Method of preparation of ascorbic acid

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 11, 1990 and granted May 8, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 11, 2010.
• A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 11, 2012.
• We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.