The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 04, 1978
Filed:
Aug. 04, 1976
Georg Grigoleit, Dorsten, Rhade, DE;
Helmut Kohler, Duisburg, DE;
Gerd Collin, Duisburg-Meiderich, DE;
Kurt Matern, Duisburg-Meiderich, DE;
Rutgerswerke Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
In a process for obtaining substantially sulfur free pure naphthalene from bituminous coal tar and thionaphthene as a by-product, a de-phenolized thionaphthene-containing naphthalene fraction from oxidative purification is extracted with concentrated sulfuric acid and acetic acid anhydride in benzene. The thionaphthene is converted into its sulfonic acid derivative and water washed from the benzene-naphthalene mixture. The benzene is distilled leaving pure naphthalene. The sulfonic acid group is cleaved from the thionaphthene with superheated steam to yield thionaphthene.