Patents by Inventor Yuo-Guo Pan

Yuo-Guo Pan 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).

  • Hair dye compositions containing anthraquinone dyes having a quaternary ammonium side chain and neutral direct dyes
    Patent number: 5891200
    Abstract: Anthraquinone compounds of formula I ##STR1## wherein R.sub.1 and R.sub.2 are methyl and R.sub.3 is propyl, or R.sub.1 and R.sub.2 are ethyl and R.sub.3 is methyl and A is a cosmetically acceptable anion, are combined neutral, with semipermanent direct dyes in hair dyeing compositions.
    Type: Grant
    Filed: February 26, 1996
    Date of Patent: April 6, 1999
    Inventors: Mu-Ill Lim, Linas Stasaitis, Yuo-Guo Pan
  • Methods for dyeing hair with anthraquinone hair dyes having a quaternary ammonium side chain
    Patent number: 5520707
    Abstract: Anthraquinone compounds of formula I ##STR1## wherein R.sub.1 and R.sub.2 are methyl and R.sub.3 is propyl, or R.sub.1 and R.sub.2 are ethyl and R.sub.3 is methyl and A.sup.- is a cosmetically acceptable anion, are useful for the dyeing of hair. Compounds of formula I may advantageously be employed with direct dyes. Compositions and a method of use employing same are disclosed.
    Type: Grant
    Filed: August 7, 1995
    Date of Patent: May 28, 1996
    Assignee: Clairol, Inc.
    Inventors: Mu-Ill Lim, Linas Stasaitis, Yuo-Guo Pan
  • Synthesis of 2-methyl-1-naphthol
    Patent number: 5420362
    Abstract: 4-Halo-1-naphthol is reacted with a secondary amine and formaldehyde to produce a reaction mixture containing a Mannich base which is hydrogenated to produce 2-methyl-1-naphthol. Advantageously, the procedure can be carried out in one pot.
    Type: Grant
    Filed: October 8, 1993
    Date of Patent: May 30, 1995
    Assignee: Clairol, Inc.
    Inventors: Mu-Ill Lim, Linas Stasaitis, Yuo-Guo Pan, Alexander Chan