Lithium Aluminum Hydride (LiAlH4) is a strong reducing agent used in organic chemistry to reduce polar multiple bonds like C=O. It is more powerful than the related reagent sodium borohydride (NaBH4) due to the weaker Al-H bond compared to the B-H bond. LiAlH4 can reduce aldehydes to primary alcohols, ketones to secondary alcohols, and carboxylic acids, esters, lactones, acid halides, and anhydrides to primary alcohols. It can also reduce nitriles and amides to amines and open epoxides as well as reduce alkyl halides to alkanes. Lithium Aluminum Hydride does not reduce simple alkenes or arenes, and alkynes are reduced only if an alcohol group is nearby. The reactions are usually performed with excess LiAlH4, and water is usually added in a second step.

It's important to note that lithium aluminum hydride is a strong reducing agent and must be handled with care. It reacts violently with water, so reactions involving LiAlH₄ are often carried out in a dry, inert atmosphere. Additionally, the reactions are typically quenched by the addition of a protic solvent such as water or methanol after completion to destroy excess LiAlH₄ and the aluminum-containing byproducts.