Method for purifying chloromethyl chloroformate
View Patent ↗Describes a method for obtaining substantially pure chloromethyl chloroformate from a chloroformate mixture comprising chloromethyl chloroformate and methyl chloroformate by heating the chloroformate mixture in a reaction zone at temperatures ranging from at least 50° C. to the reflux temperature of the chloroformate mixture in the reaction zone while simultaneously removing volatile gaseous decomposition products from the reaction zone. Dichloromethyl chloroformate may also be present in the chloroformate mixture.
1. A method of removing methyl chloroformate from a chloroformate mixture comprising chloromethyl chloroformate and a contaminating amount of methyl chloroformate, which method comprises (a) heating said mixture in a reaction zone in the presence of a catalytic amount of nucleophilic catalyst, (b) simultaneously removing volatile gaseous products resulting from step (a) from said reaction zone, and (c) recovering chloromethyl chloroformate substantially free of methyl chloroformate from said reaction zone.
2. The method of claim 1 wherein the chloroformate mixture further comprises dichloromethyl chloroformate.
3. The method of claim 1 wherein the temperature at which the chloroformate mixture is heated ranges from at least 50° C. to the reflux temperature of the mixture in the reaction zone.
4. The method of claim 3 wherein chemically inert gas is introduced into the reaction zone to assist in the removal of the volatile gaseous products from said reaction zone.
5. The method of claim 1 wherein the reaction zone is maintained at sub-atmospheric pressures during steps (a) and (b).
6. The method of claim 5 wherein the sub-atmospheric pressure ranges from 50 Torr to 720 Torr.
7. The method of claim 4 wherein the reaction zone is maintained at sub-atmospheric pressures during steps (a) and (b).
8. The method of claim 7 wherein the sub-atmospheric pressure ranges from 50 Torr to 720 Torr.
9. The method of claim 1 wherein the nucleophilic catalyst is selected from quaternary ammonium salts, quaternary phosphonium salts, and crown ether, cryptand, spherand or calixarene complexes of organic or inorganic salts.
10. The method of claim 1 wherein the catalyst is a quaternary ammonium or phosphonium salt.
11. The method of claim 10 wherein the catalyst is represented by the following general formulae:
wherein R 1 , R 2 , R 3 and R 4 are each monovalent hydrocarbon groups containing from 1 to 25 carbon atoms, and X is a monovalent anion.
12. The method of claim 11 wherein the total number of carbon atoms in the monovalent hydrocarbon groups ranges from 12 to 35, and the monovalent anion is selected from a halide anion, hydrogen sulfate anion, hydroxyl anion, dihydrogen phosphate anion, and hydrogen phosphate anion.
13. The method of claim 12 wherein the halide anion is a chloride or bromide.
14. The method of claim 4 wherein inert gas introduced into the reaction zone comprises nitrogen.
15. A method for recovering chloromethyl chloroformate from a chloroformate mixture comprising chloromethyl chloroformate, methyl chloroformate and dichloromethyl chloroformate, which method comprises heating said chloroformate mixture in a reaction zone in the presence of a catalytic amount of nucleophilic catalyst, (b) simultaneously removing volatile gaseous products produced in step (a) from said reaction zone, and (c) recovering chloromethyl chloroformate product substantially free of methyl chloroformate and dichloromethyl chloroformate.
16. The method of claim 15 wherein the chloroformate mixture further comprises trichloromethyl chloroformate.
17. The method of claim 15 wherein the chloroformate mixture is heated at temperatures of from greater than 70° C. to the reflux temperature of the mixture in the reaction zone.
18. The method of claim 15 wherein the chloroformate mixture is heated at temperatures of from 86° C. to 100° C.
19. The method of claim 17 wherein chemically inert gas is introduced into the reaction zone to assist in the removal of volatile gaseous products from said reaction zone.
20. The method of claim 19 wherein the volatile gaseous products include hydrogen chloride and the inert gas comprises nitrogen.
21. The method of claim 15 wherein the chloromethyl chloroformate product comprises at least 95% chloromethyl chloroformate, less than 5% methyl chloroformate and less than 2% dichloromethyl chloroformate, as determined by gas chromatography analysis.
22. The method of claim 15 wherein the chloromethyl chloroformate product comprises at least 98% chloromethyl chloroformate, less than 1% methyl chloroformate and less than 1% dichloromethyl chloroformate, as determined by gas chromatography analysis.
23. The method of claim 17 wherein the reaction zone is maintained at sub-atmospheric pressures during steps (a) and (b).
