Sodium borohydride is one of the most common reducing agents. It can also be used to produce a variety of other borohydride salts via simple metathesis reactions. The biggest problem for those reactions is the limited choice of suitable solvents. Literature procedures in acetonitrile have been reported to only result heavily halide contaminated samples. Procedures in CH2Cl2 delivered similar poor results (halide contamination of 22.5%). So far only a co-solvent procedure utilizing liquid ammonia and CH2Cl2 at 200K delivered analytical pure heterocyclic borohydride salts, as well as a patent procedure which relies on a phase separation of a highly basic water layer and the organic borohydride layer. Clearly, not all organic borohydrides will survive those conditions. Here we report a different method for the preparation of heterocyclic borohydride salts, which takes advantage of the well-established coordination chemistry between NaBH4 and amines. The coordination complexes have completely different solvent characteristics than the parent compounds. This allowed us to run a much simpler metathesis in a single solvent at room temperature. The synthesis of the complex as well as results on some salts obtained by metathesis is presented.

Sodium borohydride amine complexes: A simple way to organic borohydride salts

251st National Meeting (2016)

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