Sodium aluminum hydrides

Sodium Aluminum Hydride. Sodium aluminum hydride can be prepared from NaH,... 

A 50-galIon stirred pot reactor was used for the production of sodium aluminum hydride, which reacts exothermally with water with enough heat to cause the hydrogen that is released to explode. 

He did not put on the fire gear and proceeded to open the vessel and hose it out with a fire hose. An explosion resulted when water f dislodged crusted-over sodium aluminum hydride trapped in a nozzle. The worker was burned, requiring a two-week hospital stay and several months of recuperation. 

Bis(Methoxy-2-ethoxy)sodium aluminum hydride (lndolyl-3)(piperidinyl-4-methyl)ketone... 

Bis(methoxy-2-ethoxy) sodium aluminum hydride Indalpine... 

Sodium aluminate, 2 345t, 358-359 analysis, 2 275-276 economic aspects, 2 275 health and safety factors, 2 276 manufacture, 2 274-275 neutralization, 2 424 physical and chemical properties of, 2 273-274 uses of, 2 276-277 in water treatment, 26 111 Sodium aluminosilicate gels, synthetic zeolites prepared from, 16 831t Sodium aluminosilicates, 12 578 Sodium aluminum hydride, 13 621, 623-624... 

Waste heat from the fuel cell is used to reverse the reaction and release the fuel. In 2005 GM and Sandia National Laboratories launched a 10-million program to develop metal hydride storage systems based on sodium aluminum hydride. 

Bogdanovic, B., Brand, R.A., Marjanovie, A., Sehwikardi, M., Tolle, J. 2000. Metal doped sodium aluminum hydrides as potential new hydrogen storage materials. J Alloys Comp 302 36-58. 

Jensen, C.M., Zidan, R., Mariels, N., Hee, A., Hagen, C. 1999. Advanced titanium doping of sodium aluminum hydride segue to a practical hydrogen storage material Int J Hydrogen Energy 24 461 65. 

J. Wang, A.D. Ebner, R. Zidan, J.A. Ritter, Synergistic effects of co-dopants on the dehydrogenation kinetics of sodium aluminum hydride , J. Alloys Compd. 391 (2005) 245-255. 

E.C. Ashby, R.D. Schwartz, B.D. James, Concerning the preparation of magnesium aluminum hydride. A study of the reactions of lithium and sodium aluminum hydrides with magnesium halides in ether solvents , Inorg. Chem. 9 (1970) 325-332. 

Contact with water may ignite sodium aluminum hydride. 

Complex aluminum and boron hydrides can contain other cations. The following compounds are prepared by metathetical reactions of lithium aluminum hydride or sodium borohydride with the appropriate salts of other metals sodium aluminum hydride [55], magnesium aluminum hydride [59], lithium borohydride [90], potassium borohydride [9i], calcium borohydride [92] and tetrabutylammonium borohydride [95]. 

The pyridine ring is easily reduced in the form of its quaternary salts to give hexahydro derivatives by catalytic hydrogenation [446], and to tetrahydro and hexahydro derivatives by reduction with alane aluminum hydride) [447], sodium aluminum hydride [448], sodium bis 2-methoxyethoxy)aluminum hydride [448], sodium borohydride [447], potassium borohydride [449], sodium in ethanol [444, 450], and formic acid [318]. Reductions with hydrides give predominantly 1,2,5,6-tetrahydro derivatives while electroreduction and reduction with formic acid give more hexahydro derivatives [451,452]. 

If the quaternary nitrogen is a member of a ring, the ring is cleaved. 3-Benzyl-2-phenyl-A, A -dimethylpyrrolidinium chloride was cleaved by hydrogenation over Raney nickel at 20-25° almost quantitatively to 2-benzyl-4-dimethylamino-l-phenylbutane [722]. Reduction of methylpyridinium iodide (and its methyl homologs) with sodium aluminum hydride gave 24-89% yields of 5-methylamino-l,3-pentadiene (and its methyl homologs) in addition to A -methyl dihydro- and tetrahydropyridine [448]. 

Reduction of aromatic carboxylic acids to alcohols can be achieved by hydrides and complex hydrides, e.g. lithium aluminum hydride 968], sodium aluminum hydride [55] and sodium bis 2-methoxyethoxy)aluminum hydride [544, 969, 970], and with borane (diborane) [976] prepared from sodium borohydride and boron trifluoride etherate [971, 977] or aluminum chloride [755, 975] in diglyme. Sodium borohydride alone does not reduce free carboxylic acids. Anthranilic acid was reduced to the corresponding alcohol by electroreduction in sulfuric acid at 20-30° in 69-78% yield [979],... 

Esters are also reduced by sodium aluminum hydride (yields 95-97%) [<9<9] and by lithium trimethoxyaluminum hydride (2 mol per mol of the ester) [94] but not by lithium tris tert-butoxy)aluminum hydride [96], Another complex hydride, sodium bis(2-methoxyethoxy)aluminum hydride, reduces esters in benzene or toluene solutions (1.1 -1.2 mol per ester group) at 80° in 15-90 minutes in 66-98% yields [969], Magnesium aluminum hydride (in the form of its tetrakistetrahydrofuranate) reduced methyl benzoate to benzyl alcohol in 58% yield on refluxing for 2 hours in tetrahydrofuran [59]. 

Sodium combines with hydrogen forming sodium hydride, NaH. The reaction is slow at ambient temperature but proceeds rapidly above 200°C when the metal is dispersed or spread over the surface of an inert solid (such as a hydrocarbon). Sodium and hydrogen react with aluminum powder to form sodium aluminum hydrides. Two such complex hydrides, the tetrahydride, NaAlH4, and the hexahydride, NasAlHe, are produced. The nature of the prod-... 

Sodium aluminum hydride can he prepared from NaH. but direct synthesis from the elements is more economical. 

The most important compound is lithium aluminum hydride, LiAlHt, a nonvolatile crystalline solid, stable below 120°C, that is explosively hydrolyzed by water. In the crystal there are tetrahedral AlHf ions with an average A1H distance of 1.55 A. The Li+ ions each have four near hydrogen neighbors (1.88 - 2.00 A) and a fifth that is more remote (2.16 A). Lithium aluminum hydride is soluble in diethyl and other ethers and can be solubilized in benzene by crown ethers. In ethers, the Li+, Na+, and R4N+ salts of A1H and GaH4 tend to form three types of species depending on the concentration and on the solvent, namely, either loosely or tightly bound aggregates or ion pairs. Thus LiAlHt is extensively associated in diethyl ether, but at low concentrations in THF there are ion pairs. Sodium aluminum hydride (NaAlH) is insoluble in diethyl ether. 

Sodium aluminum hydride can be synthesized by many different routes. The first preparation was performed by the reaction of NaH and AlBr3 in the presence of dimethyl ether as a solvent [92]. The direct synthesis from NaH and A1 under elevated hydrogen pressures and in various solvents is possible [59, 60]. However, sodium aluminum hydride can also be synthesized by melting the elements in the absence of any solvents (Eq. (5.22)) [93[. 

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