【作者】 王泽云；

【导师】 杨锦宗； 张淑芬；

【作者基本信息】 大连理工大学 ， 应用化学， 2010， 博士

【摘要】 甜菜碱两性表面活性剂具有良好的配伍性、生物降解性、低刺激性及丰富的泡沫等优点,但是与其它类型表面活性剂相比,其高昂的成本在很大程度上限制了其在更加广泛领域的应用。本文采用价格低廉的天然油脂水解产物脂肪酸为原料,经氯代、胺化反应直接合成了α-长链烷基甜菜碱两性表面活性剂,与传统甜菜碱表面活性剂合成工艺路线相比,本合成方法大大降低了生产成本,产品更加安全环保、易于生物降解。短碳链羧酸的氯代反应比较容易进行,但是长链脂肪酸的氯代反应存在收率低、副反应多等缺点。本文采用外加自由基捕捉剂和质子酸催化的方法,提高了氯代反应的选择性和反应速率,得到系列α-氯代长链脂肪酸的收率达96%以上。采用气相色谱、氯含量分析和红外光谱等方法对产品进行了表征。以α-氯代长链脂肪酸为原料与三甲胺反应合成α-长链烷基甜菜碱的方法未见有文献报道。本文通过对三甲胺与α-氯代长链脂肪酸摩尔配比、反应温度及反应器形式等因素的研究,发现α-长链烷基甜菜碱的收率可以达到92.5%。采用电渗析的方法对合成的α-长链烷基甜菜碱粗品进行了脱盐提纯,脱盐率达到99%以上。采用化学分析、元素分析、红外光谱、核磁共振及质谱等方法对产品进行了表征。对α-氯代十二酸与三甲胺亲核取代反应的动力学进行研究,确定反应机理为SN2取代反应,并建立了反应的速率方程。溶剂对α-氯代十二酸与三甲胺的亲核取代反应有显著影响。对于极性质子溶剂,溶剂极性的增大,有利于过渡态的电荷分离,过渡态能量降低,反应速率增加；极性非质子溶剂中,偶极正端藏于分子内部,对于亲核试剂很少溶剂化,有利于提高反应速率。对α-长链烷基甜菜碱的表面活性与溶液胶体性质的研究结果表明,与同碳链的其它类型表面活性剂相比,α-长链烷基甜菜碱具有较高的表面活性和优良的溶液胶体性质；pH值对溶液的表面张力和临界胶束浓度有较大影响,在表面活性剂的等电pH区域,具有最高的表面活性、最低的临界胶束浓度和胶束化自由能；与阴离子表面活性剂十二烷基硫酸钠的混合溶液在表面张力降低效率和临界胶束浓度降低方面都有显著的协同效应。对比了α-长链烷基甜菜碱与BS-12的应用性能。结果表明,α-长链烷基甜菜碱的泡沫、润湿、去污等综合性能优于BS-12。在皂类产品中的应用实验表明,α-长链烷基甜菜碱对皂的泡沫、润湿、抗硬水及刺激性均有明显改善,是一种性能优良、成本低廉的两性表面活性剂。更多还原

【Abstract】 Betaine type zwitterionic surfactants have the unique properties such as desirable synergism effect with a wide variety of ionic and nonionic surfactants, good degradability, rather low irritation, and high foam stability. However, their wider application in industry is limited by their high production cost. In this paper, the long-chain alkylbetaine surfactants were prepared by simple and effective two-step route using cheap natural long fatty acids as raw material, and thus the cost of the alkylbetaine surfactants was greatly reduced in comparison with conventional synthesis route. In view of the green preparation method, the long-chain alkylbetaine surfactants are biologically safe, be environmentally friendly and easy to be biologically degraded.The synthesis of a-monochlorocarboxylic acids with short carbon chain has been developed successfully. Nevertheless, it is reported that the yield of long-chain a-chlorocarboxylic acids was yet low and there existed many byproducts due to the relative low reaction activity. In the present work, the selectivity and reaction rate were grately improved by using chlorosulfuric acid as catalyst and molecular oxygen as the radical scavenger, resulting the yield of above 96% under the optimized conditions. The structure of a-chloro-fatty acid was characterized by chlorine element analysis, infrared spectrum and nuclear magnetic resonance.The synthesis of a-long-chain alkylbetaine via aminolysis of a-monochloro-fatty acid with trimethylamine was investigated. The effects of molar ratio of reactants, reaction temperature and the type of reactor on the yield of a-long-chain alkylbetaine have been studied. Experimental results showed that the reaction can give a good yield (ca.92.5%). The crude product is purified by the electrodialysis desalination with the efficiency of 99%. The structure of the a-long-chain alkylbetaines was characterized by chemical analysis, element analysis, infrared spectrum, nuclear magnetic resonance and mass spectrometry.Kinetics and mechanism of the reaction of a-monochloro-fatty acid with trimethylamine were investigated. The experimental results suggested that the reaction proceeded through the SN2 mechanism. The rate equations were derived empirically. The experimental results also showed that the solvent effect on the reactivity was significant. In the case of protic polar solvents, the increase in solvent polarity favored the dispersal of charges at the transition state, therefore the reactivity was increased. The dipolar aprotic solvents can promote the SN2 reaction rate greatly because hydrogen-bonding interactions with anions did not take place in dipolar aprotic solvents. The solvation degree of nucleophiles was lower by dipolar aprotic solvents than by protic solvent, which benefited the generation of transition state.The surface tension and physicochemical properties of a-long-chain alkylbetaine revealed that its surface activity was higher than that of the other surfactants with the same chain length. The system presented the lowest surface tension, critical micelle concentration(cmc) and standard Gibbs energy of micellization when the pH of a-long-chain alkylbetaine solution approached isoelectric point. The mixed solutions ofα-decylbetaine and sodium dodecyl sulfate behaved synergistically in both surface tension reduction and mixed micelle formation.Some applied performances of a-long-chain alkylbetaines were examined and compared with that of BS-12. The results suggested that a-long-chain alkylbetaines exhibited better foaming performance, wettability and decontamination ability than BS-12. Moreover, the application performance of soap with addition of a-long-chain alkylbetaine was investigated. The results showed that the the foam performance, wettability, hard water-resistance and decreasing skin irritation of the soap were improved significantly by adding a-long-chain alkylbetaines. This indicates that a-long-chain alkylbetaine is a kind of high performance and low-cost zwitterionic surfactant.更多还原