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:
Jan. 11, 2000
Filed:
Apr. 15, 1999
Philip D Hammen, East Haddam, CT (US);
Peter R Rose, Ledyard, CT (US);
John L Tucker, Niantic, CT (US);
Keith M Devries, Chester, CT (US);
Diane M Rescek, Oakdale, CT (US);
Pfizer Inc., New York, NY (US);
Abstract
A process of purifying a (6-chloro-2-carbazolyl)methyl-malonic acid di(C.sub.1 -C.sub.6 alkyl) ester of Formula (I): ##STR1## wherein R.sub.a and R.sub.b must be the same and are selected from the group consisting of C.sub.1 -C.sub.6 alkyl; comprises phase separating one or more impurities from said carbazole ester at least once wherein the solvent used to carry out said phase separation is acetic acid. In a preferred embodiment said acetic acid is glacial acetic acid which is maintained at a temperature of from about 30.degree. to about 110.degree.0 C. and said carbazole ester is obtained in a purity of at least 99.90% by weight, so that the amount of impurities present therein is 0.10% or less by weight. In a more preferred embodiment of said process, said temperature is from about 50.degree. to about 70.degree. C., and said phase separation is carried out only once.