Patents by Inventor Knut Riedel

Knut Riedel 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 preparing dimethyl vinylphosphonate from dimethyl 2-acetoxyethanephosphonate
    Patent number: 5763637
    Abstract: The invention relates to a process for preparing dimethyl vinylphosphonate by thermal dissociation of dimethyl 2-acetoxyethanephosphonate in the gas phase, which comprises vaporizing dimethyl 2-acetoxyethanephosphonate and dissociating it without catalysis at a temperature of from 400.degree. to 700.degree. C. into dimethyl vinylphosphonate and acetic acid.
    Type: Grant
    Filed: January 17, 1996
    Date of Patent: June 9, 1998
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Knut Riedel, Udo Dettmeier, Guenter Roscher
  • Process for the preparation of pure crotonic acids
    Patent number: 4918225
    Abstract: The invention relates to a process for the preparation of pure cis- or trans-crotonic acid from a mixture of the two isomers by melt crystallization. To prepare trans-crotonic acid, an isomer mixture I containing at least 40% by weight of trans-crotonic acid is used as the starting material. On the other hand, if cis-crotonic acid is to be prepared, an isomer mixture II containing at least 80% by weight of cis-crotonic acid is used as the starting material. The particular isomer mixture is melted and then left to cool, trans-crotonic acid being allowed to crystrallize out of mixture I to a residual content of at least 35% by weight, and cis-crotonic acid being allowed to crystallize out of mixture II to a residual content of at least 75% by weight.
    Type: Grant
    Filed: October 2, 1985
    Date of Patent: April 17, 1990
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Siegbert Rittner, Herbert Gortz, Knut Riedel
  • Process for the extraction of carboxylic acids from dilute aqueous solutions
    Patent number: 4720577
    Abstract: The invention relates to a process for the extraction of carboxylic acids from aqueous solutions with a carboxylic acid content below 8% by weight. A mixture of an aliphatic amine with a total carbon number of at least 10 and a phenol or naphthol is used as extracting agent. The molar ratio of phenol:amine or alkylated phenol:amine or naphthol:amine is in the range from 0.1:1 to around 1.1:1.
    Type: Grant
    Filed: October 2, 1985
    Date of Patent: January 19, 1988
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Bernhard Wojtech, Walter Steppich, Dieter Freudenberger, Knut Riedel
  • Process for the manufacture of resorcinol
    Patent number: 4160113
    Abstract: The present invention is related to a process for the manufacture of resorcinols by catalytic dehydrogenation of cyclohexane diones-(1,3) in the liquid phase by means of a dehydrogenating mixture consisting of a solvent and of a catalyst containing a noble metal from Group VIII of the Periodic Table.
    Type: Grant
    Filed: November 11, 1977
    Date of Patent: July 3, 1979
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Werner H. Muller, Knut Riedel, Hans Krekeler