Patents by Inventor Doo C. Na

Doo C. Na 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: 5495057
    Abstract: There is disclosed a method for the preparation of difluoromethane wherein methylene chloride is reacted with. hydrogen fluoride in liquid phase, at a temperature of about 70.degree. to 90.degree. C. under a pressure of about 11 to 12 kg/cm.sup.2.g in the presence of antimony pentachloride. It is important that the concentration of quinquevalent antimony is maintained at a level of 85% or more with the feed mole ratio of hydrogen fluoride to methylene chloride ranging from about 2.0 to 2.3.Applicable to industrial scale, the method is operated in a batch system or in a continuous system. In addition, it exhibits superior conversion rate of the materials and production yield.
    Type: Grant
    Filed: March 2, 1995
    Date of Patent: February 27, 1996
    Assignee: Ulsan Chemical Co., Ltd.
    Inventors: Kyung H. Nam, Doo C. Na, Dae S. Kim