Abstract: The invention involves spherical particles of magnesium alkoxide and a process for their preparation. Specifically, spherical magnesium alkoxide is produced by spray drying of an alcoholic solution of the corresponding carboxylated magnesium alkoxide and subsequent drying and decarboxylation, characterized in that the solution is sprayed via a two-material nozzle with inner atomization, which is operated in the part-load range at 10 to 30% of its capacity, into an inert accompanying gas which is under a pressure of 1.0 to 1.2 bar, has been preheated to 100.degree.-140.degree. C. and is fed cocurrently, after which the resulting finely divided carboxylated magnesium alkoxide is dried and is decarboxylated. The magnesium alkoxide is used for the preparation of a catalyst for the polymerization of .alpha.-olefins.

Abstract: Disclosed are very pure zirconium and hafnium orthoesters and a method for their preparation. In this method the reaction between the halides of these metals and the alcohols is performed in the presence of hydrocarbons or chlorinated hydrocarbons, and the alcohol is not use in excess. The obtained orthoesters are in very pure form and not as addition products with alcohol. They can be isolated as solids.