Patents by Inventor Siegbert Rittner

Siegbert Rittner 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 purification of 2-hydroxynaphthalene-6-carboxylic acid
    Patent number: 4916257
    Abstract: The invention relates to a process for purification of 2-hydroxynaphthalene-6-carboxylic acid by recrystallization. In this process, the crude acid is recrystallized from water-miscible linear or cyclic aliphatic ethers, aliphatic polyethers or aliphatic hydroxy ethers or from at least 10% strength by weight aqueous solutions of these ethers. Recrystallization from a 35-90% strength by weight aqueous solutions of 1,4-dioxane is particularly preferred.
    Type: Grant
    Filed: January 12, 1989
    Date of Patent: April 10, 1990
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Helmold von Plessen, Siegbert Rittner, Heinrich Volk, Werner Wykypiel, Rudolf Neeb
  • Process for removing halogenated hydroxyaromatics from aqueous solutions
    Patent number: 4864065
    Abstract: The invention relates to a process for extracting halogenated hydroxyaromatics from aqueous solutions. In this process, the extractant used is an amine salt comprising an aliphatic amine having a total carbon number of 10 to 75 and a strong acid. The amine salt may be employed in undiluted form or diluted with an organic solvent.
    Type: Grant
    Filed: June 1, 1988
    Date of Patent: September 5, 1989
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Bernhard Wojtech, Siegbert Rittner, Heinz Reiss, Reinhard Zunder
  • Process for extracting nitrohydroxyaromatics from aqueous solutions
    Patent number: 4814518
    Abstract: The invention relates to a process for extracting nitrohydroxyaromatics from aqueous solutions. In this process, the extracting agent used is an amine salt which comprises an aliphatic amine having a total carbon number of 10 to 75 and a strong acid. The amine salt can be employed undiluted or diluted with an organic solvent.
    Type: Grant
    Filed: August 12, 1987
    Date of Patent: March 21, 1989
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Helmut Gossel, Herbert Kuckertz, Siegbert Rittner, Josef Rosenfelder, Bernhard Wojtech
  • Process for separating dimethyl isophthalate and dimethyl orthophthalate from their mixture with dimethyl terephthalate
    Patent number: 4683034
    Abstract: The invention relates to a process for separating dimethyl isophthalate (DMI) and dimethyl orthophthalate (DMO) and other by-products from their mixture with dimethyl terephthalate (DMT), formed in the oxidation of p-xylene followed by esterification with methanol, by crystallization from the melt.Initially, the esterification product is here distilled once or several times. The DMT-rich fraction obtained is then subjected wholly or partially to one or several crystallizations from the melt, and the DMI-DMO fraction thus obtained is at least partially removed from the system. As an alternative, the DMT-rich fraction is first recrystallized from methanol, the methanol is then evaporated from the mother liquor and the remaining residue is subjected to one or several crystallizations from the melt. The DMI-DMO fraction thus obtained is again at least partially removed from the system.
    Type: Grant
    Filed: August 16, 1985
    Date of Patent: July 28, 1987
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Rolf Bader, Hartmut Last, Manfred Mayer, Siegbert Rittner, Edgar Wetzel
  • Process for improving the wetting characteristics of the surface of shaped plastics articles for applications in chemical engineering
    Patent number: 4617197
    Abstract: It is possible, by means of a flame-spraying or plasma-spraying technique adjusted to suit the particular properties of a plastic, not only to provide nonreinforced plastics with a uniform coating, but also to achieve an excellent hydrophilic surface wettability at the same time.
    Type: Grant
    Filed: May 24, 1985
    Date of Patent: October 14, 1986
    Assignee: Hoechst Aktiengesellschaft
    Inventors: Siegbert Rittner, Eugen Morach, Hubert Schindler, Peter John