Synthesis And The Physical Chemistry Properties Of Taurine Ionic Liquid[C_nmim]Tau(n=3,4)

Nowadays,ionic liquids have the history of nearly 100 years,the third generation of ionic liquids is called task-specific ILs.Researchers have paid more attention to ILs,they have been used in many fields.The properties of ionic liquids can be coordinated by combining different cations and anions,ILs could be designed.In this paper,we use neutralization method to prepare taurine ionic liquids.Firstly,1-methylimidazole was combined with 1-chloropropane and 1-chlorobutane respectively,[C_nmim]Cl(n=3,4)could be obtained.1-alkyl-3-methylimidazolium hydroxide([C_nmim][OH])(n=3,4)were synthesized from[C_nmim]Cl(n=3,4)by using the activated anion-exchange resin.At last,taurine was mixed with the([C_nmim][OH])(n=3,4)respectively,then the final product[C_nmim]Tau was obtained.After purification,the ionic liquids were characterized by ~1H NMR.Learning the properties of ionic liquids is the basic for the usage of ILs.The properties of ILs are quite special.During engineering designing process,the prediction of ILs’data is needed.In this paper,the densities,surface tension and refractive index of pure taurine ionic liquids were measured,a method for estimating surface tension was provided.Taurine ionic liquids can easily form strong hydrogen bonds with water,the standard addition method(SAM)was used to determine the densities of pure taurine ILs.Density is the important volumetric properties.According to densities,the coefficient of thermal expansion and the molecular volume can be measured.On the basic of Glasser’s theory,standard entropy and lattice energy can be calculated.Compared with other substance,the lattice energy of ILs is relatively small.Because of this,at room temperature,ILs are molten salts.The surface tensions of[C_nmim]Tau(n=3,4)were measured by forced bubble method,SAM is also used.According to the values of surface tension,the surface entropy and surface energy of taurine ionic liquids can be obtained.The values of ILs’surface energy are similar to them of organic solvents.The coefficient of thermal expansion can be estimated from surface tension.On the basic of E?tv?s equation,critical temperature can be obtained.By using Rebelo’s theory and Kabo’s theory respectively,enthalpy of vaporization can be estimated.A new concept called molar surface Gibbs free energy was provided.E?tv?s equation has been improved by this concept,and a new E?tv?s equation was developed.The molar surface entropy and the molar surface enthalpy can be deduced from the new E?tv?s equation.The molar surface Gibbs free energy can also be used to predict surface tension.Similar to the determination of densities and surface tensions,SAM is also used to measure the refractive index.The molar polarization R_m and polarization coefficient?_p were calculated.