Reduction of ketones [NaBH4]
Reduction of ketones [NaBH4] Definition:
Addition of sodium borohydride (NaBH4) to ketones gives secondary alcohols (after addition of acid).
Reduction of ketones [NaBH4] Explained:
Reduction, in organic chemistry, means the addition of hydrogen to molecule or removal of electronegative atoms such as halogen or oxygen from the molecule.
Hydride, by itself, is not a good nucleophile because it is not polarizable. But sodium borohydride, NaBH4 function as a delivery agent of nucleophilic hydride anion. And the solvent function as the source of a proton. The solvent can be ethanol, methanol, or water.
In this medium, the reagent donates hydride to the carbonyl carbon with simultaneous protonation of the carbonyl oxygen by the solvent. The intermediate which is obtained by first transferring of the hydride ion can attack three more carbonyl substrates until all the hydride atoms of the original reagent have been used up. Thus one equivalent of borohydride is capable of reducing four equivalents of a ketone to a secondary alcohol.