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US 5,280,128 AGranted
Process for the preparation of benzothioxanthene dyestuffs
AssigneeCassella Aktiengesellschaft
InventorsWolfgang Bauer, Eberhard Grimm, Uwe Nickel, Manfred Schrod, Herbert Wille
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Abstract
The present invention relates to a process for the preparation of benzothioxanthene dyestuffs and cyclisation of 3-(2'-aminophenylthio)-benzanathrones wherein the diazotisation and cyclisation are carried out simultaneously in polar, aprotic solvent in the presence of water.
Claims10
Process for the preparation of benzothioxanthene dyestuffs of the general formula I ##STR8## wherein R.sup.1 and R.sup.2 independently of one another denote hydrogen, (C.sub.1 -C.sub.2)-alkyl, (C.sub.1 -C.sub.2)-alkoxy or chlorine and
- R.sup.3 and R.sup.4 independently of one another denote hydrogen or bromine, by diazotisation and cyclisation of 3-(2'-aminophenyl-thio)-benzanthrones of the general formula II ##STR9## wherein R.sup.1 to R.sup.4 are defined as mentioned above, comprising the diazotisation and cyclisation are carried out simultaneously in polar, aprotic solvents in the present of water in amounts of 2% to 10% weight, based on the solvent.
Dependencies are inferred from the claim text.