7784-21-6 Usage
Chemical Properties
colorless, nonvolatile solid; can be obtained by reacting an ether solution of AlCl3 with LiH; used as a catalyst for organic polymerization processes [MER06]
Physical properties
Colorless cubic crystal; very unstable; decomposes in water; ?Η°? ?11.0 kcal/mol (-46.0kJ/mol).
Uses
Different sources of media describe the Uses of 7784-21-6 differently. You can refer to the following data:
1. As catalyst for polymerizations; reducing agent. Lithium aluminum hydride, q.v. is a more powerful reagent because of its greater soly.
2. Aluminum Hydride is a relatively unstable polymeric covalent hydride that received considerable attention in the mid- 1960s because of its potential as a high energy additive to solid rocket propellants. The projected uses, including aluminum plating, never materialized, and in spite of intense research and development, commercial manufacture has not been undertaken. The synthetic methods developed were costly.
Preparation
Aluminum hydride is prepared by the reaction of lithium hydride with aluminum chloride in diethyl ether.
3LiH + AlCl3 → AlH3 + 3LiCl
General Description
A colorless to white solid.
Air & Water Reactions
Ignites in moist air. Ignites in air with or without oxygen enrichment [Bretherick 1979 p. 221]. Explosively hydrolyzed by water (forms hydrogen gas) [Ruff J.K. Inorg. Synth 1967, 9, 34].
Reactivity Profile
Aluminium hydride is a powerful reducing agent. May react violently with oxidizers. Prolonged exposure to heat may cause spontaneous decomposition. Can also decompose spontaneously at ambient temperature with explosive violence. Occasionally, explosions have occurred when Aluminium hydride was stored in ether. The explosions have been blamed on the presence of carbon dioxide impurity in the ether [J. Amer. Chem. Soc. 70:877 1948]. Can emit toxic fumes on contact with acid or fumes from an acid. [Lewis]. At elevated temperatures, the hydride reduces carbon dioxide or sodium hydrogen carbonate to methane and ethane. These gases are the explosive products formed when CO2 extinguishers have been used during hydride fires. The 1:1 complexes of the hydride (as a complex with ether or dimethylamine) and various tetrazole derivatives are explosive. Tetrazoles include, 2-methyl, 2-ethyl, 5-ethyl, 2-methyl-5-vinyl, 5-amino-2-ethyl, etc., [US Pat. 3 396 170, 1968].
Safety Profile
Hydrides of some metals (such as ASH3 are extremely toxic. Dangerous fire hazard. An unstable material which is spontaneously flammable in air or O2. Evolves explosive H2 upon contact with moisture. Severe explosion hazard by chemical reaction wherein H2 gas is produced, also in contact with methyl ethers contaminated by Con. Mixtures with tetrazole derivatives are explosive. Reacts with oxidzing materials. On contact with acid or acid fumes, it can emit toxic fumes. See also HYDRIDES and ALUMINUM COMPOUNDS.
Check Digit Verification of cas no
The CAS Registry Mumber 7784-21-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,7,8 and 4 respectively; the second part has 2 digits, 2 and 1 respectively.
Calculate Digit Verification of CAS Registry Number 7784-21:
(6*7)+(5*7)+(4*8)+(3*4)+(2*2)+(1*1)=126
126 % 10 = 6
So 7784-21-6 is a valid CAS Registry Number.
InChI:InChI=1S/Al.3H
7784-21-6Relevant articles and documents
Catalytic synthesis of aluminum hydride in the presence of palladium black
Normatov
, p. 558 - 560 (2004)
The catalytic properties of a palladium catalyst in the formation of aluminum hydride are studied. The formation of stoichiometric aluminum hydride is determined by XRD, DTA, and spectrophotometry. Findings are rationalized in terms of the electron-chemical catalytic scheme.
Surface changes on AlH3 during the hydrogen desorption
Kato, Shunsuke,Bielmann, Michael,Ikeda, Kazutaka,Orimo, Shin-Ichi,Borgschulte, Andreas,Zuettel, Andreas
, (2010)
Surface change of α -AlH3 during the hydrogen desorption was investigated by means of in situ x-ray photoelectron spectroscopy combined with thermal desorption spectroscopy. The surface of AlH3 covered by an oxide layer significantly changes upon hydrogen desorption and the hydrogen desorption rate increases remarkably. In this study, the role of the surface oxide layer on AlH3 in view of the hydrogen desorption kinetics was investigated. AlH3 only decomposes into Al and H2 at the free surface and not in the bulk. Therefore, a closed surface oxide layer prevents the thermodynamically unstable AlH3 from decomposition.
Aluminium hydride: A reversible material for hydrogen storage
Zidan, Ragaiy,Garcia-Diaz, Brenda L.,Fewox, Christopher S.,Stowe, Ashley C.,Gray, Joshua R.,Harter, Andrew G.
, p. 3717 - 3719 (2009)
Aluminium hydride has been synthesized electrochemically, providing a synthetic route which closes a reversible cycle for regeneration of the material and bypasses expensive thermodynamic costs which have precluded AlH3 from being considered as
Oxazolidines as Intermediates in the Asymmetric Synthesis of 3-Substituted and 1,3-Disubstituted Tetrahydroisoquinolines
Raghavan, Sadagopan,Senapati, Puspamitra
, p. 6201 - 6210 (2016/08/16)
A diastereoselective mercury(II)-promoted intramolecular cyclization of unsaturated aldehyde via an oxazolidine to prepare C-3-substituted tetrahydroisoquinoline is disclosed. The C-3 stereogenic center is subsequently exploited to create the C-1 stereocenter by coordination of the nucleophilic reagent to the oxygen atom of oxazolidine. Both cis- and trans-1,3-disubstituted tetrahydroisoquinolines can be readily prepared. In addition, when a cationic rhodium complex was used, intramolecular hydroamination was effected, thus avoiding mercury(II) salts and demercuration. The reaction is general and works well using aliphatic and aromatic aldehydes.
Hydrogen release reactions of Al-based complex hydrides enhanced by vibrational dynamics and valences of metal cations
Sato,Ramirez-Cuesta,Daemen,Cheng,Tomiyasu,Takagi,Orimo
supporting information, p. 11807 - 11810 (2016/10/09)
Hydrogen release from Al-based complex hydrides composed of metal cation(s) and [AlH4]- was investigated using inelastic neutron scattering viewed from vibrational dynamics. The hydrogen release followed the softening of translational and [AlH4]- librational modes, which was enhanced by vibrational dynamics and the valence(s) of the metal cation(s).
