Study On The New Synthetic Technology Of 2-(4-aminophenylsulfonyl)ethyl Hydrogen Sulfate

2-(4-aminophenylsulfonyl)ethyl hydrogen sulfate is important intermediate of active dyes of KN-type,KM-type and M-type, which have been produced for 50 years. But the quality of product has been too poor to export and it has effected on the quality of active dyes. Recently the producing technology has been improved, but the cost of production and environmental pollution have not improved yet, and the quality of production is not better than the overseas one, so the share of production is small for China.To the actuality , in this paper, the new synthetic technology of 2-(4-aminophenylsulfonyl)ethyl hydrogen sulfate was researched. As compared with old technology, the new one have the characters of reducing the pollution and the cost.Using 1-chloro-4-nitrobenzene as starting material, 4-aminobenzenethiol was obtained by substitution and deoxidization, and under the temperature of 70℃, the new-made sodium sulfide solution was added dropwise to accelerate reaction rate. At the temperature of 100℃, the reaction has been carried by heating and the end point of reaction was indicated by TLC (thin layer chromatography),the optimal synthetic conditions were obtained by the experiments: the molar ratio of 1-chloro-4-nitrobenzene to water is 1:11; the optimal reaction temperature of substitution is 70℃and the optimal reaction time is 240 min; the optimal reaction temperature of deoxidization is 100℃and the optimal reaction time is 120 min. The best yield is 86.31 % at the optimal synthetic conditions.The condensation reaction was done by using inexpensive and commercial compound of 2-chloroethanol, the pH of solution was adjusted to 7～8 by NaOH(aq.). Under the condition of the molar ratio of 4-aminobenzenethiol to 2-chloroethanol is 1:1.1, the optimal synthetic conditions were obtained by the experiments: the optimal reaction temperature is 70℃and the optimal reaction time is 180 min. The best yield is 87.90 % at the optimal synthetic conditions.The acylation of 2-(4-aminophenylthio)ethanol was done by using acetic anhydride as acylating reagent in order to protect amino group, the protecting effect of amino group was good, which can be noticed in the measure of amino value of the terminal product (amino value: 98.24 %), and in comparison with acetic acid chloride, no acidic fog was produced, lower the pollution and the price of acetic anhydride is 1/3 one of acetic acid chloride. The optimal synthetic conditions were obtained by the experiments: the optimal molar ratio of 2-(4-aminophenylthio)ethanol to acetic anhydride is 1:2.2; the optimal reaction time is 120 min. The best yield is 96.20 % at the optimal synthetic conditions.In this synthetic technology, 2- ( 4-acetaminophenylthio)ethyl acetate was oxidated by hydrogen peroxide using water as reaction solvent. In the experiment, considering the decomposition and the volatility of H2O2, the better molar ratio of H2O2 to substrate is 2.1～2.2 and the pH of solution was adjusted to 5.5～7 by HCl(aq.) and the optimal reaction time is 300 min at 60℃. The best yield is 95.89 % at the optimal synthetic conditions. 1 mL ethanol was added in order to elimination of bubbling in the course of reaction when the rapid decomposation of H2O2 will cause occasionally foaming.Liquid-phase synthesis was used in the esterification craft and made the reactants carrie on the esterification under the good flow condition. This method had many advantages, for example: the transform rate is high, uses the equipment to be simple, the operation is easy, the product purity is high, the difference of the amino value to the value of esterification is small and do not have the vinegar sour odor. The optimal hydrolysis synthetic conditions were obtained by the experiments: the molar ratio of oxide production to water is 1:13; the optimal reaction temperature of substitution is 95～100℃and the optimal reaction time is 150 min. The optimal esterification synthetic conditions were 140℃and 300 min. By the experiments, the molar ratio of oxide production to sulphuric acid is 1:4 and the volume ratio of sulphuric acid to water is 1:2 that can make the reaction easy to reach the optimal reaction temperature under the suitable water dosage. The best yield is 87.54 % at the optimal synthetic conditions.In this synthetic technology, 1-chloro-4-nitrobenzene was used as starting material and the target product (2-(4-aminophenylsulfonyl)ethyl hydrogen sulfate)was obtained by substitution, deoxidization, condensation, acetylization, oxidation, hydrolysis and liquid-phase esterification. While determined that each step best synthesis condition, the important synthetic intermediate and the target product were characterized by IR, 1H-NMR and element analysis. The high grade product has the ivory white appearance and its amino value is 98.24 %, the value of esterification is 96.14 %. The total yield is 61.26 % according to the usage of 1-chloro-4-nitrobenzene.