A process for the preparation of highly pure aromatic diurethanes and/or polyurethanes
CA 2085284 A1 · Owner: Friederichs, Wolfgang · Inventors: Wershofen, Stefan; Friederichs, Wolfgang; Penninger, Stefan
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Mo3814, LeA 28,779, A PROCESS FOR THE PREPARATION OF HIGHLY PURE AROMATIC DIURETHANES AND/OR POLYURETHANES ABSTRACT OF THE DISCLOSURE, This invention relates to a process for the preparation of highly pure aromatic diurethanes and/or polyurethanes by reaction of the corresponding aromatic diamines and/or polyamines with unsubstituted carbamates with the release of ammonia. The reaction is carried out in the presence of excess carbamates. The resultant reaction mixture is freed from any solvents used, and the formed aromatic diurethanes and/or polyurethanes are purified by extraction with water.
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 December 14, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended December 14, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 14, 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.