Patents by Inventor Wolfgang Rybczynski

Wolfgang Rybczynski 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).

  • Process for the preparation of &agr;,&agr;- dimethylphenylacetic acid from &agr;,&agr;-dimethylbenzyl cyanide under normal pressure
    Patent number: 6281383
    Abstract: A process for obtaining &agr;,&agr;-dimethylphenylacetic acid wherein &agr;,&agr;dimethylbenzyl cyanide is reacted in the presence of sodium hydroxide, water and a C4- and/or C5-alcohol at temperatures above about 100° C. and the &agr;,&agr;-dimethylphenylacetic acid is obtained by acidification.
    Type: Grant
    Filed: September 24, 1999
    Date of Patent: August 28, 2001
    Assignee: Aventis Pharma Deutschland GmbH
    Inventors: Gerhard Korb, Hans-Wolfram Flemming, Rudolf Lehnert, Wolfgang Rybczynski
  • Method of preparing 1-amino-2, 6-dimethylpiperidine
    Patent number: 5510489
    Abstract: The present invention relates to improved processes for the preparation of 1-amino-2,6-dimethylpiperidine whereby the yield is more than 90%. The processes involve the hydrogenation of 1-nitroso-2,6-dimethylpiperidine in the presence of a palladium catalyst which is partly poisoned with iron ions, in an aqueous solvent, and are characterized by the inclusion of at least one surfactant. The surfactant preferably is anionic or nonionic.
    Type: Grant
    Filed: May 17, 1994
    Date of Patent: April 23, 1996
    Assignee: Cassella Aktiengesellschaft
    Inventors: Wolfgang Rybczynski, Wolfgang Bauer, Eckard Kujath, Manfred Schrod