Tetrahydro borate

Eine einfache Methode zur Herstellung von /,2,3,4-Tetrahydro-chinoIin aus Chinolin besteht in der Reduktion mit Natrium-cyano-trihydrido-borat in Essigsaure (N-Alkylie-rung tritt dabei nicht auf)6 ... 

Mit Natrium-cyano-trihydrido-borat in protischer Losung werden dagegen 1,2,5,6-Tetrahydro-pyridine erhalten 5. 

Zucker-(tosyl-hydrazone) werden mit Natrium-cyano-trihydrido-borat in Tetrahydro-furan/Methanol in Desoxyzucker iibergefiihrt5. 

Borazine originally was obtained by the reaction of ammonia with diborane.1 Mixtures of lithium or sodium tetrahydro-borate with ammonium chloride also have been pyrolyzed to yield this product.2 More recently, the reduction of B,B, B"-trichloroborazine with alkali metal hydroborates has proved to be a convenient laboratory-scale method for the preparation of this compound.3-7 The procedure described herein is a variation of the last method as reported by Dahl and Schaeffer.7 This method is effective for the synthesis of iV-substituted alkyl- and arylborazines, i.e., compounds of the formula (HBNR)3 where R is CH3, C2H6, C6H , C6H5, p-C6H4CH3, or p-C6H4OCH3.5... 

Dimethyl sulfoxide Methyl sulfoxide (8) Methane, sulfinylbis- (9) (67-68-5) Sodium borohydride Borate(l-), tetrahydro-, sodium (8,9) (16940-66-2)... 

Pyrrolidino- bzw. 3-Piperidino-acrylsaure-ester cyclisieren mit Phenyldiazonium-tetrafluoro-borat unter Einbau eines N-Atoms aus dem Diazonium-Salz zu 2-Methoxy carbonyl-6,7-di-hydro-5 H-yrrolo[l, 2-d imidazol ) (40%) bzw. 2-Methoxycarbonyl-5,6,7,8-tetrahydro-[Pg.59]

Uranium Borohydride [Uranium (III) tetrahydro-borate]. U(BH4)3 mw 28258 green pyrophoric crysts, volatile at RT mp >70° (22mm Hg) bp, explds on heating. Reacts with water and methanol. Prepn is by reacting U (IV) fluorides with an excess of A1 borohydride... 

Zirconium Borohydride (Zirconium Tetrahydro-borate). Zr(BH4)4 mw 150.5 volatile pyrophoric cryst mp 28.7° bp 123° (extrapolated) d l.l3g/cc. Prepn is by reacting Zr tetrachloride with Li borohydride — the yield is 77%. Accdg to Gaylord (Ref 4) the compd is spontaneously flammable in air... 

Ashby, E. C., Kept. AD-A057764, Richmond (Va.), USNTIS, 1978 This class of highly reactive compound includes several which have found extensive use in preparative chemistry [ 1 ]. Properties and reactions of several covalent tetrahydro-borates have been reviewed [2]. Preparation and properties of several new hydrides are given which are of interest as high-energy fuels in propellant systems [3]. Individually indexed compounds are ... 

This section does not review comprehensively all the tetrahydro-borate derivatives, since these have been adequately covered elsewhere (50). The aluminohydride compound Cp2Zr(H)AlH4 has been mentioned, but several similar hydrides have been identified. Such compounds are relevant in particular to known reactions where titanium(IV) or zirconium(IV) compounds catalyze the addition of Al-H bonds to alkenes and alkynes (114, 115). 

Calcium bis[tetrahydroborate(l-)] may be prepared from sodium tetra-hydroborate( 1 -) and calcium dichloride by cation exchange11 in a suitable solvent such as dimethylformamide,12 an amine13,14 or an alcohol.13,14 A particularly good preparation of very pure Ca[BH4]2 involves the reaction of calcium dihydride with the triethylamine-borane adduct.15,16 This method may also be used for the preparation of other tetrahydroborates of alkali and alkaline earth metals. The triethylamine-borane adduct17 may be synthesized in a variety of ways, e.g., from triethylamine, sodium tetrahydro-borate(l —), and trichloroborane 18 from a trialkoxyborane, aluminum metal, and hydrogen in the presence of triethylamine 19 or by hydrogenation under pressure of a mixture of triethylborane and triethylamine.20 The triethylamine-borane adduct is a colorless liquid (mp — 2°). It is stable to air and moisture at room temperature and it is easily purified by vacuum distillation (bp 95-96°/12 torr). 

---