Patents by Inventor Rex D. Roberts

Rex D. Roberts 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 2-aryl-2H-benzotriazoles
    Patent number: 4224451
    Abstract: A two stage reductive ring closure of o-nitrophenylazophenols produces 2-aryl-2H-benzotriazoles by (a) reacting an organic solvent solution of azophenol with an excess of an aqueous solution of a sulfhydrate or sulfide to form an N-oxide and (b) reducing the N-oxide with an alkali metal hydroxide plus zinc or tin.
    Type: Grant
    Filed: December 20, 1978
    Date of Patent: September 23, 1980
    Assignee: American Cyanamid Company
    Inventors: Rex D. Roberts, William B. Hardy