Process for the preparation of 2,3-difluoro-5-halopyridines

Details Process for the preparation of 2,3-difluoro-5-halopyridines Process for the preparation of 2,3-difluoro-5-halopyridines

1994-11-01

1997-07-22

Ivy, C. Warren

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C07D21361

Patent

active

056505175

ABSTRACT:
2,3-Difluoro-5-halopyridines of the formula I ##STR1## wherein X is Cl or Br are prepared by a process which comprises reacting a starting 2,3,5-trihalopyridine of the formula II ##STR2## wherein each X is individually Br or Cl and Y is F, Cl or Br with an effective amount of potassium fluoride in the presence of a mixture of sulfolane and a tetralkylurea and/or a dialkyl-alkyleneurea as diluent, at an effective temperature up to the boiling point of the diluent, optionally in the presence of a phase-transfer catalyst such as a crown ether or polyglycol ether. The compounds are useful as intermediates to prepare herbicides.

REFERENCES:
patent: 4031100 (1977-06-01), Giacobbe
patent: 4071521 (1978-01-01), Muench
patent: 4565568 (1986-01-01), Johnston et al.
patent: 4713109 (1987-12-01), Schurter et al.
patent: 4822887 (1989-04-01), Little
Patent Abstracts of Japan, vol. 95 No. 1, 28, 1995 of JP-A-06-298734 (1994).
G. C. Finger et al., J. Organ. Chem., vol. 28, pp. 1666-1668 (1963).

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