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:
Apr. 11, 1978
Filed:
Apr. 08, 1976
Klaus Leverenz, Leverkusen, DT;
Bayer Aktiengesellschaft, Leverkusen, DT;
Abstract
The invention relates to the preparation of azo dyestuffs which are free from sulphonic acid groups by diazotization, coupling and subsequent nucleophilic exchange of a halogen atom of the diazo component is in the o-position relative to the azo group. The process is characterized in that all the reaction steps are carried out in a neutral organic dipolar solvent, with the proviso that when using diazo components which are not diazotizable, or only incompletely diazotizable, in dilute aqueous mineral acids, the diazotization medium employed consists of aprotic solvents which do not undergo any chemical reaction with the diazonium salt of this component. The new process is distinguished by less contamination of the effluent.