Patents by Inventor von Helmold Plessen

von Helmold Plessen 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).

  • Dioxane adducts of aromatic meta- or para-hydroxy-carboxlic acids
    Patent number: 5081263
    Abstract: The invention relates to the dioxane adducts of armoatic meta-or para-hydroxycarboxylic acids, which consist, per mole, of 1 mole of 1,4-dioxane and about 2 moles of hydroxycarboxylic acid. The invention further relates to a process for the preparation of these adducts, which comprises dissolving the hydroxycarboxylic acids in dioxane or a mixture of the latter with water or with an organic solvent and then allowing the adducts to crystallize.
    Type: Grant
    Filed: December 14, 1989
    Date of Patent: January 14, 1992
    Assignee: Hoechst Aktiengesellschaft
    Inventors: von Helmold Plessen, Siegbert Rittner