Abstract: In a process for the hydrogenation of nitrobenzene with hydrogen to hydrazobenzene at temperatures ranging from 40.degree. to 110.degree. C. in the presence of a precious metal catalyst, an aqueous alkaline solution and an organic solvent, the reaction mixture being maintained in turbulent motion, the improvement wherein said nitrobenzene is o-, m- or p-chloronitrobenzene, the reaction is carried out in an organic solvent in which the dichlorohydrazobenzene being formed is readily soluble when warm and difficultly soluble when cold, and that the precious metal catalyst is used in such amount that the weight ratio of chloronitrobenzene used to precious metal catalyst is in the range 1:0.00005-less than 0.0002.

Abstract: A compound of tetravalent vanadium of the general formula ##STR1## wherein M represents a metal of the fourth group of the Periodic Table of the Elements and R represents and alkyl, cycloalkyl or aryl moiety of 1 to 20 carbon atoms and a process for its preparation. Also disclosed is the use of such vanadium compound as a catalyst for homopolymerization, copolymerization or terpolymerization of various monomers including olefins and vinyl monomers.