History Essay

300 WordsSep 27, 20142 Pages
Sodium borohydride, also known as sodium tetrahydridoborate, and sodium tetrahydroborate[2] is an inorganic compound with the formula NaBH4. This white solid, usually encountered as a powder, is a versatile reducing agent that finds wide application in chemistry, both in the laboratory and on a technical scale. Large amounts are used for bleaching wood pulp.[3][4] The compound is soluble in alcohols and certain ethers but reacts with water in the absence of a base.[5] The compound was discovered in the 1940s by H. I. Schlesinger, who led a team that developed metal borohydrides for wartime applications.[6] Their work was declassified and published only in 1953. Contents 1 Physical properties 2 Structure 3 Synthesis and handling 4 Reactivity 4.1 Coordination chemistry 4.2 Hydrogen source 5 Applications 6 Safety 7 See also 8 References 9 External links Physical properties Sodium borohydride is an odorless white to gray-white microcrystalline powder which often forms lumps. It is soluble in water, but will decompose rapidly in neutral or acidic solutions (only stable at pH 14).[5] The salt can be recrystallized by dissolving in warm (50 °C) diglyme followed by cooling the solution.[7] Solvent Solubility in grams/100 mL[5] MeOH 13 EtOH 3.16 Diglyme 5.15 Et2O insoluble Structure NaBH4 is a salt, consisting of the tetrahedral BH4- anion. The solid is known to exist as three polymorphs: α, β and γ. The stable phase at room temperature and pressure is α-NaBH4, which is cubic and adopts an NaCl-type structure, in the Fm3m space group. At a pressure of 6.3 GPa, the structure changes to the tetragonal β-NaBH4 (space group P421c) and at 8.9 GPa, the orthorhombic γ-NaBH4 (space group Pnma) becomes the most

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