室温离子液体BMIGaCl4热力学性质研究

An ionic liquid （IL） BMIGaCh was prepared by directly mixing GaCl3 and 1-methyl-3-butylimidazolium chloride with molar ratio of 1/1 under argon atmosphere. The densities and surface tensions of this pure ionic liquid were determined in the temperature range of 268.15 to （338.15±0.1） K. A new theoretical model of ionic liquids, an interstice model, was applied to calculate the thermal expansion coefficient of IL BMIGaCh, a, and the magnitude order of its value calculated by the theory was the same as experimental one. Both Raman scattering and ab initio calculations indicate that GaCl4^- is the only species containing Ga in the ionic liquid BMIGaCl4.     

Molecular dynamics simulations of LiCl association and NaCl association in water by means of ABEEM/MM

Constrained molecular dynamics simulations have been used to investigate the LiCl and NaCl ionic association in water in terms of atom-bond electronegativity equalization method fused into molecular mechanics (ABEEM/MM). The simulations make use of the seven-site fluctuating charge and flexible ABEEM-7P water model, based on which an ion-water interaction potential has been constructed. The mean force and the potential of mean force for LiCl and NaCl in water, the charge distributions, as well as the structural and dynamical properties of contact ion pair dissociation have been investigated. The results are reasonable and informative. For LiCl ion pair in water, the solvent-separated ion pair configurations are more stable than contact ion pair configurations. The calculated PMF for NaCl in water indicates that contact ion pair and solvent-separated ion pair configurations are of comparable stability.     

Ion Pairing Kinetics Does not Necessarily Follow the Eigen-Tamm Mechanism

The most recognized and employed model of the solvation equilibration in the ionic solutions was proposed by Eigen and Tamm, in which there are four major states for an ion pair in the solution： the completely solvated state, 2SIP （double solvent separate ion pair）, SIP （single solvent separate ion pair）, and CIP （contact ion pair）. Eigen and Tamm suggested that the transition from SIP to CIP is always the slowest step during the whole pairing process, due to a high free energy barrier between these two states. We carried out a series of potential of mean force calculations to study the pairing free energy profiles of two sets of model mono- atomic 1：1 ion pairs 2.0：x and x：2.0. For 2.0：x pairs the free energy barrier between the SIP and CIP states is largely reduced due to the salvation shell water structure. For these pairs the SIP to CIP transition is thus not the slowest step in the ion pair formation course. This is a deviation from the Eigen-Tamm model.     

Measurement of the association constants through micro-Raman spectra of supersaturated lithium perchlorate droplets

High quality micro-Raman spectra of the LiClO4droplet with mass of nanogram scale were obtained at various concentrations from dilute to supersaturated state.From component band analysis of the v1-ClO4band,four peaks at 933.3,936.8,942.1 and950.7 cm 1were identified and assigned to free solvated perchlorate anion,solvent-shared ion pair,contact ion pair and complex ion aggregates,respectively.As expected,the signature of free solvated ClO4ion was observed to decrease in intensity with the increase in concentration.The intensity of the signature from solvent-shared ion pair was observed to rise with increase in concentration from 1.8 mol/kg to 5.0 mol/kg before decreasing as the concentration was further increased to 5.6mol/kg.Signatures of contact ion pair and of complex ion aggregates were shown to increase as the concentration was enhanced.Based upon the Eigen mechanism,we show that three association equilibria can be used to describe the transformations between free solvated perchlorate anion,solvent-shared ion pair,contact ion pair and complex ion aggregates.The overall association constant,K,and the stepwise association constants Ki(i=1 to 3)in the Eigen mechanism were determined separately with values of 0.025±0.003,0.023±0.002,0.068±0.033 and 0.686±0.174.Based on these constants,the electronic performance can be reasonably predicted by the optimum choice of electrolyte concentrations.     

Mean Activity Coefficients of KCI in the KCI-K2B4O7-H2O Ternary System at 308.15 K by EMF Method

The mean activity coefficients of KCI in a KCI-K2B407-H20 ternary system were experimentally determined at 308.15 K by the electromotive force measurement（EMF） via a battery cell without a liquid junction： K-ISEIKCI（m1）, K2B4O7（m2）ICI-ISE（ISE=ion selective electrode） in a total ionic strength of from 0.01 mol/kg to 1.00 mol/kg at different ionic strength fractions of KzB407 with yB=0, 0.200, 0.400, 0.600 and 0.800. K-ISE and CI-ISE presented a good Nernst effect, which implies that this method could be used to measure the activity coefficients of an electrolyte in the above system. The Harned rule was fitted to the experimental data, the Harned coefficients and the Pitzer single-salt ion parameters of KC1 were evaluated, and the relationship diagrams between the mean activity coefficient of KC1 and the ionic strength fraction（yB） were drawn. The mean activity coefficients of KCI（γ±KCI） decreased monotonically with the increase of I. The experimental results obeyed the Harned rule well.     

