Claims
- 1. A process for preparing 2,3,5-trichloropyridine, comprising:
- reacting 2,3,5,6-tetrachloropyridine in a reaction medium including zinc, an aqueous alkaline reagent, a water-immiscible organic solvent, and a phase transfer catalyst to form 2,3,5-trichloropyridine.
- 2. The process of claim 1, wherein the phase transfer catalyst includes a cation of the formula: ##STR6## wherein: R.sub.6, R.sub.7, and R.sub.8, which may be the same as one another or may differ, are H; C.sub.1 to C.sub.6 alkyl, and wherein two of R.sub.6, R.sub.7 and R.sub.8 may together as alkyl groups form a ring; C.sub.1 to C.sub.6 alkenyl; alkyl-phenyl, wherein the alkyl is C.sub.1 to C.sub.6 and the phenyl is optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy; or phenyl, optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy; and
- R.sub.9 is C.sub.1 to C.sub.6 alkyl; C.sub.1 to C.sub.6 alkenyl; alkyl-phenyl, wherein the alkyl is C.sub.1 to C.sub.6 and the phenyl is optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy; or phenyl, optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy.
- 3. The process of claim 1, wherein the aqueous alkaline reagent is an aqueous alkali or alkaline earth metal hydroxide, or aqueous ammonium hydroxide.
- 4. The process of claim 1, wherein the water-immiscible organic solvent is an aromatic solvent.
- 5. The process of claim 4 wherein the aromatic solvent is benzene or an alkylbenzene solvent.
- 6. The process of claim 5 wherein the aromatic solvent is toluene.
- 7. The process of claim 5 wherein the aromatic solvent is ortho-xylene.
- 8. The process of claim 1, wherein said zinc is included in a ratio of at least about 0.5 gram atoms per mole of said 2,3,4,5-tetrachloropyridine.
- 9. The process of claim 8, wherein said zinc is included in a ratio of about 0.5 to about 3 gram atoms per mole of said 2,3,4,5-tetrachloropyridine.
- 10. The process of claim 2, wherein R.sub.6, R.sub.7, and R.sub.8 are each C.sub.1 to C.sub.6 alkyl; C.sub.1 to C.sub.6 alkenyl; alkyl-phenyl, wherein the alkyl is C.sub.1 to C.sub.6 and the phenyl is optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy; or phenyl, optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy.
- 11. The process of claim 10, wherein R.sub.6, R.sub.7, R.sub.8, and R.sub.9 are C.sub.1 to C.sub.6 alkyl.
- 12. The process of claim 11, wherein R.sub.6, R.sub.7, R.sub.8, and R.sub.9 are each methyl.
- 13. The process of claim 11, wherein said dechlorinating is conducted at a temperature in the range of about 10.degree. C. to about 100.degree. C.
- 14. The process of claim 1, wherein said phase transfer catalyst is present in an amount of about 0.01 mole % to about 30 mole % relative to said 2,3,5,6-tetrachloropyridine.
- 15. The process of claim 14, wherein said aqueous alkaline reagent is aqueous sodium hydroxide.
- 16. The process of claim 15, wherein said aqueous alkaline reagent is about 10% w/w to about 40% w/w aqueous sodium hydroxide.
- 17. The process of claim 1, wherein said reacting is conducted under adiabatic temperature conditions.
- 18. The process of claim 1, wherein said dechlorinating is conducted under isothermal temperature conditions.
- 19. The process of claim 1, wherein said zinc, phase transfer catalyst, or aqueous alkaline reagent is added to said reaction mixture in multiple doses over the course of said reacting.
- 20. A process for dechlorinating a chlorinated pyridine compound, comprising:
- dechlorinating a chlorinated pyridine compound in a reaction medium including zinc, an aqueous alkaline reagent, a water-immiscible organic solvent, and a catalytic amount of a phase transfer catalyst.
- 21. The process of claim 20, wherein the phase transfer catalyst has a cation of the formula: ##STR7## wherein: R.sub.6, R.sub.7, and R.sub.8, which may be the same as one another or may differ, are H; C.sub.1 to C.sub.6 alkyl, and wherein two of R.sub.6, R.sub.7 and R.sub.8 may together as alkyl groups form a ring; C.sub.1 to C.sub.6 alkenyl; alkyl-phenyl, wherein the alkyl is C.sub.1 to C.sub.6 and the phenyl is optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy; or phenyl, optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy; and
- R.sub.9 is C.sub.1 to C.sub.6 alkyl; C.sub.1 to C.sub.6 alkenyl; alkyl-phenyl, wherein the alkyl is C.sub.1 to C.sub.6 and the phenyl is optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy; or phenyl, optionally substituted with C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 alkenyl, halogen, hydroxyl, or C.sub.1 to C.sub.6 alkoxy.
- 22. The process of claim 20 or 21, which comprises dechlorinating 2,3,5,6-tetrachloropyridine to form 2,3,5-trichloropyridine.
- 23. The process of claim 20 or 21, which comprises dechlorinating 2,3,4,5-tetrachloropyridine to form 2,3,5-trichloropyridine.
- 24. The process of claim 20 or 21, which comprises dechlorinating 2,3,4,5,6-pentachloropyridine to form 2,3,5,6-tetrachloropyridine.
- 25. The process of claim 20 or 21, which comprises dechlorinating 2,3,4,5,6-pentachloropyridine to form 2,3,5-trichloropyridine.
- 26. The process of claim 20 or 21, which comprises dechlorinating 2,3,4,5,6-pentachloropyridine to form 2,5-dichloropyridine.
- 27. The process of claim 20 or 21, which comprises dechlorinating 2,3,5,6-tetrachloropyridine to form 2,5-dichloropyridine.
- 28. The process of claim 20 or 21, which comprises dechlorinating 2,3,4,5-tetrachloropyridine to form 2,5-dichloropyridine.
- 29. A dechlorination process, comprising dechlorinating a pyridine compound of the formula: ##STR8## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 are H, chloro, or a C.sub.1 to C.sub.20 hydrocarbon group, with the proviso that at least one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 is chloro, in the presence of zinc, an aqueous alkaline reagent, a water-immiscible organic solvent, and a catalytic amount of a phase transfer catalyst.
- 30. The process of claim 26, wherein said dechlorinating is conducted with about 0.01 mole % to about 30 mole % of said phase transfer catalyst relative to said pyridine compound.
- 31. The process of claim 27, wherein said water-immiscible organic solvent is an inert aromatic solvent or inert aliphatic solvent.
- 32. The process of claim 28, wherein said pyridine compound is selected from the group consisting of 2,3,4,5,6-pentachloropyridine, 2,3,5,6-tetrachloropyridine, and 2,3,4,5-tetrachloropyridine.
- 33. The process of claim 29, wherein said pyridine compound is 2,3,5,6-tetrachloropyridine.
REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. provisional patent application Ser. No. 60/077,816 filed Mar. 12, 1998, which is hereby incorporated by reference herein in its entirety.
US Referenced Citations (8)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0012117 |
Dec 1979 |
EPX |