Process for the selective hydrogenation of unsaturated compounds

Abstract

The selective hydrogenation of unsaturated compounds which carry reducible groups containing nitrogen succeeds in a homogeneous phase with the preservation of the reducible groups containing nitrogen, characterized in that a compound of the formula RuH.sub.2n L.sub.5-n is used as a catalyst, in which L signifies a phosphane or arsane and n signifies 1 or 2.

We claim: 
     
       1. A process for the hydrogenation of the C═C double bonds of a polymer consisting essentially of (i) 85 to 50% by weight of copolymerized units of conjugated dienes selected from the group consisting of .[.butadiene-1.3 and pentadiene-1.3,.]. .Iadd.butadiene-1.3, pentadiene-1.3, 2-methylbutadiene-1.3 and 2,3-dimethylbutadiene-1.3 .Iaddend.   (ii) 15 to 50% by weight of copolymerized units of unsaturated nitriles selected from the group consisting of acrylonitrile and methacrylonitrile, and   (iii) 0 to 10% by weight of copolymerized units of other copolymerizable monomer in a homogeneous phase up to a hydrogenation degree of more than 80% with preservation of the nitrile units,   which process comprises reacting the polymer with hydrogen to a degree of hydrogenation greater than 80% at a pressure from 1 to 350 bar and a temperature from 80° to 200° C. in a ketone solvent having 3 to 10 carbon atoms in the presence of 10 to 1,000 ppm catalyst, based on polymer, which is a compound of the formula   RuH.sub.2n L.sub.5-n     wherein L is of the formula ##STR2## wherein R 1 , R 2  and R 3  are the same or different and each is alkyl having 1 to 20 carbon atoms, cycloalkyl having 5 to 7 carbon atoms, aryl having 6 to 18 carbon atoms or aralkyl having 1 to 6 alkyl carbon atoms, and n is the integer 1 or 2.     
     
     
       2. A process according to claim 1, characterised in that triaryl phosphanes are used as ligands L. 
     
     
       3. A process according to claim 1, characterised in that triphenyl phosphane is used as ligand L.