Process for the preparation of isomer-free toluene-4-sulfonic acid

US4242275A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Otto Arndt · Hofheim, DE
• Bernhard Mees · Charlotte, US

Key dates

• Filing date: Dec 5, 1979
• Grant date: Dec 30, 1980
• Expiry date: Dec 5, 1999

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C303/06
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Pure toluene-4-sulfonic acid is obtained without forming any by-products by sulfonating toluene with sulfuric acid at an elevated temperature, separating a first batch of toluene-4-sulfonic acid hydrate, washing it free of isomers with sulfuric acid, combining the mother liquor and the washing effluent, heating them, allowing a second batch of hydrate to crystallize and, optionally, working up the final mother liquor by hydrolizing the toluene sulfonic acids therein and recycling the toluene so formed and the sulfuric acid after concentrating it to its initial strength.