Patents by Inventor Thuyoshi Nagashima

Thuyoshi Nagashima 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).

  • Process for separation of naphthalenedisulfonic acids
    Patent number: 4324742
    Abstract: A process for separating 1,6-naphthalenedisulfonic acid, 2,6-naphthalenedisulfonic acid or 2,7-naphthalenedisulfonic acid selectively from reaction mixtures obtained by disulfonation of naphthalene under different reaction conditions is disclosed. For example, a particular disulfonation reaction of naphthalene is carried out which favors the formation of a particular isomer. This reaction mixture is diluted with water to adjust the sulfuric acid concentration to 35 to 90% by weight and the temperature is maintained at 0.degree. to 80.degree. C.; 1,6-naphthalene-disulfonic acid is selectively separated at high purity.
    Type: Grant
    Filed: August 25, 1980
    Date of Patent: April 13, 1982
    Assignee: Sugai Chemical Industry Co., Ltd.
    Inventors: Hironory Fujii, Thuyoshi Nagashima, Nobuyori Shibamoto