Sodium borohydride is a milder reducing agent, can be used in aqueous solution. It converts selectively aldehydes and ketones the corresponding alcohols in the manufacture of pharmaceuticals and other fine chemicals. It will not react with esters, amides, or carboxylic acids, the more powerful reducing agent lithium aluminum hydride(LAH) is used to reduce these compounds. LAH is the more powerful reducing agent than sodium borohydride due to the weaker Al-H bond compared to the B-H bond.
The reactivity of sodium borohydride can be modified by addition of iodine or methanol in BH3-THF to reduce esters into the corresponding alcohols like the reaction of benzyl benzoate to benzyl alcohol. Sodium borohydride is used as a hydrogen source for fuel cell systems and a foaming agent for rubbers. Sodium cyanoborohydride converts certain alcohol groups to methylene groups. Sodium Cyanoborohydride is used as a selective amination reductant. It converts aldehydes (chemoselective), ketones (stereoselective) to the corresponding alcohols in the manufacture of pharmaceuticals and other fine chemicals. It is used in the reductive alkylation of amines, novel metals and oximes.