The preparation of 3-methylpyrazole
CA 2048456 C · Owner: Merkle, Hans Rupert · Inventors: Fretschner, Erich; Merkle, Hans Rupert
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
3-Methylpyrazole and its derivatives are prepared by reacting butenediols or ethynylalkylcarbinolg or their acylates in 30-100% by weight sulfuric acid with unsubstituted or substituted hydrazine or its salts in the presence of catalytic amounts of iodine or an iodine compound.
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 6, 1991 and granted July 10, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 6, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 6, 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.