Hydrolysis and alcoholysis of alkali metal aluminium hydrides

• Published in: Inorganica Chimica Acta Vol. 21; pp. 157 - 161
• Main Authors: Turova, N.Ya, Karpovskaya, M.I., Novoselova, A.V., Bakum, S.I.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1977
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(00)86253-2

The alcoholysis and hydrolysis of MAlH 4(M = Li, Na, K, Cs) has been studied in solutions in ether, tetrahydrofuran, and diglyme at 20°C. All the compounds studied react with primary and secondary alcohols in the stoichiometric ratio of 1:4 to yield MAl(OR) 4. Likewise goes the reaction of compounds MAlH 4 (M = Na, K, Cs) with water. In the case of tert-butyl alcohol, the reaction terminates after the addition of 3 mol of the alcohol to 1 mol of a complex hydride to give MAlH(OBu-tert) 3. Completion of the hydrolisis of LiAlH 4 occurs at the H 2O to LiAlH 4 ratio of 2.6 in solutions in tetrahydrofuran and of 7:1 in solutions in ether. Smooth gas evolution curves indicate a one-step course of both hydrolysis and alcoholysis with the formation of metal hydroxo- and alkoxoaluminates. The IR spectra and X-ray powder photographs show the products of partial solvolysis to be mixtures of metal aluminium hydrides and the final alcoholysis (hydrolysis) products. Evidence is presented against the existence of solids. metal alkoxoaluminium hydrides as individual compounds, except in the case of MAlH(OBu-tert) 3.