Lithium aluminum hydride, abbreviated as LAH, is a very important reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids and amides. Pure lithium aluminum hydride is a white crystalline solid, which is relatively stable in dry air below120 C, but explodes when it meets water.

Preparation method:

1, Schlesinger reaction. The method is that lithium hydride reacts with anhydrous aluminum trichloride in ether. Based on aluminum trichloride, the yield of the reaction was 86%. At the beginning of the reaction, a small amount of lithium aluminum hydride should be added as initiator, otherwise the reaction will take some time to induce, and once it starts, it will proceed at a violent speed, which is prone to accidents.

2. High pressure synthesis method: alkali metal or hydride, aluminum and high pressure hydrogen react in hydrocarbon or ether solvent. In industrial synthesis, sodium aluminum hydride is generally synthesized at high temperature and high pressure, and then undergoes metathesis reaction with lithium chloride.