NaBH3CN

Sodium cyanoborohydride, often abbreviated NaBH₃CN, is a white to slightly yellow crystalline solid that is soluble in water, alcohols and dichloromethane. It has the empirical formula NaBH₃CN. It is an important reducing agent in organic synthesis, especially for reductive amination reactions where it provides selective reduction of imines or iminium ions while remaining largely inert toward aldehydes, ketones and other functional groups under mild conditions. The reagent was first reported by R. G. Braham in the 1950s and has become a common alternative to sodium borohydride for applications that require a milder reducing agent.

In a typical reducing–amination sequence, a carbonyl compound is first reacted with an amine or ammonia to form an imine or iminium ion, followed by the addition of NaBH₃CN and a weak acid catalyst such as acetic acid or pyridinium chloride. The resulting amine product can be isolated by standard work‑up procedures. NaBH₃CN is also employed in the reduction of oximes, hydroxylamines and certain organometallic complexes. In addition, it may be used in the synthesis of cyanoborohydrides of other metal salts, such as lithium or potassium cyanoborohydride, by ion exchange reactions.

The solid is relatively stable to air and moisture; it must be stored in a tightly sealed container at temperatures below 25 °C. When dissolved in a polar solvent, it is highly reactive and should be handled under inert atmosphere to prevent decomposition. Although it is less hazardous than hydrogen cyanide, NaBH₃CN can release hydrogen cyanide vapors upon contact with acids or during accidental decomposition, so it must be used with appropriate ventilation and protective equipment. Disposal should follow local regulations for cyanide-containing wastes, typically involving neutralization with alkaline solution followed by safe segregation to a hazardous waste facility.