the first synthesis step of said continuing synthetic processe consists in hydrolysis of the cyano groups to give carboxamides or carboxylic acids.