| 摘要 |
An aqueous alkylation process at high pH and temperatures of 0-30 DEG C is described for the preparation of cationic hydrazone dyestuffs of the formula <IMAGE> in which R1 and R2 each denote a methyl or ethyl radical, n denotes 1 or 2, X<(-)> denotes the charge equivalent of an anion and B denotes a divalent radical which completes the ring a to give an unsubstituted or chlorine- or methyl-substituted pyridinium or quinolinium ring and where the ring b is unsubstituted or substituted by low molecular weight alkyl or alkoxy or by halogen. The dyestuffs are prepared by treating a compound of the formula <IMAGE> in which R1, n, X<(-)>, B, a and b have the same meaning as above and m is 1 or 2, in aqueous medium at a pH of 12 or higher with dimethyl or diethyl sulphate, where if m is equal to 1, at least 2 equivalents of dimethyl sulphate or diethyl sulphate are used. The process permits the preparation of the dyestuffs in a one-pot process and without the use of organic solvents.
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