Patents by Inventor John D. Hildreth

John D. Hildreth 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).

  • Catalytic reduction of 2-nitronaphthalene-4,8-disulfonic acid ammonium salt
    Patent number: 4299779
    Abstract: 2-Naphthylamine-4,8-disulphonic acid is produced by catalytically hydrogenating the ammonium salt of 2-nitronaphthalene-4,8-disulphonic acid using Pt/C or Pd/C as the catalyst.
    Type: Grant
    Filed: December 15, 1980
    Date of Patent: November 10, 1981
    Assignee: Clayton Aniline Co., Ltd.
    Inventor: John D. Hildreth
  • Composition of 4-amino-4'-nitrostilbene-2,2'-disulphonic acid diazo compounds and coloring process
    Patent number: 4266939
    Abstract: The invention provides dyestuffs of the general formula ##STR1## in which R is hydrogen or an alkyl group having 1 to 6 carbon atoms and R' is an alkyl group having 1 to 6 carbon atoms.
    Type: Grant
    Filed: June 4, 1979
    Date of Patent: May 12, 1981
    Assignee: Ciba-Geigy Corporation
    Inventors: John D. Hildreth, Anton F. Tschopp, David G. Evans
  • Production of 2,4- and 2,6-diaminotoluenes
    Patent number: 4256671
    Abstract: A process for the manufacture of 2,4- and 2,6-diaminotoluenes comprises catalytically hydrogenating the corresponding molten nitro compound in the presence of water, adding hydrochloric acid to form the monohydrochlorides, crystallizing 2,6-diaminotoluene monohydrochloride, filtering it off and, if desired, liberating the free bases by addition of an alkali.
    Type: Grant
    Filed: May 11, 1979
    Date of Patent: March 17, 1981
    Assignee: Clayton Aniline Company, Ltd.
    Inventors: John D. Hildreth, David G. Haslam, David E. Allen