Preparation of phosphorous acid
CA 2013221 C · Owner: Mcgilvery, James D. · Inventors: Twardowska, Helena; Cybulski, Slawomir M.; Mcgilvery, James D.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Phosphorous acid is formed by gaseous phase oxidation of phosphorus with water vapour to form predominantly P2O3 and dissolving the P2O3 so-formed in water. The P2O3 also can be recovered as the product by quenching the P2O3 to a stable temperature using an inert cooling medium rather than water. Oxygen also may be used in conjunction with the water vapour. Sufficiently rapid quenching of reaction products may result in the formation of red amorphous phosphorus from unreacted phosphorus.
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 March 28, 1990 and granted January 28, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 28, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 28, 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.
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.