Columnar crystals of 6-hydroxy-2-naphthoic acid and process for the production thereof
CA 2348401 A1 · Owner: Ueno, Ryuzo · Inventors: Kato, Hiroyuki; Kitayama, Masaya; Otsuka, Ryoichi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for the production of columnar crystals of 6-hydroxy-2-naphthoic acid, which comprises dissolving crude 6-hydroxy-2-naphthoic acid in an aqueous medium, adding seed crystals of 3-hydroxy-2,7-naphthoic acid or seed columnar crystals to the solution, and cooling the resulting mixture to conduct crystallization; and columnar crystals of 6-hydroxy-2-naphthoic acid produced by the process, which exhibit in the X-ray diffraction a peak 2$g (u) ranging from 16.8 to 17.8 and/or from 21.3 to 22.3 and have a high apparent specific gravity and excellent fluidity.
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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 August 18, 2000. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended August 18, 2020.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 18, 2022.
- 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
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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.