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Sodium borohydride is a kind of inorganic substance, chemical formula is NaBH4, white to gray white fine crystalline powder or block, hygroscopic strong, its alkaline solution is brownish yellow, is one of the most commonly used reductants. Soluble in water, liquid ammonia, amines. Soluble in methanol, slightly soluble in ethanol, tetrahydrofuran. Insoluble in ether, benzene, hydrocarbon. Stable in dry air, decomposition in wet air, 500℃ heating decomposition. In general, sodium borohydride cannot reduce esters, amides, carboxylic acids, and nitriles, except in the presence of heteroatoms in the carbonyl α position of the ester.
Sore throat, cough, shortness of breath, headache, abdominal pain, diarrhea, dizziness, conjunctival congestion, pain and other symptoms after contact with sodium borohydride. Harmful to human health by inhalation or skin contact.
The reagent is commonly used as a reducing agent for aldehydes, ketones and acyl chlorides, as a foaming agent in the plastics industry, as a bleaching agent for paper making, and as a hydrogenating agent for dihydrostreptomycin in the pharmaceutical industry. Sodium borohydride should be kept dry and carefully operated in a fume hood. Should be stored in a cool, dry warehouse, away from heat and fire and flammable items, do not store mixed transport with inorganic acid.
Sodium borohydride was discovered by H. C. Brown and his mentor Schlesinger at the University of Chicago in 1942. In order to study the properties of borane and carbon monoxide complex, but accidentally found that borane has the ability to reduce organic carbonyl compounds. Because boranes were rare, organic chemists didn't pay much attention to them. Borane chemistry was developed during World War II, when the U.S. Department of Defense sought a volatile uranium compound with the smallest molecular weight for enrichment of the fissile material U-235. Uranium borohydride U (BH4) 4 meets this requirement. The compound's synthesis requires lithium hydride, which is in short supply, so cheap sodium hydride is used as a feedstock, and sodium borohydride is found in this process. Later, when the U.S. Department of Defense abandoned plans to enrich URANIUM 235 through uranium borohydride because of processing problems with uranium hexafluoride, Brown's research topic became how to make sodium borohydride easily. Army Signal Corps was interested in how the new compound could be used to produce large amounts of hydrogen. With their funding, relevant industrialization research was carried out. Pure sodium borohydride was obtained by recrystallization with ethers.