Synthesis Of 1-Arylethanesulfonic Acids

1-Arylethanesulfonic acids are strongly acidic resolving agents. In comparison with camphor sulfonic acid, 1-arylethanesulfonic acids with simple structure are ea-sily synthesized. 1-Arylethanesulfonic acids will be a better substitute for camphor sulfonic acid as resolving agents. The synthetic methods of 1-arylethanesulfonic aci-ds are discussed in this paper.In this paper, four different synthesizing methods of 1-Arylethanesulfonic acids are tried, such as oxidation of thiol, sodium sulphite substitution, ammonium hyr-ogensulfite substitution and sodium bisulfite substitution. Four 1-arylethanesulfonic acids are 1-phenylethanesulfonic acid, 1-(4-bromophenyl)-ethanesulfonic acid, 1-(4-c-hlorophenyl)-ethanesulfonic acid and 1-(4-nitrophenyl)-ethanesulfonic acid. The 1-ar-ylethanesulfonic acids can be got by four synthesizing methods. By using IR, MS, UV and NMR tests, the structures of the acids are all correct.The total yields of 1-phenylethanesulfonic acid and 1-(4-bromophenyl)-ethanesulfonic acid via oxidation method are 23 % and 24 % respectively. The total yields of 1-(4-chlorophenyl)-et-hanesulfonic acid and 1-(4-nitrophenyl)-ethanesulfonic acid via sodium sulphite sub-stitution are 7 % and 26 % respectively.The purification of 1-arylethanesulfonic acids is both the difficulty and the in-novation in this paper. 1-Arylethanesulfonic acids via oxidation of thiol are purified according to the solubility difference between sodium 1-arylethanesulfonates and sodium sulfate in isopropyl alcohol or methanol. After the completion of oxidation reaction, sodium sulphite was used to deactivate the excess amount of hydrogen p-eroxide, and sodium sulfate was obtained. Sodium 1-arylethanesulfonates dissolve in isopropyl alcohol and methanol with better solubilities, while sodium sulfate gives poor solubility in isopropyl alcohol and methanol. Based on solubility differentces,crude sodium 1-arylethanesulfonates containing sodium sulfate can be purified in is-opropyl alcohol and methanol, and then pure sodium 1-arylethanesulfonates are obt-ained by evaporation of the solvents. The percentage of sodium 1-arylethanesulfon-ate in crude sodium 1-arylethanesulfonates containing sodium sulfate is about 60 %~70 %. By purification process, the percentage of sodium 1-arylethanesulfonate is more than 92 % with purification yields more than 97 %. The purification procedu-re is easy to operate.The purification process not only avoids using dimethylsulfide to deactivate hyrogen peroxide in the literature but also absents from higher boili-ng point dimethylsulfoxide as a residue which is oxidation product of dimethylsulf-ide. The purification is one of the best purification methods for sodium 1-aryletha-nesulfonates.1-Arylethanesulfonic acids via sodium sulphite substitution or sodium bisulfite substitution are purified form sodium sulphite or sodium bisulfite according to the solubility difference. Sodium 1-arylethanesulfonates dissolve in isopropyl alcohol and methanol with better solubilities, while sodium sulphite or sodium bisulfite giv-es poor solubility in isopropyl alcohol and methanol. The percentage of sodium 1-arylethanesulfonate in crude sodium 1-arylethanesulfonates containing inorganic sa-lt is about 20 %~60 %. By purification process, the percentage of sodium 1-arylethane-sulfonate is more than 90 % with purification yields more than 97 %.1-Arylethanesulfonic acids via ammonium hyrogensulfite substitution are purifi-ed form ammonium hyrogensulfite according to the solubility difference. Ammoniu-m 1-arylethanesulfonates dissolve in isopropyl alcohol with better solubilities, while ammonium hyrogensulfite gives poor solubility in isopropyl alcohol and methanol.The percentage of sodium 1-arylethanesulfonate in crude sodium 1-arylethanesulfon-ates containing inorganic salt is about 11 %. By purification process, the percentage of sodium 1-arylethanesulfonates is more than 94 % with purification yields more than 98 %.