Patents Examined by Covington Raymond
  • Process for the preparation of 1-hydroxy-4-amino-5(8)-nitroanthraquinone
    Patent number: 4424160
    Abstract: 1-Hydroxy-4-amino-5- or -8-nitroanthraquinone is obtained in high yields and in high purity when 1,8-dinitroanthraquinone or 1,5-dinitroanthraquinone respectively is reacted below 80.degree. C. in oleum in the presence of boric acid with reducing agents. The products of the process are valuable polyester dyestuffs as well as dyestuff intermediate products.
    Type: Grant
    Filed: June 16, 1982
    Date of Patent: January 3, 1984
    Assignee: Bayer Aktiengesellschaft
    Inventors: Volker Hederich, Gu/ nter Gehrke