Verfahren zur herstellung von 2,5-di-phenylamino-terephtalsaure und ihrer dialkylester in hoher reinheit
CA 2096845 A1 · Owner: Arndt, Otto · Inventors: Gilb, Walter; Arndt, Otto; Fuchs, Hermann
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Disclosed is an environmentally and economically improved method for the preparation of 2,5-di(phenylamino)terephthalic acid and its dialkyl esters of general formula (I) in which R is a, hydrogen atom or a methyl group and R' is a hydrogen atom or a methyl or ethyl group.
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 November 2, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 2, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 2, 2013.
- 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.