Patents by Inventor Douglas W. Chapman

Douglas W. Chapman 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).

  • Patent number: 4571437
    Abstract: A process for preparing unsubstituted and alkyl substituted p-aminophenols. A charge mixture is prepared comprising an unsubstituted or alkyl substituted nitrobenzene, a highly dissociated acid, a catalyst containing platinum and a divalent sulfur compound in which sulfur is bonded to two other moieties, the sulfur compound being present in a proportion of between about 0.1 and about 100 moles per gram-atom of platinum. The mixture comprises an organic phase containing the substrate and an aqueous phase containing the acid. Hydrogen is introduced into the mixture at a pressure of 0-50 psig while the mixture is agitated at a temperature of 70.degree. C. to 100.degree. C., thereby causing the substrate to be reduced to phenylhydroxylamine or an alkyl substituted phenylhydroxylamine. The hydroxylamine is rearranged in the presence of acid to the substituted or unsubstituted p-aminophenol, which is recovered from the aqueous phase.
    Type: Grant
    Filed: July 25, 1983
    Date of Patent: February 18, 1986
    Assignee: Mallinckrodt, Inc.
    Inventors: Douglas C. Caskey, Douglas W. Chapman
  • Patent number: 4415753
    Abstract: A process for the production of unsubstituted and lower alkyl substituted p-aminophenols. A charge mixture is prepared comprising an unsubstituted or lower alkyl substituted nitrobenzene substrate, a platinum catalyst and a sulfur compound. The sulfur compound may be a divalent sulfur compound in which sulfur is bonded to two other moieties or a compound reducible to such sulfur compound under catalytic hydrogenation conditions. Hydrogen is introduced into the mixture while it is agitated at a temperature of 0.degree.-40.degree. C., thereby reducing the substrate to an unsubstituted or alkyl substituted phenylhydroxylamine. The hydroxylamine is thereafter heated to a temperature of at least 70.degree. C. and agitated at at least 70.degree. C. in the presence of a highly dissociated acid, thereby effecting rearrangement of the hydroxylamine to the corresponding p-aminophenol.
    Type: Grant
    Filed: January 29, 1982
    Date of Patent: November 15, 1983
    Assignee: Mallinckrodt, Inc.
    Inventors: Douglas C. Caskey, Douglas W. Chapman
  • Patent number: 4112238
    Abstract: Crude 2-ethylhexyl gallate is purified by crystallizing it from a system containing an aliphatic hydrocarbon solvent such as hexane and a small proportion of 2-ethylhexanol.
    Type: Grant
    Filed: February 17, 1977
    Date of Patent: September 5, 1978
    Assignee: Mallinckrodt, Inc.
    Inventors: Douglas W. Chapman, Hugh C. Bertsch