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:
Jun. 06, 2000
Filed:
Mar. 12, 1998
Louie Akos Nady, Daphne, AL (US);
Seyed Mehdi Tavana, Daphne, AL (US);
Thomas Gray, Midhurst, GB;
Stephen Martin Brown, Upper Cumberworth, GB;
Brian David Gott, Skilmanthokee, GB;
Zeneca Limited, London, GB;
Abstract
A process for the purification of a compound of general formula I: ##STR1## wherein R.sup.1 is hydrogen or C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl or C.sub.2 -C.sub.6 alkynyl, any of which may optionally be substituted with one or more substituents selected from halogen and hydroxy; or COOR.sup.4, COR.sup.6, CONR.sup.4 R.sup.5 or CONHSO.sub.2 R.sup.4 ; R.sup.4 and R.sup.5 independently represent hydrogen or C.sub.1 -C.sub.4 alkyl optionally substituted with one or more halogen atoms; R.sup.6 is a halogen atom or a group R.sup.4 ; R.sup.2 is hydrogen or halo; and R.sup.3 is C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 alkenyl or C.sub.2 -C.sub.4 alkynyl, any of which may optionally be substituted with one or more halogen atoms; or halo; or, where appropriate, a salt thereof; from a mixture containing the compound of general formula I together with one or more isomers or di-nitrated analogues thereof; the process comprising dissolving the mixture in a suitable crystallisation solvent and recrystallising the product from the resulting crystallisation solution wherein the crystallisation solution contains not more than 25% loading of the compound of general formula I, loading being defined as: ##EQU1## and wherein the temperature to which the solution is cooled for crystallisation is not greater than about 30.degree. C.; wherein, after the addition of the crystallising solvent but before recrystallisation, the crystallisation solution is subjected to at least one wash with an aqueous solution having an acid pH followed by back extraction with fresh crystallising solvent. The process is particularly useful for purifying acifluorfen produced via a route starting with m-cresol.