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:
Oct. 07, 1997
Filed:
Nov. 16, 1994
Lalitha Krishnan, Suffern, NY (US);
Richard A Leese, Suffern, NY (US);
Raghavan Krishnan, Suffern, NY (US);
American Cyanamid Company, Madison, NJ (US);
Abstract
The invention provides a method for selectively extracting a compound of formula I: ##STR1## wherein: R is hydrogen or --NR.sub.3 R.sub.4 ; and when R=--NR.sub.3 R.sub.4, R.sub.3 and R.sub.4 may be the same or different and are selected from hydrogen and straight or branched (C.sub.1 -C.sub.4)alkyl; R.sub.1 and R.sub.2 may be the same or different and are selected from straight or branched (C.sub.1 -C.sub.6)alkyl; from an aqueous mixture containing a compound of Formula I, its C-4 epimer and its oxidative degradation by-products by adding methylene at a concentration of 2-4 ml of methylene chloride per gram of compound of Formula I and at a pH between pH 6.5-8.0; and obtaining an extract containing methylene chloride, a compound of Formula I, and its C-4 epimer, said epimer being present in an amount of less than 3% of the amount of the compound of Formula I.