User:Pep-k/Lithium tetrahydridogallate
| Names | |
|---|---|
| Other names
Lithium gallium hydride
Lithium tetrahydrogallate | |
| Identifiers | |
| Properties | |
| LiGaH4 | |
| Molar mass | 80.7 g/mol |
| Appearance | white crystals (pure samples) |
| Melting point | 70 °C (158 °F; 343 K) (decomposes) |
| Reacts | |
| Related compounds | |
Related hydride
|
Gallium hydride Sodium tetrahydridogallate Potassium tetrahydridogallate Cesium tetrahydridogallate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
| Names | |
|---|---|
| IUPAC name
Lithium tetrahydridogallate
| |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
Lithium tetrahydridogallate is the inorganic compound with formula LiGaH4. It was first prepared by Finholt, Bond and Schlesinger[1] in1947.
Synthesis[edit]
Lithium tetrahydrogallate is prepared by reacting an excess of highly divided lithium hydride powder and an ethereal solution of gallium trichloride:
- GaCl3 + 4 LiH → LiGaH4 + 3 LiCl
The reactants are mixed together at -80 °C and then allowed to get to room temperature. Higher yields (80-95%) and reaction rates are possible by using gallium tribromide.
Properties[edit]
Lithium tetrahydrogallate is easaily dissolved in diethyl ether with which it forms a so stable complex that the complete removal of the solvent is very difficult. Ethereal solutions of LiGaH4 are indefinitely stable if sealed in glass vessels at 0 °C. Lithium tetrahydrogallate can also be dissolved in tetrahydrofuran and diglyme[2].
Lithium tetrahydrogallate slowly decomposes at room temperature. The decomposition is fast at 70 °C and the reaction produces lithium hydride, gaseous hydrogen and metallic gallium[3]. The reaction is autocatalyzed by the small particles of metallic gallium being formed.
Reactivity[edit]
It can be generally stated that lithium tetrahydrogallate's reactivity is similar to lithium tetrahydroalluminate's reactivity, but the first is less stable[4]. Lithium tetrahydrogallate violently reacts with water by releasing 4 moles of gaseous hydrogen.
Ethereal solutions of LiGaH4 are strongly reductant but less than LiBH4 and LiAlH4. It reacts with primary and secondary ammines to release gaseous hydrogen. LiGaH4 reduces acetamide and acetonitrile to ethylamine. Alifatic acids, aldehydes and ketones are reduced to the corresponding alcohols. Aromatic nitriles, aldehydes, ketones and esters are not reduced.
Note[edit]
- ^ N. N. Greenwood et alter (1968). Cambridge University Press (ed.). New Pathways in Inorganic Chemistry.
- ^ T. N. Dymova; Yu. M. Dergachev (December 1973). "Solubility of rubidium tetrahydrogallate in diglyme". Bulletin of the Academy of Sciences of the USSR Division of Chemical Science. 22 (12): 2597–2599. doi:10.1007/BF00926118.
- ^ P. Claudy; J. Bouix (1970). Bulletin de la Société Chimique de France: 1302.
{{cite journal}}: Missing or empty|title=(help) - ^ M. J. Pitt; L. A. Battle (2016). P. G. Urben (ed.). Bretherick's Handbook of Reactive Chemical Hazards. Vol. 1 (5 ed.). Oxford: Elsevier. p. 1452.
See also[edit]
- Sodium tetrahydridogallate
- Potassium tetrahydridogallate
- Cesium tetrahydridogallate
- Lithium tetrahydridoaluminate
[[Category:Gallium compounds]] [[Category:Lithium compounds]] [[Category:Hydrides]]