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:
Mar. 04, 1980
Filed:
Jun. 08, 1978
Hans H Steuernagel, Kelkheim, DE;
Ernst Hoyer, Frankfurt am Main, DE;
Hoechst Aktiengesellschaft, Frankfurt, DE;
Abstract
An improved and novel process has been found for the esterification of amino-benzoxazolone compounds containing a .beta.-hydroxyethylsulfonyl group, by means of sulfuric acid or sulfur trioxide, with simultaneous or subsequent hydrolytic cleavage of the oxazolone ring, wherein the esterification and optional hydrolytic ring cleavage are performed in a machine which is operating with a kneading action and effect, using per mol of .beta.-hydroxyethylsulfonyl compound 1 to 20 times the equivalent molar amount of concentrated sulfuric acid, oleum or sulfur trioxide. This novel process has the great advantage that great amounts of sulfuric acid are saved which would contaminate the waste-water, also in form of sodium sulfate formed after the required neutralization. Furthermore, the .beta.-sulfatoethylsulfonyl compounds formed as end-products in the esterification process are obtained in higher yields, in a higher esterification rate and in a higher purity. They may be obtained in form of a powder or plastic mass, which is conveniently transportable and storable, and can advantageously be used, if ring cleavage had taken place, without intermediate isolation of the pure sulfato compound itself, directly for the preparation of azo dyestuffs which are low in content of inert salts and possess a high tinctorial strength and purity.