Granted Patent
Utility
US 5,200,556 · App. 07/887,182
Process for the preparation of 3,4,6-trifluorophthalic acid and the anhydride thereof
Inventors:
Theodor Papenfuhs, Ralf Pfirmann
Patented Case
View Patent ↗
Granted: Apr 6, 1993
Filed: May 21, 1992
Inventors
Theodor Papenfuhs
Ralf Pfirmann
Assignee (at issue)
Hoechst GmbH
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.