Patents by Inventor Hans-Heinrich Lenz

Hans-Heinrich Lenz 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 3,7-dialkylxanthines
    Patent number: 5210192
    Abstract: The invention is directed to a process for preparing 3,7-dialkylxanthines of the formula I ##STR1## (R.sup.1 and R.sup.2 denote C.sub.1 -C.sub.4 -alkyl) by the reaction of 4-amino-imidazolecarboxamide-(5) of the formula II ##STR2## with an alkali cyanate in aqueous solution at a pH of from 3 to 5 followed by cyclization of the resulting urea derivative at a pH of from 8 to 14.
    Type: Grant
    Filed: March 2, 1992
    Date of Patent: May 11, 1993
    Assignee: BASF Aktiengesellschaft
    Inventors: Marius Bugglin, Herbert Gropp, Lothar Janitschke, Ulrich Karl, Hans-Heinrich Lenz
  • Gas-phase alkylation of phenols, and a catalyst for this purpose
    Patent number: 4753913
    Abstract: The proposed catalyst for the gas-phase alkylation of phenols is based on magnesium oxide, contains up to 0.4% by weight of alkali metal oxide and is mechanically stabilized with from 1 to 8% by weight, based on the total weight of the catalyst, of graphite, molded and then heated.
    Type: Grant
    Filed: July 8, 1986
    Date of Patent: June 28, 1988
    Assignee: BASF Aktiengesellschaft
    Inventors: Hans-Heinrich Lenz, Eckhard Roske, Karl Baer
  • Preparation of .alpha.-methyl-substituted ketones
    Patent number: 4618725
    Abstract: .alpha.-Methyl-substituted ketones are prepared by reacting the corresponding unsubstituted ketones, which must possess two or more geminal hydrogen atoms in the .alpha.-position, with methanol in the gas phase at from 350.degree. to 500.degree. C. and under from 1 to 20 bar in the presence of a metal oxide.
    Type: Grant
    Filed: June 13, 1985
    Date of Patent: October 21, 1986
    Assignee: BASF Aktiengesellschaft
    Inventor: Hans-Heinrich Lenz