Preparation of tri-alkyl gallium or tri-alkyl indium compounds
View Patent ↗Trialkyl metal compounds, such as trialkyl gallium and indium compounds, are prepared in high yield and high purity by the addition of a trialkyl aluminum compound to a mixture prepared by adding a metal trihalide, e.g., GaCl 3 or InCl 3 , and a halide salt of a monovalent metal to an ionic liquid such as a molten salt of the formula M[AlR n X (4-n) ] wherein M is a monovalent metal such as Li, Na, K or Cs, R is an alkyl group X is a halide and n is a number from 1 to 3, typically at temperatures of from 75 to 160° C.
1. A method for preparing trialkyl metal compounds of the formula GaR 3 or InR 3 comprising:
a) adding GaX 3 or InX 3 and monovalent salt MX to an ionic liquid comprising one or more than one molten salt of the formula M[AlR n X (4-n) ] at a temperature of from 75 to 160° C. to form a mixture of salts;
b) adding from 0.9 to 2.0 molar equivalents of AlR 3 , based on moles of GaX 3 or InX 3 , to the mixture of salts formed in a) to form a reaction mixture, and
c) distilling GaR 3 or InR 3 from the reaction mixture;
wherein each M is independently Li, Na, K or Cs; each X is independently is F, Cl, Br or I; R is C 1-6 alkyl; n is a number of from 1 to 3; and wherein the amount of MX added is 1.0 to 2.0 molar equivalents of the amount of added GaX 3 or InX 3 .
2. The method according to claim 1 wherein R is C 1-4 alkyl.
3. The method according to claim 1 wherein R is methyl or ethyl.
4. The method according to claim 1 wherein M is Li, Na or K.
5. The method according to claim 1 wherein 1.0 to 1.7 molar equivalents of AlR 3 , based on moles of GaX 3 or InX 3 is added in b).
6. The method according to claim 5 wherein 1.2 to 1.6 molar equivalents of AlR 3 based on moles of GaX 3 or InX 3 is added in b).
7. The method according to claim 1 further comprising performing additional sequences of a), b) and c), wherein the compound of formula GaR 3 or InR 3 isolated during each sequence is combined and optionally further purified.
8. The method according to claim 1 wherein isolated GaR 3 or InR 3 is purified by distillation from a mixture containing a fluoride salt.
9. The method according to claim 5 wherein 1.0 to 1.7 molar equivalents of MX based on moles of GaX 3 or InX 3 is added in a).
10. The method according to claim 6 wherein 1.2 to 1.6 molar equivalents of MX, based on moles of GaX 3 or InX 3 is added in a).
11. The method according to claim 1 wherein M is Li, Na or K; X is CI or Br; and R is methyl or ethyl and each M and each X is the same.
12. The method according to claim 1 wherein vacuum is applied to aid in distillation.
13. The method according to claim 1 wherein the ionic liquid solvent comprising one or more salts of formula M[AlR n X (4-n) ] is first obtained by reacting trialkyl aluminum and trihalo gallium or indium in the presence of a salt MX, or reaction between trialkyl aluminum and a tetrahalo gallium or indium salt in the absence of an organic solvent.
14. The method according to claim 1 wherein a compound of formula GaR 3 is prepared from a compound of formula GaX 3 .
15. The method according to claim 14 wherein isolated GaR 3 is purified by distillation from a mixture containing a fluoride salt.
16. The method according to claim 5 wherein a compound of formula GaR 3 is prepared from a compound of formula GaX 3 .
17. The method according to claim 7 wherein a compound of formula GaR 3 is prepared from a compound of formula GaX 3 .
18. The method according to claim 1 wherein a compound of formula InR 3 is prepared from a compound of formula InX 3 .
19. The method according to claim 5 wherein a compound of formula InR 3 is prepared from a compound of formula InX 3 .
20. The method according to claim 7 wherein a compound of formula InR 3 is prepared from a compound of formula InX 3 .