支链烷基苯磺酸钠的表征及表面性质的测定

为了研究支链烷基苯磺酸钠的构效关系,以苯为初始原料经酰化、格氏反应、氢化还原、磺化中和等4步合成了4种支链烷基苯磺酸钠。支链总碳原子数为16,苯环连接位置分别在支链的2,4,6和8位。它们的结构分别为:(A)CH3(CH2)13CH(CH3)C6H4SO3Na;(B)CH3(CH2)11CH(C3H7)C6H4SO3Na;(C)CH3(CH2)9CH(C5H11)C6H4SO3Na;(D)CH3(CH2)7CH(C7H15)C6H4SO3Na。经核磁和红外光谱确定了化合物的结构,用两相滴定方法确定了产物中烷基苯磺酸钠的质量分数均大于99%。用Wilhelmy-Plate法测定了4种支链烷基苯磺酸钠在30℃下的临界胶束浓度CMC(mmol/L)以及临界胶束浓度下的表面张力γCMC(mN/m)。CMC和γCMC值分别为:(A)0 112,35 96;(B)0 232,35 05;(C)0 420,33 86;(D)0 708,31 47。根据Gibbs吸附公式求出饱和吸附量Γm、饱和吸附面积Am以及表面压πCMC。发现随着苯环在烷基链上连接位置由2变化到8,CMC增大,γCMC降低。采用电导法测定了4种支链烷基苯磺酸钠的临界胶束浓度,其结果与表面张力法的测定结果一致。采用两种基于辛醇/水分配系数的方法预测了4种表面活性剂的CMC,结果表明,考虑了支链化的CMC与实验结果符合较好。

Characterization and Surface Property Measurement of Sodium Branched Alkylbenzenesulfonates

Four kinds of sodium branched alkylbenzenesulfonates were synthesized by four-step process,involving Friedel-Crafts reaction,Grignard reaction,reducation and sulfonation,to investigate the structure-activity relationship.Benzene was used as the stating material in the synthesis.In the surfactants, hydrophobic alkyl chain is hexadecane and benzene ring substitutes at positions 2, 4, 6 and 8 of hexadecane.Their structures are as follows:(A)CH_3(CH_2)_(13)CH(CH_3)C_6H_4SO_3Na,(B)CH_3(CH_2)_(11)CH(C_3H_7)C_6H_4SO_3Na,(C)CH_3(CH_2)_9CH(C_5H_(11))C_6H_4SO_3Na and (D)CH_3(CH_2)_7CH(C_7H_(15))C_6H_4SO_3Na.The structures of these surfactants are identified by ~1HNMR and IR.The mass fractions of sodium branched alkylbenzenesulfonates in all products are more than 99%,determined by two-phase titration method.The critical micelle concentration (CMC) and the surface tension (γ_(CMC)) of four surfactants were measured at 30 ℃ in aqueous solutions by Wilhelmy-Plate method.The values of CMC (mmol/L) and γ_(CMC)(mN/m) are (A)0.112,35.96,(B)0.232,35.05,(C)0.420,33.86 and (D) 0.708,31.47,respectively.Γ_m,A_m and π_(CMC) are obtained from the Gibbs formula.It is found that CMC increases as benzene ring shifts from position 2 to 8 and γ_(CMC) decreases at the same time.The values of CMC obtained by measuring the electrical conductivity are consistent with those obtained by Wilhelmy-Plate method.Moreover, two sets of values of CMC are obtained by using octanol/water partition coefficients in two methods.The results show that the values obtained by considering the branching are consistent with those obtained in experiments.