Patents by Inventor Hong A. Nguyen

Hong A. Nguyen 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: 5387725
    Abstract: Compounds having acidic protons and a molecular structure which can delocalize the electron density of the conjugate base (target compounds) are chlorinated by contacting such compounds with a perchloroalkane and aqueous base in the presence of a phase transfer catalyst which is an tetraalkylammonium hydroxide. Chlorinated products, preferably gem-dichloro compounds, are produced. The gem-dichloro compounds are useful for alkylation of aromatic compounds. For instance fluorene is chlorinated to form 9,9-dichlorofluorene which is reacted with such compounds as phenol or aniline to form such compounds as 9,9-bis(hydroxyphenyl)fluorene, 9,9-bis(aminophenyl)fluorene, or 9-aminophenyl-9-chlorofluorene.
    Type: Grant
    Filed: July 12, 1993
    Date of Patent: February 7, 1995
    Assignee: The Dow Chemical Company
    Inventors: Marlin E. Walters, W. Frank Richey, Katherine S. Clement, Steven L. Brewster, Emmett L. Tasset, Paul M. Puckett, V. Rao Durvasula, Hong A. Nguyen
  • Patent number: 5202102
    Abstract: A process is disclosed which comprises: contacting a catalyst such as alumina silica, aluminosilicates, titanium oxide, magnesium oxide, and the metals of Groups III and IIB of the Periodic Table under reducing conditions with a gaseous mixture comprising elemental chlorine gas and a diluent under conditions effective to improve the ability of the catalyst to dehydrohalogenate halogenated hydrocarbons: contacting the catalyst with a halogenated hydrocarbon feedstock, the halogenated hydrocarbon feedstock with or without a carrier gas, in the gas phase under dehydrohalogenation conditions; and recovering a dehydrohalogenated product.
    Type: Grant
    Filed: May 22, 1991
    Date of Patent: April 13, 1993
    Assignee: The Dow Chemical Company
    Inventor: Hong A. Nguyen