GB859468A - A process for the production of borohydrides - Google Patents

Abstract

In preparing borohydrides, the hydride of Al, Mg, Ca, Sr, Ba, Li, Na, K, Rb, or Cs is reacted with a metaborate, or a metal oxideboron oxide mixture in 1:1 molar ratio of a metal of the above series, which is not further to the left in the series than the hydride metal, at above 100 DEG C. but below the melting point of the mixture, whereby the borohydride of the metal in the metaborate or in the oxide mixture, and the oxide of the hydride metal are formed. Alternatively, a metal aluminium hydride may be used in place of aluminium hydride, or the metal hydride may be produced in situ, e.g. from metal, or carbide, and hydrogen. The hydride may be prepared as described in Specification 792,017. By this method, Li, Na, Ca, Sr, or Ba borohydrides may be prepared from CaH2, and the initial reactants may be ground mixed, and briquetted. Air and moisture should be excluded from the reaction, and an acid anhydride, e.g. SiO2, may be added to take up the metal oxide formed. The product may be extracted with water, with, or without, recrystallization from methanol, or with methanol, liquid ammonia, or isopropylamine. In Examples:- (1), (2), NaBO2 or KBO2 is briquetted with CaH2 and heated in an autoclave under hydrogen pressure; (3) NaBO2 is briquetted with CaC2 and heated under H2 pressure; (4) NaBO2 is mixed with CaCl2 and Na sand and the mixture heated in an autoclave under H2 pressure.