三相转移催化合成1,2-乙二硫醇

制备出了一系列大孔聚苯乙烯-二乙烯苯(PS)接枝季铵盐,并以此为三相转移催化剂,用于催化由1,2-二溴乙烷和70%硫氢化钠为原料合成1,2-乙二硫醇的反应。考察了接枝叔胺种类、反应温度、催化剂用量、反应物摩尔比、溶剂用量、硫氢化钠水溶液的pH值及浓度、催化剂研磨与否等因素对合成反应的影响,建立了适宜的反应条件:以0.1mol1,2-二溴乙烷计,n(二溴乙烷)︰n(硫氢化钠)=1︰2.2、PS接枝三乙胺季铵盐0.7g、甲苯8.6mL、70%硫氢化钠浓度10mol/L、采用4mol/L氯化铵水溶液酸化硫氢化钠至pH≈12、反应温度75℃、反应时间5.5h。在此条件下1,2-二溴乙烷转化率99%以上,1,2-乙二硫醇的收率50%～55%。催化剂可循环使用5次。

Synthesis of 1,2-ethanedithiol with tri-phase phase transfer catalysis method

A series of macroporous polystyrene grafted with quartemary ammonium salts as tri-phase phase transfer catalysts were prepared for the synthesis of 1,2-ethanedithiol. Factors that influence the reaction were investigated including the type of tertiary amine, reaction temperature, amount of catalyst, molar ratio of 1,2-dibromoethane to sodium hydrosulfide, amount of solvent, pH value and concentration of aqueous solution of NaHS, grinding catalyst or not etc. Proper reaction conditions were obtained based on 0.1mol 1,2-dibromoethane as n(1,2-dibromoethane) : n(NaHS)=1 : 2.2, polystyrene grafted with triethylamine 0.7 g (containing quartemary ammonium salt 0.002mol) , toluene 8.6 mL, pH value of NaHS aqueous solution adjusted by NH_4Cl to about 12, concentration of NariS aqueous solution 10mol/L, reaction temperature 75℃, reaction time 5.5 h, under which the conversion of 1,2-dibromoethane is higher than 99% and yield of 1,2-ethanedithiol is 50%～55%. The catalyst can be used for five times with no obviously negative effect.