Diborane Reagent

Preparation of Diborane

Laboratory Method
Boron trichloride reacts with lithium aluminium hydride or boron trifluoride ether solution reacts with sodium borohydride gives diborane.
4BCl₃ + 3LiAlH₄ → 2B₂H₆ + 3LiAlCl₄
4BF₃ + 3NaBH₄ → 2B₂H₆ + 3NaBF₄

Applications of Diborane Reagent

Borane is generally used for the reduction of carboxylic acids in the presence of esters, lactones, amides, halides and other functional groups. In addition, borane rapidly reduces aldehydes, ketones and alkenes.

Reduction of Acids, Amides and Nitriles

Diborane is one of the best reagent for the reduction of Acids, Amides and Nitriles.

Reactions with Aldehydes and Ketones

Aldehydes and Ketones are reduced to alcohols with diborane.

Reactions with Lactones

Lactones are reduced to diol with diborane.

Reactions of Alkylboranes

The transformation of alkenes to alcohols proceeds with retention of configuration at the boron bearing carbon.

Hydroboration of Alkenes and Alkynes

Boranes react with alkenes to form alkylboranes that could be oxidized in the presence of alkaline hydrogenperoxide to give alcohols.


Alkynes gives aldehyde with diborane.

Coupling

Alkylboranes on treatment with basic silver nitrate lead to coupling of the alkyl groups.

Examples of Diborane Reagent