烷基链改变对吡啶类离子液体的性能影响

离子液体是一类新型软功能材料,在多相催化、萃取分离、材料制备等领域具有重要的研究意义.本文基于吡啶环上烷基链的分子结构设计,分别以溴代烷(CnH2n-1Br,n=4,8,12)、吡啶和六氟磷酸钾为反应物,获得了3种不同烷基结构的疏水性吡啶类离子液体Cnpyr]PF6].研究表明,直链烷基吡啶类离子液体的熔点随着吡啶环上烷基链的增长,出现先降低后升高的趋势,其热分解温度在370℃左右.在室温下测定了Cnpyr]PF6]离子液体的电导率,通过非线性最小二乘法对测得数据进行拟合,得到了Cnpyr]PF6](n=4,8,12)的电导率与浓度之间的函数关系,其拟合的标准偏差分别为0.002 39μs/cm,0.004 47μs/cm,0.004 78μs/cm.最后,Cnpyr]PF6]属于典型的疏水性离子液体,烷基链长度的改变对溶解性的影响相对较小.

Impact on properties of different alkyl chain pyridine ionic liquids

Hydrophobic ionic liquid is a new class of soft functional materials.Based on the design of the alkyl chain structure on the pyridinium ring,n-alkyl pyridinium ionic liquidsCnpyr]PF6]（n=4,8,12）was obtained by a two-step method.Research shows that the melting points of alkyl pyridinium ionic liquids has a first reducing,then rising trend,with the increase of the alkyl chain on the pyridinium ring.And it indicates that the thermal decomposition temperatures of ionic liquids are near 370℃.Moreover,the conductivities ofCnpyr]PF6]were determined by the conductivity meter,and the data of conductivities were fitted by nonlinear least square method,fitting standard deviations ofCnpyr]PF6]（n=4,8,12）are 0.002 39μs/cm,0.004 47μs/cm,0.004 78μs/cm.Finally,the results show thatCnpyr]PF6]（n=4,8,12）are the hydrophobic ionic liquids,and the influence of the different alkyl chains on the solubilities ofCnpyr]PF6]is relatively small.