Process for the preparation of 4-alkylsulfonyl-1-alkyl-2-chlorobenzenes and the like
CA 2104116 C · Owner: Hoechst Aktiengesellschaft · Inventors: Papenfuhs, Theodor; Folz, Georg
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Process for the preparation of 4-alkylsulfonyl-1alkyl-2-chlorobenzenes and like compounds. A process for the preparation of 4-alkyl(C1-C4)sulfonyl-1-alkyl-2-chlorobenzenes, in very good yields and with high selectivity by selectively chlorinating a p-alkyl-benzenesulfonyl chloride with gaseous chlorine in the presence of a chlorine carrier at 50°C to 100°C to give a compound of the formula, (see formula I) in which R1 is an alkyl(C1-C4) group, subsequently reducing the latter in an aqueous medium at a pH of 8 to 10 with alkali metal sulfate or alkali metal hydrogen sulfite preferably sodium hydrogen sulfite or sodium sulfite at 40, to 90°C to give a compound of the formula (see formula …
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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 January 31, 1992 and granted December 12, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 31, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 31, 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
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Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.