| abstract |
Alkoxides of transition metals, selected from among tetravalent Ti, tetravalent and pentavalent V, tetravalent Cr and tetravalent Zr, actinides and lanthanides, are reduced to corresponding alkoxides of lower valency by reacting such higher valency metal alkoxides, in liquid phase, with vapors of metals of the alkaline earth group, the III group and the IV group metals and magnesium. Very efficient polymerization catalysts for the polymerization of unsaturated compounds are thus obtained. |