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Expired Canadian patentCanada

Process for the production of substantially pure gamma-butyrolactone

CA 1305715 C · Owner: Wood, Michael A. · Inventors: Wood, Michael A.

CIPO record

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Abstract From the Canadian patent

A process is described for the production of substantially pure gamma-butyrolactone from a feed mixture containing a major amount of gamma-butyrolactone and a minor amount of diethyl succinate which comprises fractionally distilling the mixture in a fractionation zone in the presence of diethyl ethoxysuccinate and recovering from the fractionation zone an overhead vaporous product comprising gamma-butyrolactone which is substantially free from diethyl succinate and a liquid bottom product comprising diethyl ethoxysuccinate and diethyl succinate in admixture one with another. This procedure can be used to separate a gammabutyrolactone rich fraction obtained by distillation in one or more …

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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 July 28, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended July 28, 2009.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJuly 26, 1988
GrantedJuly 28, 1992
Term endedJuly 28, 2009
Patent numberCA 1305715 C
Classification (IPC)C07D307/32 +1 more

Timeline

Timeline From CIPO dates

1989199219951998200120042007Application filedJuly 26, 1988Patent grantedJuly 28, 1992Term endedJuly 28, 2009

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.