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The addition of triethylamine to a solution of aluminum hydride in tetrahydrofuran (THF), which was prepared by the addition of a calculated amount of hydrogen chloride in diethyl ether to solutions of sodium aluminum hydride in THF, provides very stable solutions of aluminum hydride-triethylamine complex (AHTEA). The reducing power of AHTEA complex in tetrahydrofuran toward 59 selected organic compounds containing representative functional groups under practical conditions (tetrahydrofuran, room temperature, the quantitative amount of reagent to compound) has been investigated. In this way, we have established that quantitative reduction of various organic functionalities can be readily achieved using the calculated quantity of AHTEA to avoid the use of excess reagent

(1994). REDUCTION OF ORGANIC COMPOUNDS WITH SODIUM ALUMINUM HYDRIDE IN THEORETICAL AMOUNT. Organic Preparations and Procedures International: Vol. 26, No. 4, pp. 459-464.

Asymmetric reduction of ketones with hydride complexes, which were prepared by in situ modification of NaAlH4, with various chiral amino alcohols or diamines, was studied. The highest enantioselectivity (up to 93% ee) was achieved using 2-(hydroxydiphenylmethyl)pyrrolidine as a chiral inducing agent.

On the basis of density functional theory (DFT) and coupled cluster (CCSD(T)) calculations we propose a mechanism of dehydrogenation of titanium doped sodium aluminum hydride (NaAlH4). The mechanism is deduced from studies on the decomposition of a minimal cluster model system consisting of one Ti atom and two NaAlH4 units. Its relevance to the real-world materials is subsequently tested by periodic DFT calculations on systems created by embedding the minimal clusters into the (001) surface of the NaAlH4 crystal. It is found that the dehydrogentaion proceeds via breaking of the bridge H-Al bond and subsequent formation of a weak intermediate compound in which the H2 molecule is side-on (hapto) bonded to the transition metal centre. This means that the total barrier to the H2 release is dependant upon both the strength of the Al-H bond to be broken and the depth of the coordinative potential. The analogous mechanism applies for the recognized three successive dehydrogenation steps. The gas-phase optimized model structures embedded into the surface of the NaAlH4 crystal exhibit an unambiguous kinetic stability and their general geometric features remain largely unchanged. This motivated us to calculate the kinetic parametres of the de- and re-hydrogenation of the gas-phase minimal clusters making use of the variable reaction coordinate (VRC) and quasi-classical trajectories treatments. To accomplish this, we developed a model potential up to the 5-body terms treating 6 of the 13 atoms (3H, 2Al and Ti) as active. The potential as a function of 15 internuclear Morse-type coordinates is expanded in a polynomial basis that is made invariant with respect to change of the atoms of the same type. The obtained results will be compared to the experimental de- and re-hydrogenation curves.

A comparative study of the dehydrogenation of pure, ScCl3-, TiCl3-, VCl3-, and MnCl2-doped sodium alanate is reported. The samples wet-doped with transition metal halides exhibit significant lowering of both first and second dehydrogenation temperatures when compared with the pure sodium alanate. The reduction of the dehydrogenation temperature, ΔTdec, is maximum for the VCl3-doped alanates: 37 and 55 °C, respectively, for the decomposition steps yielding Na3AlH6 and NaH. Among the transition metal halides, the order in which the decomposition temperature is lowered is Mn

Wall pressure exerted by the bulk expansion of a sodium aluminum hydride bed was measured as a function of hydrogen content. A custom apparatus was designed and loaded with sodium alanates at densities of 1.0, 1.1, and 1.16 g/cc. Four complete cycles were performed to identify variations in measured pressure. Results indicated poor correlation between exerted pressure and hydrogen capacity of the sodium alanate beds. Mechanical pressure due to the hydrogenation of sodium alanates does not influence full-scale system designs as it falls within common design factors of safety. Gas pressure gradients within the porous solid were identified and may limit reaction rates, especially for high aspect ratio beds.

New stereoselective reducing reagents were preparedin situ by modification of NaAlH4 with various chiral diols. The efficiency of 1,4- and 1,3-diols as chiral auxiliaries in the reactions of alkyl aryl ketones with modified NaAlH4 was considerably higher than that of 1,2-diols. The effect of the nature of the achiral ligand additionally introduced into the chiral hydride reagent on the enantioselectivity of ketone reduction was studied. It was proposed that the sodium cation does not necessarily participate at the stage governing the reaction stereochemistry.

Na3AlH6 can be directly formed by mechanical milling NaH/Al with TiF3 under hydrogen atmosphere. The hydrogenation fraction of NaH increases with increasing the milling time, and reaches up to 0.61 after 20 h milling. Thus-formed Na3AlH6 exhibits unexpected polymorphic transformation and decomposition behaviors. This, together with the unusual hydrogen storage performance of the mechanically prepared materials, provides us a suggestive perspective to probe the favorable modification of the thermodynamics of Na3AlH6 and nature of active Ti-species in Ti-doped NaAlH4. (C) 2005 American Institute of Physics.

The reduction of complex esters and carbonyl compounds in hydrocarbon media by aluminum hydrides of the alkali metals results in the formation of the corresponding alcohol in high yield. The reduction of nitriles proceeds with the formation of primary amines.

1. Sodium aluminum hydride reacts withα-olefins in the presence of such catalysts as AlR3, HAlR2, ClAlR2, AlX3, LiX, ZnX2, and LiAlH4 (X represents halogen), forming complexes with the structure NaAlR4. 2. In the oxidation of tetraalkyl complexes, alcohols are formed in high yields.

1. Interaction in the NaAlH4 — THF system has been investigated in the temperature range −110 to 25° by the differential thermal, visual polythermal, and isothermal solubility methods. 2. The existence of two compounds has been established, NaAlH4·8THF and NaAlH4·4THF; these melt incongruently at −51 and −32°, respectively. 3. The solubility of NaAlH4 in THF has been determined at the following temperatures: −75, −50, −30, 0, and 25°C; under these conditions its molar and weight concentrations are, respectively, 1.4, 1.05; 11.6 8.95; 19.8, 15.60; 21.06, 16.68; and 22.13, 17.51%.

Sodium aluminum hydride reduces carboxylate esters and lactones in good yield to the corresponding aldehydes and hydroxy aldehydes.