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:
May. 01, 1990
Filed:
Apr. 29, 1987
Gottfried Seifert, Magden, CH;
Sebastian Staubli, Magden, CH;
Josef H Wieland, Bad Sackingen, DE;
Willy Regenass, Muttenz, CH;
Martin Buerli, Magden, CH;
John G Lee, Saraland, AL (US);
Richard B Lund, Jackson, AL (US);
Ciba-Geigy Corporation, Ardsley, NY (US);
Abstract
A process for the preparation of 4-nitrotoluene-2-sulfonic acid by sulfonating 4-nitrotoluene with oleum or liquid SO.sub.3 is described. The sulfonation is carried out continuously with oleum of at least 50% concentration or liquid 100% SO.sub.3 while keeping the conversion of 4-nitro-toluene in the reaction mixture at .gtoreq.90% during the entire reaction course. The process is inherently non-polluting, and provides the product in high yield and low sulfuric acid content in a form usable for 4,4'-dinitrostilbene-2,2'-disulfonic acid production without further purification.