Preparation of a para-aminodiphenylamine
CA 2024686 C · Owner: Cottman, Kirkwood Storer · Inventors: Cottman, Kirkwood Storer
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention relates to a process for the preparation of a p-aminodiphenylamine comprising reacting N-phenylquinoneimine of the formula: (see fig. I), with ammonia, ammonium hydroxide or mixtures thereof wherein the molar ratio of N-phenylquinoneimine to NH3 in the reaction mixture ranges from about 1:1 to 1:80.
Read 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
- Filed September 5, 1990 and granted August 17, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 5, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 5, 2012.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
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.