| 摘要 |
An improved and novel process had been found for the esterification of aminophenol, amino-benzanilide and pyrazolone compounds containing a beta -hydroxyethylsulfonyl group, by means of sulfuric acid or sulfur trioxide which improvement is characterized by that the esterification is performed in a machine which is operating with a kneading action and effect, using per mol beta -hydroxyethylsulfonyl compound 1 to 2.5 times the equivalent molar amount of concentrated sulfuric acid, oleum or sulfur trioxide. This novel process has the great advantage that great amounts of sulfuric acid are saved which could charge the waste water, also in form of sodium sulfate formed after the required neutralization. Furthermore, the beta -sulfatoethylsulfonyl compounds formed as end-products in the esterification process are prepared by this novel process in higher yields, in a higher degree of esterification rate and in a higher purity. They are obtained in form of a powder or plastic mass from the kneading machine, which is well transportable and storable, and can advantageously used in the form of this consistency, without intermediate isolation of the pure beta -sulfato compound itself, directly for the preparation of azo dyestuffs which are poor of inert salts, possess a high tinctorial strength and purity. |
