Methanolysis and hydrolysis of magnesium aluminium bimetallic alkoxides

Abstract

In view of the successful synthesis of spinel, MgAl₂O₄, by the hydrolysis of magnesium bis-tetraalkoxyaluminate, [[Mg{Al(OR)₄}₂], the composition of hydrolysis products of Mg{Al(OPrⁱ)₄₂under different experimental conditions has been investigated during the present investigation. It has been found that the initial hydroxy products formed by the replacement of isotopoxy groups tend to undergo condensation (dehydration as well as dealcoholation) reactions to give oxide alkoxide products of varying compositions. Since the corresponding methanolysis reactions of Mg{Al(OPrⁱ)₄}₂ should not involve condensation tendencies similar to those in hydrolysis reactions, a detailed study of the methanolysis reactions of Mg{Al(OPrⁱ)₄}₂ has been carried out in an effort to throw light on the mechanism of such reactions. In the methanolysis reaction, the terminal isopropoxy groups appear to be replaced first leading to formation of transient insoluble products, which tend to become soluble by the interchange of bridging isopropoxy groups by the terminal methoxy groups. The products obtained in the course of hydrolysis and methanolysis have been analysed and a mechanism for the reaction processes has been proposed.