The chemical formula of sodium hydride is NaH, CAS No. 7646-69-7. It is usually a white to off-white crystalline powder or lump solid, odorless, and hygroscopic. Insoluble in organic solvents (such as ether and benzene), it reacts violently with water to generate sodium hydroxide and release a large amount of hydrogen gas. The reaction is accompanied by high heat, which may cause hydrogen combustion or even explosion. It is highly reducing and strongly basic, and is often used as a strong base and hydride ion donor in organic reactions. It can react violently with acids, oxidants, halogenated hydrocarbons, etc. It slowly deteriorates in air or moist environments. When heated above 400°C, it decomposes into sodium metal and hydrogen gas. Industrially, it is mainly used in organic synthesis (as a strong base catalyst for condensation and cyclization reactions, or as a reducing agent to prepare organometallic compounds), metal smelting (reducing certain metal oxides to extract metals); it is also used to prepare chemical products such as sodium borohydride.