Granted Patent
Utility
US 4,889,955 · App. 07/270,819
Preparation of (hydrocarbylthio)aromatic amines
Inventor:
Paul F. Ranken
Patented Case
View Patent ↗
Granted: Dec 26, 1989
Filed: Nov 14, 1988
Inventor
Paul F. Ranken
Assignee (at issue)
Ethyl Corporation
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.