REACTIONS OF ALUMINUM ALKOXIDES WITH ACETYLACETONE, BENZOYLACETONE, AND ETHYL ACETOACETATE

Abstract

The observed stability of stable bridge structure, [Formula: see text] in aluminum alkoxides has been explained on the powerful tendency of aluminum to attain co-ordination number 4. This would predict the monomeric nature of the derivatives of the type, (OR)2Al(lig), where ligand (lig) is a diketone like acetylacetone (acac), benzoylacetone (bzac), or ketoester like ethyl acetoacetate (etac). This has been confirmed by actual synthesis of these compounds by reactions between aluminum alkoxides (ethoxide and isopropoxide) and acetylacetone, benzoylacetone, and ethyl acetoacetate in equimolecular ratios. These and also (OR)Al(lig)2 as well as Al(lig)3 have been shown to be monomeric in boiling benzene. The volatility of the derivatives was found in the order [(OPri)3Al]2 > (OPri)2Al(acac) > (OPri)Al(acac)2. This leads to the conclusion that chelation lowers the volatility and the direct relationship between volatility and molecular complexity, observed in the case of simple alkoxides, is not applicable in these derivatives. Further mixed derivatives of the type Al(acac)(etac)2 and Al(etac)(acac)2 have also been synthesized during the course of the above work.