Preparation of phthalic anhydride from o-xylene
CA 2040981 A1 · Owner: Aichinger, Heinrich · Inventors: Seubert, Rolf; Ruppel, Wilhelm; Schmidt, Johannes E.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
BASFAKTIENQESELLSCHAFT O.Z.0050/41580, Preparation of phthalic anhydride from o-xylene Abstract of the disclosure:, Phthalic anhydride is prepared in a multiple tube reactor provided withseparate salt baths the temperature of the salt bath used for cooling the first layer of catalyst, as regarded in the direction of flow of the reaction mixture, being from 2° to 20°C higher than that of the salt bath(s) associated with the following layer(s).
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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 April 23, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended April 23, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 23, 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.