Title: Lithium Borohydride
CAS Registry Number: 16949-15-8
CAS Name: Lithium tetrahydroborate
Molecular Formula: BH4Li
Molecular Weight: 21.78
Percent Composition: B 49.64%, H 18.51%, Li 31.87%
Line Formula: LiBH4
Literature References: Prepd by the action of diborane on ethyllithium; by the action of aluminum borohydride on ethyllithium: Schlesinger, Brown, J. Am. Chem. Soc. 62, 3429-35 (1940). Review of lithium and other metal tetrahydroborates: James, Wallbridge, Prog. Inorg. Chem. 11, 99-231 (1970).
Properties: Orthorhombic crystals, mp 268°; dec 380°. d 0.66. Stable under ordinary conditions, but dec in moist air. Reacts with hydrogen chloride to form hydrogen, diborane, and lithium chloride; forms lithium boromethoxide and hydrogen with methyl alcohol. Sol in water at pH >7. Aq solns dec slowly if the pH is >7, and rather vigorously when acidified. Sol in ether, tetrahydrofuran, aliphatic amines.
Melting point: mp 268°
Density: d 0.66
Use: Strong reducing agent. Used in the reduction of compds contg ketonic, aldehydic, or ester carbonyls and a nitrile group, where reduction of the carbonyl, but not of the nitrile group, is wanted. In the determination of free carboxyl groups in peptides and proteins; after esterification and acetylation, only the ester groups, and none of the peptide bonds are reduced. |