Sodium hydride NaH is also a strong reducing agent, often used in organic synthesis.
Although sodium hydride can be prepared by direct reaction of metallic sodium with hydrogen at high temperature, the reaction is incomplete and the yield is low. Instead, metallic sodium is dispersed in mineral oil for hydrogenation synthesis. Although oil dispersible NaH is relatively safe in preparation, storage and transportation, it has a low content (containing 50% sodium hydride) and is inconvenient to use. In some organic reactions, it is necessary to wash with a large amount of reaction solvent to remove mineral oil in NaH.
In 1982, Chinese chemists used the method of metal reduction hydrogenation, using inert salt NaCl as a solid dispersant to directly hydrogenate molten metal sodium to synthesize solid NaH. Results White powdery solid with NaH content up to 80% was obtained. The conversion rate of sodium is more than 98%. The mixture of NaH+NaCl obtained can be directly used to synthesize sodium aluminum hydride NaAlH4. Compared with the oil dispersing NaH method, this method has simple equipment, safe and convenient operation, and greatly reduces the production cost.