METHOD FOR PREPARATION OF CRYSTALLINE ALANE USING QUARTERNARY AMMONIUM ALUMINUM HYDRIDE
The invention relates to a method of forming α-alane. The method includes reacting a tetraalkyl ammonium alanate solution in toluene with an alkyl halide or other proton source such as HCl or H 2 SO 4 .
1 . A method of producing α-alane comprising:
preparing a tetraalkyl ammonium alanate solution in toluene;
heating the solution while adding an alkyl halide to produce crystals for nucleation; after producing the crystals for nucleation, slowly adding alkyl halide to produce alane, toluene, and tetraalkyl ammonium chloride;
continuing to heat the solution so that the alane that is formed is in the α-crystalline phase; and,
removing the α-alane crystals by filtration, leaving tetraalkyl ammonium halide in toluene solution as the filtrate.
2 . The method of claim 1 , wherein sufficient alkyl halide is added to make the solution 0.005 M.
3 . The method of claim 1 , wherein the tetraalkyl ammonium alanate solution in toluene is prepared by the metathesis of a tetraalkyl ammonium halide and an alkali metal alanate in a toluene solution.
4 . The method of claim 1 , wherein the alkali metal halide is filtered from the solution.
5 . The method of claim 1 , wherein the alkali metal halide is sodium halide.
6 . The method of claim 1 , wherein the alkali metal halide is lithium halide.
7 . The method of claim 1 , wherein the method is continuous and the filtrate is used to create the tetraalkyl ammonium alanate solution in toluene by the addition of a alkali metal alanate.
8 . The method of claim 1 , wherein the crystallizing the α-alane comprises heating the solution to a temperature range from 50° to 95° C.
9 . The method of claim 8 , wherein the temperature range is from 60° to 65° C.
10 . The method of claim 8 , wherein the temperature range is from 65° to 87° C.
11 . The method of claim 8 , wherein the temperature range is from 88° to 95° C.
12 . The method of claim 8 , wherein the temperature range is from 50° to 60° C.
13 . A method of producing α-alane comprising:
preparing a tetraalkyl ammonium alanate solution in toluene;
adding sufficient tetrahydrofuran to produce alane, toluene, and a tetraalkyl ammonium compound; and,
removing the α-alane crystals by filtration, leaving tetraalkyl ammonium halide in toluene solution as the filtrate.
14 . The method of claim 13 , wherein the tetraalkyl ammonium alanate solution in toluene is prepared by the metathesis of a tetraalkyl ammonium halide and an alkali metal alanate in a toluene solution.
15 . The method of claim 13 , wherein the alkali metal halide is filtered from the solution.
16 . The method of claim 13 , wherein the alkali metal halide is sodium halide.
17 . The method of claim 13 , wherein the alkali metal halide is lithium halide.
18 . The method of claim 13 , wherein the method is continuous and the filtrate is used to create the tetraalkyl ammonium alanate solution in toluene by the addition of a alkali metal alanate.
19 . The method of claim 13 , wherein the crystallizing the α-alane comprises heating the solution to a temperature range from 50° to 95° C.
20 . The method of claim 19 wherein the temperature range is from 60° to 65° C.
21 . The method of claim 19 wherein the temperature range is from 65° to 87° C.
22 . The method of claim 19 wherein the temperature range is from 88° to 95° C.
23 . The method of claim 19 wherein the temperature range is from 50° to 60° C.