Regeneration of sodium borohydride from sodium metaborate, and isolation of intermediate compounds

摘要

A method for the regeneration of sodium borohydride from its hydrolysis product, sodium borate, is described. The dried borate salt was converted to a series of sodium tetraal-koxyborates prior to reaction with NaAlH_4 in refluxing diglyme to regenerate sodium borohydride. At room temperature in tetrahydrofuran, the same reactants formed the partial hydrides NaBH_3(OR) (R = C1-4 alkyl). Products were characterised by multinuclear ~1H, ~(13)C, ~(11)B and ~(27)Al NMR studies. The intermediate alkoxyborate products were confirmed by single crystal X-ray structural studies.