The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 31, 1981
Filed:
Sep. 10, 1979
Claus D Weis, Pfeffingen, CH;
Ciba-Geigy Corporation, Ardsley, NY (US);
Abstract
A novel process for producing 2,3,5,6-tetrachloropyridine is described. In this process, pentachloropyridine is reacted, in an alkanephosphonic acid dialkyl ester (dialkyl alkane phosphonate) having 1 to 4 carbon atoms in each of the alkyl groups or in a phosphoric acid trialkyl ester (trialkyl phosphate) having 1 to 4 carbon atoms in each of the alkyl groups as the solvent, at 60.degree. to 120.degree. C., in the presence of 1.4 to 2.8 mols, per mol of pentachloropyridine, of an ammonium salt of an inorganic or organic acid, with 1.2 to 1.6 gram atoms of zinc per mol of pentachloropyridine, with selective dechlorination of the pentachloropyridine in the 4-position occurring. 2,3,5,6-Tetrachloropyridine is a valuable commercial product, which can be used for producing insecticidal formulations. Furthermore, 2,3,5,6-tetrachloropyridine is used as intermediate for the production of herbicidally effective .alpha.-[4-(3',5',6'-trichloropyrid-2'-yloxy)-phenoxy]-alkanecarboxylic acids and derivatives thereof. There are also described novel ammonium salts of methanephosphonic acid monomethyl ester, in the presence of which the selective dechlorination of pentachloropyridine in the 4-position can be advantageously performed.