Granted Patent
Utility
US 4,251,675 · App. 06/021,043
Preparation of diphenylmethane
Inventor:
Dusan J. Engel
Patented Case
View Patent ↗
Granted: Feb 17, 1981
Filed: Mar 15, 1979
Inventor
Dusan J. Engel
Assignee (at issue)
UOP LLC
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.