| 摘要 |
Cationic dyestuffs of the general formula <IMAGE> (I) wherein R1 represents hydrogen, C1-C4-alkyl, C1- to C4- alkoxy, nitro or halogen, R2 represents hydrogen, C1- to C4-alkyl, C1- to C4-alkoxy, halogen or phenylazo, R3 represents C1- to C3-alkyl and A(-) represents an anion, are prepared by reacting azo bases of the general formula <IMAGE> II wherein R1, R2 and R3 have the abovementioned meaning, with dialkyl sulphates of the general formula (R3-O-)2SO2 (III) wherein R3 has the abovementioned meaning, in the absence of organic solvents and in the presence of water, the weight ratio of azo base to water being 100:15-100 and the molar ratio of azo base to dialkyl sulphate being 1:1.5-2.5, and, if desired, by replacing the alkyl-sulphate anion with another anion.
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