Synthesis And Characterization Of A Serie Of P-alkyl Isopropylbenzene Sulfonates

Nine kinds of p- alkyl isopropylbenzene sulfonates with different chain length and the benzene ring attached to different position of the alkyl chain were synthesized through five-step process, involving Friedel-Crafts reaction, Grignard reaction, reducation, sulfonation and neutralization. Some materials like isopropyl benzene and different fat acid were used as the starting materials. The structures of the intermediates and final products were proved by FT-IR, ESI-MS, ¹³C NMR and ¹H NMR to be right as expected,and the boiling points and refractive indexes of intermediates were measured.The surface tension of dilute aqueous solution of surfactants was measured at 25℃by Drop-volume method, then cmc andγ_cmc were determined. These results indicated that as the benzene ring moving from the end to the middle of the long alkyl chain, the values of cmc increased, but the values ofγ_cmc reduced; as the carbon number of alkyl chain increasing, the values of cmc andγ_cmc both reduced.The interfacial tension between nine dilute aqueous solutions of surfactants and a serie of n–alkanes were studied by Spinning drop method, whose nmin were determined, taking C₁₆-3S,C₁₆-5S,C₁₆-7S as examples, then the effect of different concentrations of surfactants, sodium chloride, sodium hydroxide on the interfacial tension were studied. The results showed that the values of C₁₂-1S,C₁₂-3S,C₁₄-3S,C₁₄-5S,C₁₄-7S were all less than 7; the values of C₁₂-5S,C₁₆-3S,C₁₆-5S,C₁₆-7S were respectively 8,8,8,11; as the surfactant concentration increasing, at first the interfacial tension decreasing, achievinging a lowest value then increasing; C₁₆-3S,C₁₆-5S,C₁₆-7S all had optimum salinities, and the interfacial tension could decrease to 10-3mN/m degree under the optimum salinities, and as the benzene ring moving from the end to the middle of the long alkyl chain, the values of optimum salinities a little increasing; the optimum basicity of C₁₆-3S was 0.2%, and the optimum basicities of C₁₆-5S,C₁₆-7S were 0.4%, and the interfacial tension of C₁₆-7S under the optimum basicity was the lowest.