Process for increasing the direct esterification reaction rate of a diacid with a glycol
CA 2031611 C · Owner: E.I. Du Pont De Nemours And Company · Inventors: Lowe, David J.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for increasing the direct, esterification reaction rate between a diacid and 1,4-butanediol and for directly esterifying greater than 95% of the acid ends of the diacid by mixing in any order the diacid, the 1,4-butanediol and a catalyst compound selected from organo-titanium organo-tin, and organo-zirconium compounds to form a, reaction mixture wherein the ratio of diol:diacid is at least 2:1 and then reacting the reaction mixture at an average temperature ranging between 190°C to 240°C for a period of time no longer than sixty minutes. The same process may be followed substituting ethylene glycol for 1,4-butanediol, provided the catalyst . compound is added neat further provided …
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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 December 5, 1990 and granted May 8, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 5, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 5, 2012.
- 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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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.