离子液体催化合成氯代脂肪醇聚氧乙烯醚的研究

Study on the Synthesis of Fatty Alcohol-polyoxyethylene Ether Chloride Catalyzed by Ionic Liquid

卤代脂肪醇聚氧乙烯醚是合成脂肪醇聚氧乙烯醚阳离子表面活性剂的中间体,其合成工艺研究对于开发多功能脂肪醇聚氧乙烯醚阳离子表面活性剂至关重要。传统的卤代反应多使用易挥发性有机溶剂,对环境污染大。目前的催化剂又存在反应时间长且副产物多等缺点。随着绿色清洁技术在工业和学术界得到广泛的关注,寻找更加绿色的溶剂和高效的催化剂成为焦点。作者以脂肪醇聚氧乙烯醚(AEO_3)和亚硫酰氯(SOCl_2)为原料,以离子液体1-辛基-3甲基咪唑溴盐([OMIM]Br)为催化剂和溶剂,合成了氯代脂肪醇聚氧乙烯醚(AEO_3-Cl)。研究了反应温度、反应时间、亚硫酰氯用量和离子液体用量对脂肪醇聚氧乙烯醚转化率的影响,并用红外光谱(FTIR)和核磁共振氢谱(1HNMR)对产物结构进行表征。研究结果表明,当n(AEO_3)∶n(SOCl_2)∶n([OMIM]Br)=1∶1.3∶1,反应温度为25℃,反应时间为30 min时,脂肪醇聚氧乙烯醚转化率达到99%。以正己烷为萃取剂,产物能够从反应混合液中萃取出来。该离子液体可以重复使用6次,转化率无明显降低,说明其具有较好的重复使用性能。此外,推测离子液体1-辛基-3甲基咪唑溴盐咪唑环上C^2位质子与脂肪醇聚氧乙烯醚的羟基氧形成氢键,降低了反应能垒,使反应具有良好的反应速率和选择性。因此,离子液体对该卤代反应具有很好的催化活性,且离子液体不易挥发,具有环保、无毒性等优点。

The cationic surfactant of fatty alcohol-polyoxyethylene ether is a multi-functional surfactant,which played an important role in the industry of detergent,textile and so on. Fatty alcohol-polyoxyethylene ether chloride( AEO_3-Cl) is the intermediate to synthesize the cationic surfactant of fatty alcohol-polyoxyethylene ether. The traditional halogenating reactions are always used the volatile organic solvents,which have great pressure to the environments. In addition,the drawbacks of those catalysts in halogenating reactions,such as,long reaction time and many by-products,are need to be solved. However,as the introduction of cleaner technologies has become a major concern throughout both industry and academia,the search for alternatives to the most damaging solvents and excellent catalysts has become a high priority. AEO_3-Cl was synthesized via halogenation reaction of reactants fatty alcohol-polyoxyethylene ether( AEO_3) and thionyl chloride( SOCl_2) which was catalyzed by ionic liquid 1-octyl-3-methylimdazolium bromide( [OMIM]Br). The effects of reaction temperature,reaction time,amount of SOCl_2 and the amount of [OMIM]Br on conversion rate of AEO_3 were investigated. The structure of the synthesized product was characterized by Fourier Transform Infrared Spectroscopy( FTIR) and H Nuclear Magnetic Resonance( 1HNMR). The results showed that [OMIM]Br is an effective catalyst for the reaction in room temperature and the conversion rate of AEO3 is reaching over 99%,with the following optimum reaction conditions of n( AEO_3) ∶ n( SOCl_2) ∶ n( [OMIM]Br) =1∶ 1. 3∶ 1( molar ratio),the reaction temperature 25 ℃ and reaction time 30 minutes. The product was separated from the reaction mixture by extraction using n-hexane followed by the evaporation of n-hexane. The catalysts could be re-used for six times without obvious decreases of conversion,which showed that the catalysts have good recycling performances. In addition,it was suggested that the C^2-H at-om in [OMIM]Br could form hydrogen-bond with oxygen atom in hydroxyl group of AEO_3,which reduced the reaction barrier,therefore led to high reaction rate and selectivity of the reaction. In summary,the [OMIM]Br has an excellent catalytic effect on the reaction. Notably,the [OMIM]Br is a nonvolatile compound,which have the advantages environmental friendly and nontoxicity.