Preparation of relatively pure p, p-bisphenol s
CA 2066178 A1 · Owner: Aristech Chemical Corporation · Inventors: Mulhall, Steven E.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process of preparing 4,4'-Bisphenol S wherein sulfuric acid is reacted with an excess of phenol while removing water; the product purity is improved with respect to the 2,4'-BPS isomer by adding toluene to the initial product mixture to crystallize and remove the desired 4,4'-BPS. The remaining material is recycled to isomerize the 2,4'-BPS to 4,4'-BPS.
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 June 24, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended June 24, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 24, 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.