Stability of lithium hydride in argon and air

The oxidation behaviors of LiH under a high purity argon atmosphere, an argon atmosphere with some O2 and H2O impurities, and ambient air at both room and high temperatures, are investigated using a variety of analytical instruments including X-ray diffractometry, thermogravimetry, mass spectrometry, scanning electron microscopy, and specific surface area analysis. The oxidation behaviors of the ball-milled LiH under different atmospheres are also studied and compared with those without ball milling. It is shown that no oxidation of LiH occurs under a high-purity argon atmosphere. However, oxidation of LiH takes place when the argon atmosphere contains some H2O and O2 impurities. At temperatures higher than approximately 55 degrees C, oxidation of LiH proceeds via the reaction of LiH + 1/4 O2 = 1/2 Li2O + 1/2 H2, whereas at room temperature oxidation of LiH is likely caused by the simultaneous reactions of LiH + H2O = LiOH + H2 and LiH + 1/2 O2 = LiOH. The oxidation behavior of LiH in ambient air with a 27% relative humidity can be well described by the Johnson-Mehl-Avrami equation. Furthermore, the ball-milled LiH oxidizes faster than the unmilled one, which is due to the finer particle size and larger surface area of the ball-milled powder.     

Reduction of diarylphthalides with aluminum lithium hydride

Conclusions The reduction of diarylphthalides with LiA1H₄ in THF leads to the corresponding diarylphthalans.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, p. 686, March, 1979.     

Interaction of lithium hydride and ammonia borane in THF

The two-step reaction between LiH and NH(3)BH(3) in THF leads to the production of more than 14 wt% of hydrogen at 40 degrees C.     

Intramolecular hydride transfer in the ionic hydrogenation of isopropylcyclopropane

Conclusions It was shown that in the ionic hydrogenation of isopropylcyclopropane simultaneously with cleavage of the ring there is an intramolecular hydride transition with the formation of a tertiary carbonium ion, which splits a hydride ion from silane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 746–748, April, 1969.     

The lithium aluminium hydride reduction of cyclohexadienylmanganese complexes

Reduction of cyclohexadienyltricarbonylmanganese or its ring-substituted derivatives with lithium aluminium hydride leads to dihydro-derivatives. Preparative and NMR spectral information is presented and interpreted on the basis of the CH-bridged cyclohexenyl structure recently established for these products by Lamanna and Brookhart [3].     

Secondary emission of doped lithium hydride single crystals

Experimental studies of resonance Raman scattering (RRS) and of luminescence of excitons interacting with an impurity field and phonons in lithium hydride (LiH) crystals doped with Al, Mg, and Zn have been made. It has been shown that the presence of doped metal ions modifies the relaxation processes of excitons in the LiH lattice and gives rise to bound excitons with large and small radii.     

Catalytic synthesis of lithium hydride under mild conditions

A catalyst composed of titanium tetrachloride and naphthalene or its methyl derivatives with very high activity was found for the synthesis of LiH. Metallic lithium can be quantitatively hydrogenated to lithium hydride at 25–50°C under atmospheric pressure within 2–5 h according to various catalyst compositions. The catalyst stability was investigated and the relationship between catalyst compositions and reaction controlling step was established also.     

温和条件下氢化锂的催化合成

本文提出了一种温和条件下合成氢化锂的方法,催化剂是由萘或萘的甲基衍生物和TiCl4组成,具有很高的活性。它可以使金属锂在25-50℃常压加氢,根据催化剂的不同组成,锂可以在2～5小时内定量地转化成氢化锂,考察了催化剂的稳定性,并确定了催化剂组成和控制反应步骤之间的关系。     

A supersonic beam of cold lithium hydride molecules

We have developed a source of cold LiH molecules for Stark deceleration and trapping experiments. Lithium metal is ablated from a solid target into a supersonically expanding carrier gas. The translational, rotational, and vibrational temperatures are 0.9+/-0.1, 5.9+/-0.5, and 468+/-17 K, respectively. Although they have not reached thermal equilibrium with the carrier gas, we estimate that 90% of the LiH molecules are in the ground state, X (1)Sigma(+)(v=0,J=0). With a single 7 ns ablation pulse, the number of molecules in the ground state is 4.5+/-1.8 x 10(7) molecules/sr. A second, delayed, ablation pulse produces another LiH beam in a different part of the same gas pulse, thereby almost doubling the signal. A long pulse, lasting 150 micros, can make the beam up to 15 times more intense.     

Azeotropic phenomena in a dilute solution of lithium hydride in lithium at liquid-vapor phase equilibrium

A Li-LiH-type system under liquid-vapor phase equilibrium conditions was considered. Liquid is a binary infinitely dilute solution of lithium hydride in lithium, and the coexisting vapor phase is a multi-component chemically reacting ideal mixture of gas components. The phenomenon of the existence of azeotropy in such systems, earlier unknown, was established. The concentration of the components was expressed in the atomic fractions of hydrogen in both phases. The temperature and concentration boundaries of the azeotropic zone were found. The trends revealed are of importance for applications.     

All-electron calculations with plane waves in solid lithium hydride

Calculations of the directional Compton profiles and the anisotropies of Compton scattering are reported, based on the density functional theory in the local density approximation, performed in the plane-wave basis, and using full, unscreened Coulomb potentials for both Li and H atoms. It is shown that converged results can be obtained without employing pseudopotentials, and the Compton profiles obtained are in excellent agreement with experiment. The influence of correlation on Compton profiles in LiH is found to be very weak. Possibilities (and limits) of extending the plane-wave calculations with the full Coulomb potentials to other atoms and substances are discussed. © 1997 John Wiley & Sons, Inc.