US3947457A
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Method for preparing 2,5-dihalo- and 2,5,6-trihalopyridines
Assignee: Dow Chemical Co
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Filing: 1974-12-27
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Granted: 1976-03-30
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Expires: 1994-12-27
Abstract
Abstract A method for preparing 2,5-dihalo- and 2,5,6-trihalopyridines corresponding to the formula ##SPC1## Wherein each X independently represents chloro, fluoro or bromo and R represents hydrogen, chloro, fluoro or bromo which comprises reacting a halohydrazinopyridine of one of the formulas ##SPC2## With an excess of an aqueous alkali metal hydroxide in the presence of a reaction medium from the group consisting of loweralkanols of 1 to 4 carbon atoms and loweralkylglycols of 2 to 4 carbon atoms.
Inventors
- 👤 Stanley D. McGregor
- 👤 Herman O. Senkbeil
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:17
CPC Classifications
C; C07; C07D; C07D213/00; C07D213/02; C07D213/04; C07D213/60; C07D213/61
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
75 words
A method for preparing 2,5-dihalopyridine corresponding to the formula: ##SPC7## wherein each X independently represents chloro, fluoro or bromo which comprises reacting at a temperature of from about 50°C to the reflux temperature a halohydrazinopyridine of one of the formulas ##SPC8## with an aqueous alkali metal hydroxide in the presence of a reaction medium selected from the group consisting of lower-alkanols of 1 to 4 carbon atoms and loweralkylglycols of 1 to 4 carbon atoms.
Claim 2
Independent Claim
75 words
A method for preparing 2,5-dihalopyridine corresponding to the formula: ##SPC7## wherein each X independently represents chloro, fluoro or bromo which comprises reacting at a temperature of from about 50°C to the reflux temperature a halohydrazinopyridine of one of the formulas ##SPC8## with an aqueous alkali metal hydroxide in the presence of a reaction medium selected from the group consisting of lower-alkanols of 1 to 4 carbon atoms and loweralkylglycols of 1 to 4 carbon atoms.
Claim 3
Dependent Claim
10 words
The method of claim 1 wherein each X represents chloro.
Claim 4
Dependent Claim
10 words
The method of claim 1 wherein each X represents fluoro.
Claim 5
Dependent Claim
10 words
The method of claim 1 wherein each X represents bromo.
Claim 6
Dependent Claim
27 words
The method of claim 1 wherein the halohydrazinopyridine is 2,3,5-trichloro-4-hydrazinopyridine, the alkali metal hydroxide is sodium hydroxide, the reaction medium is ethanol and the 2,5-dihalopyridine is 2,5-dichloropyridine.
Claim 7
Dependent Claim
27 words
The method of claim 1 wherein the halohydrazinopyridine is 3,5,6-trichloro-2-hydrazinopyridine, the alkali metal hydroxide is sodium hydroxide, the reaction medium is ethanol and the 2,5-dihalopyridine is 2,5-dichloropyridine.
Claim 8
Independent Claim
73 words
A method for preparing 2,5,6-trihalopyridine corresponding to the formula: ##SPC9## wherein each X independently represents chloro, fluoro or bromo which comprises reacting at a temperature of from about 50°C to the reflux temperature a halohydrazinopyridine of the formula ##SPC10## with an aqueous alkali metal hydroxide in the presence of a reaction medium selected from the group consisting of loweralkanols of 1 to 4 carbon atoms and loweralkylglycols of 1 to 4 carbon atoms.
Claim 9
Independent Claim
73 words
A method for preparing 2,5,6-trihalopyridine corresponding to the formula: ##SPC9## wherein each X independently represents chloro, fluoro or bromo which comprises reacting at a temperature of from about 50°C to the reflux temperature a halohydrazinopyridine of the formula ##SPC10## with an aqueous alkali metal hydroxide in the presence of a reaction medium selected from the group consisting of loweralkanols of 1 to 4 carbon atoms and loweralkylglycols of 1 to 4 carbon atoms.
Claim 10
Dependent Claim
10 words
The method of claim 7 wherein each X represents chloro.
Claim 11
Dependent Claim
10 words
The method of claim 7 wherein each X represents bromo.
Claim 12
Dependent Claim
10 words
The method of claim 7 wherein each X represents fluoro.
Claim 13
Dependent Claim
27 words
The method of claim 7 wherein the halohydrazinopyridine is tetrachloro-4-hydrazinopyridine, the alkali metal hydroxide is sodium hydroxide, the reaction medium is isopropanol and the 2,5,6-trihalopyridine is 2,5,6-trichloropyridine.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-30 | 1979-09-29 | 1980-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-30 | 1983-09-29 | 1984-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-30 | 1987-09-29 | 1988-03-30 | $7700.00 | Window Closed / Lapsed |