Two Typical Examples of Scaling Ionic Partition Scheme for Estimating Correlation Energy of A2 Type Molecules

Based on the calculation results of pair correlation energy contributions of the various electron pairs in Na2 and H2NNH2 systems and the application of the scaling ionic partition scheme for symmetrical A2 type systems, the total correlation energies of Na2 and H2NNH2 have been reproduced by using this simple scheme. The two results show that the absolute deviations are within an acceptable range of error, however, in this way, more than 90% of computational work can be saved. The most attractive result in present paper is that, in these two molecules the coefficients c1 and c2 in the estimation equation can be obtained by the proportion of correlation energy of A^- to that of A^ singlet system. Therefore, it is believed that the proposed ionic partition scheme for symmetrical A2 molecules would be very useful to estimate the correlation energies of large symmetrical molecules.     

离子液体催化丙烯腈氯化合成2,3-二氯丙腈

 Ionic liquids formed by imidazolium and pyridinium cations with Cl-, Br-, BF-4, and PF-6 anions were used for the catalytic synthesis of 2,3-dichloropropionitrile by the chlorination of acrylonitrile. The ionic liquids containing Cl- and Br- show good catalytic properties. The Cl- and Br- ions act as strong Lewis bases and molecular chlorine is activated by the induction effect of Cl- and Br-. Due to the stronger steric hindrance effect of the BF-4 and PF-6 anions, the chlorination of acrylonitrile is limited in the ionic liquids containing BF-4 and PF-6 anions.     

Reduction of Aldehydes and Ketones with Potassium Borohydride as Reductant

A series of aldehydes and ketones were reduced by potassium borohydride in an ionic liquid/water ([bmim]PF6/H2O) biphasic system to afford corresponding alcohol with high purity in excellent yields. The ionic liquid/water biphasic system could promote the chemoselectivity and the substituents such as nitro group and chlorine remained intact. Aromatic ketones were not as active as aromatic aldhydes and cyclic ketones owing to their higher steric hindrance. The ionic liquid could be recycled and reused. This protocol has notable advantages of no need of phase transfer catalyst and organic solvents, mild conditions, simple operation, short reaction time, ease work-up, high yields and recycling of the ionic liquid.     

Study on Electrochemical Copolymerization of Aniline and 3-Methylthiophene in HMIMBF4 Ionic Liquid and Its Properties

Electrochemical polymerization of aniline and 3-methylthiophene has been accomplished in 1-methylimidazium tetrafluoroborate （HMIMBF4） ionic liquid. Homopolymer and copolymers of aniline and 3-methylthiophene were obtained successfully. The copolymer was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The formation of copolymer has been confirmed by FT-IR and UV spectra. The atomic force microscope （AFM） was used for microstructural analysis. Both the homopolymer and the copolymer had the catalytic activity for the hydroquinone.     

The Standard Association Constant of Ion Pair [GaCl]~(2+)in the System of HCl+GaCl_3+H_2O

This paper reports the EMF(electromotive force) measurements of cell (A) without liquid junction at five temperatures from 278.15 to 318.15 K. Pt|H2(101.325kPa)|HCl(m1),GaCl3(m2),H2O|Ag|AgCl (A) The measurements on the system HCl+GaCl3+H2O was carried out in an appropriate concentration of hydrochloric acid when the concentration of hydrochloric acid is not lower than 0.13 mol/kg the hydrolysis of Ga3+ can be avoided or elimited1. The standard association constant, KAS ,…     

Synthesis and Characterization of Benzimidazolium Salts as Novel Ionic Liquids and their Catalytic Behavior in the Reaction of Alkylation

A new series of ionic liquids have been prepared containing benzimidazolium cation (abbreviated as Bim). These salts were characterized by DSC, NMR, elemental analysis and thermogravimetric analysis. They showed different properties compared to imidazolium cation due to the introduction of benzene ring. The alkylation of benzene/diphenyl ether with 1-dodecene was carded in C4eBimBr-AlCl3 ionic liquids showing high catalytic activity when the mole ratio of C4eBimB:AlCl3 was 1:2.     

Determination of Cationic Surfactant by Laser Thermal Lens Spectrometry

A novel method for the determination of cationic surfactant by laser thermal lens spectrometry was developcd,It was based on reaction between 1-hydroxy-2-(5-nitro-2-Pyri-dylazo)-8-aminonaphthaenc-3,6-disulfonic acid (5-NO2-PAH) and cationic surfactant to form 1:2 ionic association complex in a weakly basic medium (pH 9.44),The determination conditions and the mechanism were discussed,The method has been appliced to the analysis of wastewater and moat water samples.     

Bronsted Acidic Ionic Liquids as Efficient Catalysts and Mediums for the Synthesis of Half-esters:Structure-catalytic Selectivity Relationship

Bronsted acidic ionic liquids based on imidazolium cation were employed as efficient catalysts and mediums for the ring opening of phthalic anhydride to synthesize half-esters. Good yields, short reaction time and mild reaction condition were achieved. Lower acidity of ionic liquid resulted in higher catalytic selectivity in the synthesis of half-esters. The minimum-energy geometries of sulfonic acid-functionalized ionic liquids based on imidazolium cation revealed that their acidities and catalytic selectivity in the synthesis of half-esters were related to their structures.     

