Preparation of acetalized azo dyes
CA 2071434 C · Owner: Hansen, Guenter · Inventors: Zeidler, Georg; Hansen, Guenter
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Acetalized azo dyes axe prepared by diazotizing an amine, coupling with a hydroxyalkyl-containing coupling component and subsequently reacting with a vinyl ether in a process which comprises carrying out the coupling reaction in a two-phase reaction mixture comprising water and an aromatic hydrocarbon, subsequently separating off the aqueous phase and reacting the azo dye which is present, in the organic phase without intermediate isolation, with a vinyl ether in the presence of a polybasic carboxylic acid as catalyst.
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 17, 1992 and granted September 3, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 17, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 17, 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
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.