Process for the preparation of water-soluble azo dyestuffs
CA 1063598 A · Owner: Hoechst Aktiengesellschaft · Inventors: Landler, Josef; Worfel, Erhard
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A new and very advantageous process had been found for the preparation of azo dyestuffs by diazotation and coupling in which the synthesis is carried out without the hitherto usual addition of an acid, with the proviso that at least one of the diazo and coupling components contains at least one acid group. Besides the saving of reaction material and subsequently of alkali for neutralization of the reaction medium and isolation of the dyestuff, highly concentrated solutions of the dyestuff and salt-free or practically salt-free dyestuffs ran be obtained, and waste-water is no longer charged with big amounts of salts.
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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
- Granted October 2, 1979. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended October 2, 1996.
- 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.