Method and intermediates for preparing 3,3'-azo-bis- (6-hydroxy benzoic acid)
CA 1164861 A · Owner: Nygren, Alf S. · Inventors: Agback, Karl H.; Nygren, Alf S.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process is provided for preparing 3,3'-azo-bis(6-hydroxy benzoic acid) of formula I, I, and salts thereof in high purity. According to the process of one aspect of this invention, a compound II, II, is diazotied and the diazonium salt obtained is coupled with a compound III, III, The formed intermedlate IV, which is also an aspect of this invention IV, is hydrolyzed in alkaline medium to form the compound I. In the above formulae, R1, R2 and R3 signify lower alkyl and R2 may also be, phenyl or phenyl which is mono- or polysubstituted by groups which are inert under conditions of diazotization or alkaline hydrolysis.
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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 April 3, 1984. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended April 3, 2001.
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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.