Patents by Inventor Nobuhito Koga

Nobuhito Koga 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: 4289699
    Abstract: N-(hydroxyphenyl) maleimides of the general formula ##STR1## where R' stands for H, CH.sub.3, C.sub.2 H.sub.5, F, Cl, Br or I and n is an integer of 1-5 are produced by treating the corresponding maleamic acid or by treating the ester of said N-(hydroxyphenyl) maleimide at a temperature of 0.degree.-150.degree. C. in the presence of at least one dehydrating agent selected for the group consisting of oxides and oxyacids of sulfur or phosphorus and alkali metal and alkaline earth metal salts of the said oxyacids. The corresponding maleamic acid can be obtained by reacting an aminophenol having one or more hydroxyl groups on its phenyl nucleus with maleic anhydride. The esters of the N-(hydroxyphenyl maleimide) can be obtained by reacting said aminophenol and said maleic anhydride in the presence of a conventional acid anhydride dehydrating agent and a conventional imide-forming cyclization catalyst.
    Type: Grant
    Filed: October 26, 1979
    Date of Patent: September 15, 1981
    Assignee: Mitsui Toatsu Chemicals, Incorporated
    Inventors: Masayuki Oba, Motoo Kawamata, Hikotada Tsuboi, Nobuhito Koga
  • Patent number: 4231934
    Abstract: N-(hydroxyphenyl) maleimides of the general formula ##STR1## where R' stands for H, CH.sub.3, C.sub.2 H.sub.5, F, Cl, Br or I and n is an integer of 1-5 are produced by treating the corresponding maleamic acid or by treating the ester of said N-(hydroxyphenyl) maleimide at a temperature of 0-150.degree. C. in the presence of at least one dehydrating agent selected from the group consisting of oxides and oxyacids of sulfur or phosphorus and alkali metal and alkaline earth metal salts of the said oxyacids. The corresponding maleamic acid can be obtained by reacting an aminophenol having one or more hydroxyl groups on its phenyl nucleus with maleic anhydride. The esters of the N-(hydroxyphenyl maleimide) can be obtained by reacting said aminophenol and said maleic anhydride in the presence of a conventional acid anhydride dehydrating agent and a conventional imide-forming cyclization catalyst.
    Type: Grant
    Filed: November 2, 1978
    Date of Patent: November 4, 1980
    Assignee: Mitsui Toatsu Chemicals, Incorporated
    Inventors: Masayuki Oba, Motoo Kawamata, Hikotada Tsuboi, Nobuhito Koga