Process for the preparation of 2,3-difluoro-6-nitrophenol
CA 2092407 C · Owner: Pfirmann, Ralf · Inventors: Pfirmann, Ralf; Hackenbruch, Joachim; Papenfuhs, Theodor
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
According to a process for producing isomer-free 2,3-difluor-6-nitrophenol, 2,3,4-trifluornitrobenzol is reacted with an aqueous solution of alkali metal or alkaline earth metal hydroxide in the absence of organic solvent at, temperatures between about 20°C and 100°C the pH value of the, reaction mixture is set at about 1 to 6 by acid addition the, resulting product is steam distilled and the 2,3-difluor-6nitrophenol is isolated after cooling. No organic solvents are used during any of the steps of the process.
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 25, 1991 and granted March 18, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 25, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 25, 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.