Patents by Inventor Achim Riemann

Achim Riemann 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 for making aromatic phosphorus compounds
    Patent number: 4698448
    Abstract: Compounds of the formula ##STR1## wherein R is lower alkyl or aryl, Y is oxygen or sulfur, m is 0 or 1, Ar is arylene, and X is halogen, methyl, or aryloxy, or polymers containing repeating units of this kind are prepared from a compound R--P(Y).sub.r Cl.sub.2, where r is 0 or 1 but is never greater than m, by reaction with one or two molar parts of a compound H--ArX in the presence of a Friedel-Crafts catalyst.
    Type: Grant
    Filed: July 2, 1985
    Date of Patent: October 6, 1987
    Assignee: Rohm GmbH
    Inventors: Werner Ude, Siegmund Besecke, Achim Riemann, Guenther Schroeder
  • Method for making 9,9-bis-(4-hydroxyphenyl)-fluorene
    Patent number: 4675458
    Abstract: A method for making 9,9-bis-(4-hydroxyphenyl)-fluorene by reacting fluorenone with phenol at a temperature from 20.degree. to 100.degree. C. in the presence of sulfuric acid of a concentration higher than 70 percent and of a mercaptan, and particularly beta-mercaptopropionic acid, as acidic condensing agents.
    Type: Grant
    Filed: October 3, 1985
    Date of Patent: June 23, 1987
    Assignee: Ronm GmbH
    Inventors: Achim Riemann, Werner Ude
  • Method for making 4,4'-dihydroxydiphenyl ether
    Patent number: 4638099
    Abstract: A method for making 4,4'-dihydroxydiphenyl ether from diphenyl ether by oxidatively iodinating diphenyl ether to 4,4'-diiododiphenyl ether and/or 4-hydroxy-4'-iododiphenyl ether, hydrolyzing this product with a base, recovering iodine from the solution containing iodide, and recycling the iodine to the iodination step.
    Type: Grant
    Filed: January 23, 1986
    Date of Patent: January 20, 1987
    Assignee: Rohm GmbH
    Inventors: Achim Riemann, Werner Ude