Expired Canadian patentCanada
Esters and amides of 3'-hydroxyquinophthalone-5-carboxylic acid and derivatives thereof
CA 680933 A · Owner: E.I. Du Pont De Nemours And Company · Inventors: John W. Richter
Overview
Drawings and full text
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordRead the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted February 25, 1964. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 25, 1981.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Filed—
GrantedFebruary 25, 1964
Term endedFebruary 25, 1981
Patent numberCA 680933 A
Classification (IPC)C07D
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.