Process for the preparation of phenylene-bis-benzimidazole-tetrasulphonic acid disodium salt
CA 2430274 A1 · Owner: Koch, Oskar · Inventors: Koch, Oskar; Reinders, Gerald; Bertram, Ralf
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention relates to a method for producing a phenylene-bis-benzimidazoletetrasulfonic acid disodium salt which is largely free from impurities. Said method involves reacting o-phenylene diamine with terephthalic acid and chlorosulfonic acid in the presence of strong acids with a reaction time of , 10 to 15 hours.
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 21, 2001. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 21, 2021.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 21, 2023.
- 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.