Study On The Synthesis And Properties Of Two-alkyl Diphenylmethane

The subject of this study is a two-alkyl diphenyl methane disufosalt surfactant(Cn-DSDM). The reaction conditions, the characterization, the surface chemistry property and the application performance were researched in the paper.The Gemini surfactant ,two-alkyl diphenyl methane disufosalt surfactant, has been obtained through three steps. First,dialkyl diphenylmethane(C14-DDM)was produced by using diphenylmethane(DM) andα-tetradecene as raw materials in a Friedel-Crafts alkylating reaction in the presence of a catalyst. Then by means of sulfonation with chlorosulfuric acid and neutralization with NaOH aqueous solution,the final product was synthesized . After optimization, the best reaction conditions were showed as follows: in the alkylating reaction,diphenyl methane,α-tetradecene and anhydrous aluminum chloride (molar ratio l:2:0.1) reaction time is 6h and reaction temperature is 80℃(yield 87.52%) . In the sulfonation reaction,alkyl diphenylmethane,acid Chloride and chloroform (molar ratio l:4:2) reaction time is 40min and reaction temperature is 15℃(yield 85.26%). The structures of the final product was analyzed by IR, MS and HPLC.The air-liquid surface tension (γcmc) and the critical micelle concentration (cmc) of the dialkyl diphenyl methane sulfonate (DSDM) aqueous solution were measured by drop volume method at temperature of 313K. Theγcmc were lower in the 35.2 mN/m, 41.4mN/m and 46.7mN/m, and the cmc were lower in 2.04×10^-3mol/L, 4.47×10^-3mol/L and 8.03×10^-3mol/L. Compared to ordinary surfactants, the cmc of the DSDM is one order of magnitude lower, which show its good surface activity. And the interfacial tension of C14-DSDM solution (concentration 0.3%, which dissolved in the hardness 300 mg/L, salinity 6000 mg/L water)can reach 2.85×10^-2mN/m at 70℃, which is close to the ultra-low interfacial tension. And they also have good performance of solubilization capacity, emulsification, solution stability and other application performance.The electric conductivity of the C14-DSDM solutions was measured at 298K, 303K and 308.0K respectively. The results showed when the temperature increasing, the conductivity of C14-DSDM was increased, and the antiparticle binding K0 was decreased. The theoretical derivation of ionic strength showed that DSDM solutions is triple ionic intensity of anionic surfactants solutions. The thermodynamic data showed that the micellization process for the surfactant C14-DSDM is entropy driven.