Immobilization of HX：[Hmim]X as Halogenating Agent, Recyclable Catalyst and Medium for Conversion of Alcohols to Alkyl Halides

HX is immobilized by reaction of halogen acid with methylimidazole, and the formed ionic liquid [Hmim]X was used as halogenating agent, catalyst as well as medium for conversion of alcohols to alkyl halides. Excellent yields were obtained. The halides produced could be easily separated from the reaction mixture via simple decantation, and the ionic liquid [Hmim]X could be regenerated conveniently by adding equivalent of halogen acids followed by removal of water.     

Laser photolysis of interaction of poly-guanylic acid (5'''') with anthraquinone-2-sulfonate

The electron transfer reaction between triplet anthraquinone-2-sulfonate and poly-guanylic acid (5') in CH3CN-H2O (97 : 3) has been investigated by 248 nm (KrF) laser flash photolysis. The transient absorption spectra and kinetics obtained from the interaction of triplet anthraquinone-2-sulfonate and poly[G] demonstrate that the primary ionic radical pair, radical cation of poly[G] and radical anion of anthraquinone-2-sulfonate have been detected simultaneously. The free energy changes in the process of the electron transfer were also calculated.     

Samarium—promoted Chemoselective Reduction of Aromatic Nitro Compounds in Ionic Liquid

The differently substituted aromatic nitro compounds were chemoselectively reduced by Sm/HOAc system in an ionic liq-uid medium to afford aromatic amines,Under these conditions the other substituents,such as -X,-CHO,-COOH,-CN,-NHTos and -alkyl,remained intact,the notable advan-tages of this reaction are its mild conditions ,simple operation,short reaction time,high yields and easy recycling of ionic liquid.     

Thermodynamics of Stability Constant of Binary Complex of Nicotinamide with Mn^＋＋

The stability constants of the binary complexes of Mn^2 with nicotinamide (NA) were determined from potentiometric pH titrations data at 15.0,25.0 and 35.0℃ and I = 0.1,0.2,0.4 molL^-1 (NaClO4). The formation of binary 1:1 , 1:2 NA-Mn complexes at three different temperatures and the influence of three different ionic strength on their stability were reported. The thermodynamic parameters (△f^0,△Sf^0,△Hf^0) for the complex formation reaction were estimated from stability constant at different temperatures.     

离子相互作用模型在HCl-LiCl-MgCl2-H2O体系20˚C时溶解度预测中的应用

Component solubility in HCl-LiCl-MgCl2-H2O system of high ionic strength at 20℃ was predicted by using the Pitzer＇s ion-interaction model. The results indicated that the model supplied a very good prediction of the component solubility of the system mentioned above. The values of parameters of β^0, β^1 and C^＊ of HCl, LiCl and MgCl2 were obtained from optimization of literature data, while those of θMN and ψMNX were calculated from a least-squares optimization procedure to couple activity coefficient with solubility data. According to the ion-interaction model, no additional parameters need to be determined for more complex systems. The study provided theoretical basis for the manufacture process, which was proposed by Gao and employed to extract LiCl and MgCl2·6H2O from salt lake brine.     

Synthesis,Characterization and Thermophysical Properties of Three Neoteric Solvents-Ionic Liquids Based on Choline Chloride

The authors prepared,characterized and preliminary studied the properties of some neoteric solvents-ionic liquids based on choline chloride,i.e.,three ionic liquids based on the eutectics of choline chloride（2-hydroxyN,N,N-trimethylethanaminium chloride） with,respectively,urea,malonic acid and citric acid.The obtained mixtures were clear and colorless ionic liquids at room temperature.The thermophysical properties,namely,density,viscosity,and electrical conductivity of these mixtures were investigated as a function of temperature within a range of 298-353 K.Correlations for the temperature dependence of the measured properties were generated and discussed in terms of Arrhenius theory.Finally the electrochemical windows of the eutectic liquids were determined.     

Study on Pair Correlation Energies of Isoelectronic Systems F^－, HF and H2F^＋

The intrapair and interpair correlation energies of F-, HF and H2F^ systems are calculated and analyzed using MP2-OPT2 method of MELD program with cc-PVSZ^* basis set. From the analysis of pair correlation energies of these isoelectronlc sysoterns, it is found that the 1sF^2 pair correlation energy is trans-ferable in these three isociectronic systems. According to the definition of pair correlation contribution of one electron pair to a system, the pair correlation contribution values of these three systems are calculated. The correlation contribution values of inner electron pairs and H—F bonding electron pair in HF molecule with those in H2F^ system are compared. The results indicate that the bonding effect of a molecule is one of the im-portant factors to influence electron correlation energy of the system. The comparison of correlation energy contributions in-cluding triple and quadruple excitations with those only includ-ing singles and doubles calculated with 6-311 G(d) basis set shows that the higher.excitation correlation energy contribution gives more than 2 % of the total correlation energy for these sys-tems.