24. The method of claim 17 wherein the catalyst is a quaternary ammonium or phosphonium salt.
25. The method of claim 24 wherein the salt is a chloride or bromide salt.
26. A method comprising the steps of (a) heating a chloroformate mixture comprising chloromethyl chloroformate and contaminating amounts of methyl chloroformate in a reaction zone at temperatures of from at least 50° C. to the reflux temperature of the mixture in the reaction zone in the presence of a catalytic amount of nucleophilic catalyst, (b) simultaneously removing volatile gaseous products including hydrogen chloride resulting from step (a) from said reaction zone, and (c) recovering chloromethyl chloroformate product substantially free of methyl chloroformate from said reaction zone.
27. The method of claim 26 wherein the chloroformate mixture further comprises contaminating amounts of dichloromethyl chloroformate, and the chloromethyl chloroformate product is substantially free of dichloromethyl chloroformate.
28. The method of claim 26 wherein the nucleophilic catalyst is a quaternary ammonium or phosphonium salt.
29. The method of claim 27 wherein the nucleophilic catalyst is represented by the following general formulae:
wherein R 1 , R 2 , R 3 and R 4 are each monovalent hydrocarbon groups containing from 1 to 25 carbon atoms, and X is a monovalent anion.
30. The method of claim 29 wherein the total number of carbon atoms in the monovalent hydrocarbon groups ranges from 12 to 35, and the monovalent anion is selected from a halide anion, hydrogen sulfate anion, hydroxyl anion, dihydrogen phosphate anion, and hydrogen phosphate anion.
31. The method of claim 30 wherein the halide anion is a chloride or bromide.
32. The method of claim 29 wherein chemically inert gas is introduced into the reaction zone to assist in the removal of the volatile gaseous products.
33. The method of claim 29 wherein the reaction zone is maintained at sub-atmospheric pressures during steps (a) and (b).
34. The method of claim 32 wherein the inert gas comprises nitrogen.
35. The method of claim 34 wherein the inert gas is introduced directly into the chloroformate mixture.
36. The method of claim 29 wherein the chloromethyl chloroformate product comprises at least 98% chloromethyl chloroformate, less than 1% methyl chloroformate and less than 1% dichloromethyl chloroformate, as determined by gas chromatography analysis.
37. The method of claim 1 wherein the nucleophilic catalyst is selected from tertiary amines, amides, substituted ureas and thioureas, tertiary phosphines and substituted phosphoramides.
38. The method of claim 37 wherein the nucleophilic catalyst is selected from triethylamine, tributyl amine, pyridine, N,N-dimethylaniline, imidazole, dimethylformamide, tetrabutylurea, tetrabutylthiourea, trioctylphosphine, and hexamethylphosphotriamide.
39. The method of claim 15 wherein the nucleophilic catalyst is selected from tertiary amines, amides, substituted ureas and thioureas, tertiary phosphines and substituted phosphoramides.
40. The method of claim 39 wherein the nucleophilic catalyst is selected from triethylamine, tributyl amine, pyridine, N,N-dimethylaniline, imidazole, dimethylformamide, tetrabutylurea, tetrabutylthiourea, trioctylphosphine, and hexamethylphosphotriamide.
41. The method of claim 26 wherein the nucleophilic catalyst is selected from tertiary amines, amides, substituted ureas and thioureas, tertiary phosphines and substituted phosphoramides.
42. The method of claim 41 wherein the nucleophilic catalyst is selected from triethylamine, tributyl amine, pyridine, N,N-dimethylaniline, imidazole, dimethylformamide, tetrabutylurea, tetrabutylthiourea, trioctylphosphine, and hexamethylphosphotriamide.
43. The method of claim 1 wherein the nucleophilic catalyst is selected from alkyl substituted guanidines and hexasubstituted guanidinium halides.
44. The method of claim 43 wherein the nucleophilic catalyst is selected from tetrabutyl guanidine, pentabutyl guanidine, pentabutyl guanidine hydrogen chloride salt, hexaethyl guanidinium chloride and hexabutylguanidinium chloride.
45. The method of claim 15 wherein the nucleophilic catalyst is selected from alkyl substituted guanidines and hexasubstituted guanidinium halides.
46. The method of claim 45 wherein the nucleophilic catalyst is selected from tetrabutyl guanidine, pentabutyl guanidine, pentabutyl guanidine hydrogen chloride salt, hexaethyl guanidinium chloride and hexabutylguanidinium chloride.
47. The method of claim 26 wherein the nucleophilic catalyst is selected from alkyl substituted guanidines and hexasubstituted guanidinium halides.
48. The method of claim 47 wherein the nucleophilic catalyst is selected from tetrabutyl guanidine, pentabutyl guanidine, pentabutyl guanidine hydrogen chloride salt, hexaethyl guanidinium chloride and hexabutylguanidinium chloride.