Process for the preparation of 2,5-di (phenylamino)terephthalic acid and dialkyl esters thereof in high purity
CA 2076608 A1 · Owner: Ritter, Eberhard · Inventors: Schaefer, Hans; Vollheim, Thomas; Schottler, Martin
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Abstract of the disclosure Process for the preparation of 2,5-di(phenylamino)terephthalic acid and dialkyl esters thereof in high purity, The invention relates to a process for the preparation of dialkyl 2,5-di(phenylamino)terephthalates of the formula (I), (I), in which R is a hydrogen atom or a methyl group and R' is a methyl group or ethyl group, by dehydrogenation (oxidation) of the corresponding dialkyl 2,5-di(phenylamino)- 3,6-dihydroterephthalate with oxygen, which comprises blanketing with oxygen a solution or suspension of the dialkyl 2,5-di(phenylamino)-3,6-dihydroterephthalate in aromatic hydrocarbons in a stirred vessel circulating, this reaction mixture via a spraying device so …
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 August 21, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended August 21, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 21, 2014.
- 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.