Illustrated Glossary of Organic Chemistry

Sodium borohydride: The sodium salt of the tetrahydridoborate anion; Na+ BH4-. A reducing agent, principally for the chemoselective reduction of carbonyl compounds.

Lewis structure of sodium borohydride.

Sodium Borohydride Reduction of Carbonyl Compounds

NaBH4 reduces an aldehyde to a primary alcohol.

NaBH4 reduces a ketone to a secondary alcohol.

NaBH4 reduces an acid chloride to a primary alcohol.

NaBH4 does not reduce an amide or an ester.