Synthesis And Performance Of N,N-dimethydocecyl Sulfobenzyl Betaine

Due to its excellent properties, sulfobetaines have recently attracted increasingattention. In this paper, we investigated a p-sulfobenzyl ammonium inner salts, that is,N,N-dimethyldocecyl sulfobenzyl betaine (DBSB) by sulfonation of thedodecyldimethylbenzylammonium chloride (DBAC) directly, which differ from thepreviously mentioned sulfobetaines in that a benzyl linkage bridges the quaternarynitrogen and sulfonate group rather than a two-carbon, three-carbon, or four-carbonahphatic linkage. The reaction conditions were optimized in order to meetindustrialized needs. The performance of DBSB mixed with sodium lineardodecylbenzene sulfonate (LAS), soap and lauramidopropyl hydroxy sulfobetaine(HSB) were studied, respectively. Specific content and the main conclusions are asfollows:DBSB was prepared from DBAC using 1, 2-dichloroethane as solvent, the crudeproducts were purified by recrystallization, and the molecule structure was confirmedby infrared spectroscopy (IR), high performance liquid chromatography (HPLC),electro-spray ionization mass spectrometry (ESI–MS) as well as 1H nuclear magneticresonance spectroscopy (1HNMR). In order to determine process conditions for thesynthesis of DBSB, the amount of sulfonating agent, reaction temperature andreaction time are analyzed and discussed. Under the optimized reaction conditions:when mDBAC/V(CH2CH2Cl2) = 0.125 g/mL, n(HSO3Cl):n(DBAC) = 3.8, at 60 oC for 20 h,the average conversion rate of DBAC is 97.16%.The physicochemical properties, anti-hard water performance, and someapplication performance of the DBSB/LAS and DBSB/soap binary systems werestudied. It was found that when the content of LAS is above 30%, the Krafft point ofDBSB dropped almost 70 oC, which greatly improved the solubility of DBSB at lowtemperature. Besides, the binary solutions of DBSB/LAS behave synergistically insurface tension reduction effectiveness, foaming as well as wetting. The calciumtolerance of pure LAS was enhanced 6 times with increasing concentration of DBSBto 15%. The detergency of both DBSB/LAS and DBSB/Soap systems were alsosuperior to the individuals, more importantly, DBSB can significantly improve theanti-hard water performance of LAS and Soap. Therefore, the DBSB can be regardedas potential compositions for non-phosphorus detergent or complex soap.When the total concentration of surfactant was 0.1 wt%, adding 1% isoamylalcohol (vol %), the dynamic interfacial tension of DBSB/HSB system with differentelectrolyte concentrations were investigated at 45 oC. The results suggesting that,when the concentration of NaCl was 3%, the interfacial tension of DBSB/HSB systemwas relatively low (0.42 mN/m), however, there is no trend of forming ultra-lowinterfacial tension. More interfacial properties of DBSB remains to be further studied.