Sodium triacetoxyborohydride

Sodium triacetoxyborohydride, also known as sodium triacetoxyhydroborate, commonly abbreviated STAB, is a chemical compound with the formula Na(CH₃COO)₃BH. Like other borohydrides, it is used as a reducing agent in organic synthesis. This colourless salt is prepared by protonolysis of sodium borohydride with acetic acid:

Owing to the steric and electronic effects of the acetoxy groups, sodium triacetoxyborohydride is a milder reducing agent than sodium borohydride or even sodium cyanoborohydride. Furthermore, NaBH(OAc)₃ avoids the toxic side-products generated by sodium cyanoborohydride. Sodium triacetoxyborohydride is especially suitable for reductive aminations of aldehydes and ketones.

However, unlike sodium cyanoborohydride, the triacetoxyborohydride is water-sensitive, and water cannot be used as a solvent with this reagent, nor is it compatible with methanol. It reacts only slowly with ethanol and isopropanol and can be used with these.

NaBH(OAc)₃ may also be used for reductive alkylation of secondary amines with aldehyde-bisulfite adducts.