Sodium cyanoborohydride is the

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the formula Na B H₃ CN. It is a colourless salt, but commercial samples can appear tan. It is widely used in

organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...

for the reduction of imines. The salt tolerates aqueous conditions.

Use

Owing to the presence of the electron-withdrawing

cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...

substituent, (CN)H₃sup>− is less reducing than is H₄sup>−. As a mild reducing agent, it is used to convert imines to

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...

s. It is especially favored for reductive aminations, wherein aldehydes or ketones are treated with an amine in the presence of this reagent: : R₂CO + R'NH₂ + NaBH₃CN + CH₃OH → R₂CH-NHR' + "NaCH₃OBH₂CN" The reagent is typically used in excess. Selectivity is achieved at mildly basic solutions ( pH 7–10). The reagent is ideal for reductive aminations ("Borch Reaction"). In conjunction with tosylhydrazine, sodium cyanoborohydride is used in the reductive deoxygenation of

ketones In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bon ...

Structure and preparation

The tetrahedral BH₃(CN)⁻ comprises the anionic component of the salt. The reagent is often purchased, although it can be prepared easily. One method involves combining sodium cyanide and borane. Another route entails treating sodium borohydride with

mercury(II) cyanide Mercury(II) cyanide, also known as mercuric cyanide, is a compound of mercury. It is an odorless, toxic white powder. It is highly soluble in polar solvents such as water, alcohol, and ammonia; slightly soluble in ether; and insoluble in benzene a ...

. The commercial samples can be purified, but the yields of the reductive aminations do not improve.

References

Borohydrides Sodium compounds Reducing agents {{inorganic-compound-stub

Use

Structure and preparation

See also

References