Patents by Inventor Stefan Essl

Stefan Essl has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method of production of 9-cis-retinoic acid
    Patent number: 8536373
    Abstract: Improved method of production of 9-(Z)-retinoic acid, in which a) a ?-formyl-crotonic acid C1-C10 alkyl or phenyl ester is reacted with an isolated 9-(Z)—C15-triarylphosphonium salt by the Wittig reaction in the presence of a base to the corresponding 9-(Z)-retinoic acid ester; which b) is then saponified with a base to the corresponding 9-(Z)-retinoic acid carboxylate and then, following protonation with an acid, the desired 9-(Z)-retinoic acid is obtained, and improved method for the enrichment and isolation of the 9-(Z)—C15-triarylphosphonium salt.
    Type: Grant
    Filed: September 27, 2007
    Date of Patent: September 17, 2013
    Assignee: DSM IP Assets B.V.
    Inventors: Michael Stanek, Stefan Essl, Monika Knopp, Erwin Kübel
  • METHOD OF PRODUCTION OF 9-CIS-RETINOIC ACID
    Publication number: 20100217037
    Abstract: Improved method of production of 9-(Z)-retinoic acid, in which a) a ?-formyl-crotonic acid C1-C10 alkyl or phenyl ester is reacted with an isolated 9-(Z)—C15-triarylphosphonium salt by the Wittig reaction in the presence of a base to the corresponding 9-(Z)-retinoic acid ester; which b) is then saponified with a base to the corresponding 9-(Z)-retinoic acid carboxylate and then, following protonation with an acid, the desired 9-(Z)-retinoic acid is obtained, and improved method for the enrichment and isolation of the 9-(Z)—C15-triarylphosphonium salt.
    Type: Application
    Filed: September 27, 2007
    Publication date: August 26, 2010
    Inventors: Michael Stanek, Stefan Essl, Monika Knopp