| Due to their excellent thermal and chemical properties,such as thermal stability,designability,and low vapor pressure,ionic liquids are widely used in various aspects of chemical or chemical engineering.One of the most important applications is the pretreatment of biomass.Studies have reported that the ability of ionic liquids forming hydrogen bonds directly determines their effect in biomass pretreatment.Therefore,it has become a popular research method to find ionic liquids that can form strong hydrogen bond interactions with biomass.Among them,hydroxyethylamine ionic liquids provide a good structure basis for the formation of hydrogen bonds due to the presence of single or multiple hydroxyl groups.Also,the synthesis step of this type of ionic liquids is simple,and there is no by-product formation.Thus,hydroxyethyl ionic liquids are suitable for large-scale application and show a bright prospect of industrializing biomass pretreatment.In order to get the regularities of physicochemical properties of hydroxyethylamine ionic liquids and broaden their potential application.A series of 2-hydroxyethylammonium sulfonate-based ILs were synthesized through proton transfer reaction and characterized by 1H and 13C-NMR as well as FT-IR.Their phase transfer behavior(Tm),initial decomposition point(Td),density(?),viscosity(?)and electrical conductivity(?)were also characterized.In addition,the dissociation constants(pKa)of synthesized ILs in aqueous solution were obtained by acid-base titration.All these reaults were discussed basing on the structures of ILs.At the same time,N-methyl-diethanaminium methanesulfonate([MDEA][mesy])displayed good ability to dissolve ligin in previous work.In order to have a better understanding about the structure-property relationship and facilitate the further potential application in the industry,it is necessary to obtain more data about its physicochemical property.In this work,the densities(?)and viscosities(?)of[MDEA][mesy]+ solvents(water,methanol,ethanol,n-propanol and isopropanol)mixtures were measured at the temperatures from(298.15 to 323.15)K in the full molar composition.The densities and viscosities data of these five binary mixtures were fitted by an empirical polynomial equation and Vogel-Fucher-Tammann(VFT)equation,respectively.Moreover,the excess molar volumes(VE)and viscosity deviation(??)of five binary mixtures were calculated and correlated by Redlich-Kister equation.In addition,apparent molar volumes(V?),apparent molar volume in infinite dilute(V??)and partial molar volume(V)of[MDEA][mesy]and solvents were also calculated and all these change laws were discussed in terms of the structure and interaction of binary mixtures.What's more,1-butyl-3-methylimidazolium chloride([Bmim]Cl)and its binary or ternary systems also showed good biomass dissolution.As an intermediate compound,it plays an important role in the synthesis of other more complex imidazole ionic liquids.However,the absence of the ionic liquid standard has brought considerable obstacles to experimental and quantitative analysis.Therefore,in this paper,combined with the research work of the predecessors,[Bmim]Cl crystals were obtained by controlling the reaction conditions and purification methods.At the same time,the three-dimensional lattice and cell parameters were obtained by single crystal X-ray diffraction.The structures were confirmed by NMR,FT-IR and HR-MS,and the possibility of impurities in[Bmim]Cl was analyzed.The purity was analyzed by HPLC and ion titration and compared with the[Bmim]Cl produced by domestic and foreign manufacturers.The results indicated that the purity of synthesized[Bmim]Cl with the determination of HPLC peak area was more than 99.5%.This work laid the foundation for the preparation of the[Bmim]Cl standard. |
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