Process for the preparation of 3,4,6-trifluorophthalic acid and the anhydride thereof
CA 2069140 A1 · Owner: Hoechst Aktiengesellschaft · Inventors: Papenfuhs, Theodor; Pfirmann, Ralf
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Process for the preparation of 3,4,6-tetrafluorophthalic acid and the anhydride thereof, Process for the preparation of 3,4,6-tetrafluorophthalic acid of the formula (1), ( 1 ), or the anhydride thereof in good yields and in an advantageous manner, by dehalogenating tetrafluorophthalic anhydride of the formula (2), (2) or tetrafluorophthalic acid in aqueous-alkaline medium using zinc at temperatures of approximately 20°C to approximately 160°C and, if appropriate converting the, resulting 3,4,6-trifluorophthalic acid into the anhydride in a known manner by dehydrating it.
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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 May 21, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended May 21, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 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.