Synthesis And Performances Of Novel Surfactants Oil-based Diphenyl Sulifde Sulfonates

Sodium linear alkyl benzene sulfonate （LAS） has low cost performance and poor abilityof resisting hard water, whereas alkyl diphenyl ether sulfonate has some better performances,such as excellent surface activity and strong electrolyte resistance, due to the later containingdiphenyl ether structure instead of benzene ring in the molecule of LAS. In this paper, theoxygen bridging atom in the sodium alkyl diphenyl ether sulfonate was further replaced bysulfur bridging atom, and then three novel oil-based surfactants were synthesized, that is,sodium dodecyl diphenyl sulfide monosulfonate （DSM）, disodium dodecyl diphenyl sulfidedisulfonate （DSD） and disodium didodecyl diphenyl sulfide disulfonate （DDSD）. Futhermore,in order to simplify the above-mentioned synthesis course of oil-based surfactants,dodecanoyl diphenyl sulfide （D_nS） and didodecanoyl diphenyl sulfide （DD_nS）, theFriedel-Crafts acylation products of diphenyl sulfide were directly sulfonated and neutralizedwithout carbonyl reduction in advance to synthesize another two novel oil-based surfactantssodium dodecanoyl diphenyl sulfide monosulfonate （D_nSM） and disodium dodecanoyldiphenyl sulfide disulfonate （D_nSD）. Finally, the structure-performances of these noveloil-based surfactants were investigated.At first, D_nS and DD_nS were synthesized from lauric acid, a component from natural fatsand oil as renewable raw materials, and diphenyl sulfide by Friedel-Crafts acylation. Theinfluence of the dosage of catalyst AlCl3in the Friedel-Crafts acylation is investigated, andthe results showed that the yield of D_nS is as high as98.0%when n（AlCl3）: n（lauroyl chloride）=1.5:1. Futhermore, D_nS and DD_nS were respectively reduced to dodecyl diphenyl sulfide（DS） and didodecyl diphenyl sulfide （DDS） by Clemmensen reduction. Finally, theintermediates D_nS, DS and DDS were sulfonated by chlorosulfonic acid in controlled dosages,and followed by neutralization with sodium hydroxide to synthesize five novel oil-basedsurfactants （CAS numbers are unavailable）, D_nSM, D_nSD, DSM, DSD and DDSD,respectively. The suitable sulfonation conditions to synthesize D_nSM were found as follows:n（ClSO3H）: n（D_nS）=1.75:1and post-sulfonation period for4h at60oC, the yield of D_nSMcould reach98.2%. All the four intermediates and five surfactants were separated and purifiedfrom the reaction mixtures and their chemical structures were identified by means of FT-IR,1H-NMR and ESI-MS, respectively; and the contents of some target products were detectedby HPLC and determined by area normalization method.The experimental results of Krafft points showed that D_nSM, D_nSD, DSD and DDSDhave excellent water solubility at low temperature （TK<0oC）, but TKof DSM is95oC, so thesurface activities, electrolyte resistance, calcium stability and lime soap dispersing power of the former were investigated. The experimental results of the surface activities at25oCshowed that DDSD has poor ability of reducing both surface tension and cmc; D_nSM anddodecyl diphenyl ether monosulfonate（C12-MAMS） have similar γcmcvalue, approximate37mN/m, and the γcmcvalues of D_nSD, DSD and dodecyl diphenyl ether disulfonate （C12-MADS）are comparative, which indicated that the surface tension reduction of these diphenyl sulfidesurfactants are ordinary. The cmc value of D_nSM is0.438mmol/L, that is a little lower thanthat of C12-MAMS but approximately one third of that of LAS; and the cmc values of D_nSD,DSD are not much different from the cmc of C12-MADS; which indicated that sulfur atominstead of oxygen atom makes the cmc little bit lower.The electrolyte resistances of D_nSM, D_nSD DSD and DDSD were also measured.Compared with LAS, DDSD has the same poor electrolyte resistance, but D_nSM possessesexcellent resistance to alkali, hard ion, neutral electrolyte and acid, and it can soluble inaqueous solution of9.7%（wt%） NaOH,14.5%（wt%） CaCl₂,24.3%（wt%） NaCl and30.9%（wt%） HCl, respectively; D_nSD also possesses excellent resistances to neutralelectrolyte, acid and hard ion; DSD possesses outstanding resistances to neutral electrolyteand acid. All these facts proved that these three novel oil-based diphenyl sulfide surfactantscould be used in a variety of high levels of strong electrolytes environment. Furthermore, theexperimental results of the calcium stability and lime soap dispersing power showed that thecalcium stability and lime soap dispersing power of DDSD are still poor, just like its poorsurface activities; the calcium stability of D_nSM, D_nSD and DSD is greater than1800mgCaCO3/L, which is commonly regarded as the standard of a hard water resistant surfactant.And the LSDP of D_nSM, D_nSD and DSD is26%,32%,7.5%, respectively, which proves theyare good or excellent lime soap dispersants. Therefore, these three novel oil-based surfactantshave good applied prospects.