Patents by Inventor Nadezhda S. Trofimova

Nadezhda S. Trofimova 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 the preparation of photochromic compounds of the annelated spiro?indoline?2,3'! benzoxazine!type
    Patent number: 5831090
    Abstract: The present disclosure relates to a process for the preparation of photochromic compounds of the annelated spiro?indoline?2,3'!benzoxazine! type comprising the reaction of a Fisher base (I) having a 2-alkylidene indoline structure with a condensed ortho-aminophenol compound (II) in the presence of an oxidizing agent. The Fisher base, condensed ortho-aminophenol and the oxidizing agent may be mixed together simultaneously in order to carry out the reaction. Alternatively, the oxidizing agent may be reacted with the Fisher base in a first step and condensed ortho-aminophenol may then be added to the reaction mixture thus obtained.
    Type: Grant
    Filed: April 4, 1997
    Date of Patent: November 3, 1998
    Assignee: Essilor International - Compagnie Generale D'Optique
    Inventors: Victor A. Paltchkov, Nikolai E. Chelepin, Vladimir I. Minkin, Nadezhda S. Trofimova, Oleg A. Zoubkov