3-hydroxy-2-cyclobuten-1-one salts, their production and use
CA 2036808 C · Owner: Scholl, Thomas · Inventors: Scholl, Thomas; Jackson, Barry
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Novel 3-hydroxy-2-cyclobuten-1-one salts are disclosed of the general formula:, (see formula I) wherein R is an alkali metal atom or an ammonium group of the general formula:, (see fig II), wherein R1 R2 and R3 are the same or different in meaning and each is a hydrogen atom, a lower alkyl group or a cycloalkyl group. The salts of formula I are obtained by the reaction of 3-acetoxy-2-cyclobuten-1-one 1,3-cyclobutanedione or a distillation residue of diketene production containing 3-acetoxy-2-cyclobuten-1-one with a, base. The base can be an amine of the general formula: wherein R1, R2 and R3 have the above-mentioned meaning or, an alkali metal alcoholate or an alkali metal hydroxide. The …
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 February 21, 1991 and granted May 23, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 21, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 21, 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.