Granted Patent
Utility
US 4,267,392 · App. 06/053,532
Process for obtaining para-cresol and meta-cresol from a mixture of methylated and ethylated phenols containing meta-para-cresol
Inventor:
Gerd Leston
Patented Case
View Patent ↗
Granted: May 12, 1981
Filed: Jun 29, 1979
Inventor
Gerd Leston
Assignee (at issue)
KOPPERS, INC.
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.