Patents by Inventor Dwight E. Raff, II

Dwight E. Raff, II 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: 4870209
    Abstract: A process for the purification of crude 4-aminophenol which was prepared by the catalytic hydrogenation of nitrobenzene in aqueous sulfuric acid is described involving: adjusting the pH of an aqueous solution of crude 4-aminophenol to pH 4.0-5.0 at a temperature between 75.degree. C. and 85.degree. C.; mixing the aforesaid solution with toluene as the solvent, in order to extract various impurities and the dissolved nitrobenzene starting material; adjusting the pH of the resultant solution as required to maintain it at pH 4.0-5.0; allowing the resultant mixture to settle thereby forming a top organic layer and a bottom aqueous raffinate layer which raffinate contains 4-aminophenol and the by-product material, ortho-aminophenol; separating the two layers and repeatedly extracting the raffinate layer which toluene at pH 4.0-5.0 at a temperature of 75.degree.-85.degree. C.
    Type: Grant
    Filed: April 29, 1987
    Date of Patent: September 26, 1989
    Assignee: Noramco, Inc.
    Inventors: James T. F. Kao, Dwight E. Raff, II