| 摘要 |
Completely esterified rhodamine dyes of the formula <IMAGE> where R, R2 and R4 are independently of one another methyl or ethyl, R1 and R3 are independently of one another hydrogen, methyl or ethyl, R5 and R6 are independently of one another hydrogen or methyl and A(-) is an anion, are prepared from compounds of the formula II <IMAGE> or from the corresponding water addition products by esterification with dialkyl sulfates in solvents by using gamma -butyrolactone, alkylene carbonates, dialkyl carbonates, methoxypropyl acetate or dialkyl phthalates as solvent and working in the presence of an excess of a base, based on dialkyl sulfate.
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