Natriumborhydrid

Natriumborhydrid, or sodium borohydride (NaBH4), is a white crystalline solid widely used as a reducing agent in organic synthesis. It is a milder hydride donor than lithium aluminum hydride, and its reactivity is compatible with a broad range of substrates under controlled conditions. The compound is relatively stable in dry air but reacts with water and other protic solvents to release hydrogen gas, forming borates.

In typical reductions, NaBH4 efficiently reduces aldehydes and, to a significant extent, ketones to their corresponding primary and secondary alcohols. Reductions are commonly performed in methanol, ethanol, or other alcohol solvents at low to moderate temperatures. Aqueous or alcoholic media can be used, but hydrolysis competes with the desired reduction. NaBH4 generally does not efficiently reduce esters, carboxylic acids, or many amides under standard conditions; however, certain activated substrates or specialized conditions can enable broader reactivity. It can also reduce some nitro groups, imines, and certain conjugated carbonyl compounds under suitable conditions.

Handling and safety: NaBH4 should be stored in a tightly closed container in a dry area away from moisture and acids. It is sensitive to moisture and reacts with water to release hydrogen gas; exposure to acids accelerates gas evolution. It is typically handled under dry solvents or inert atmosphere and with appropriate personal protective equipment. Avoid ignition sources and incompatible materials, and use in a well-ventilated area or fume hood.