Heat capacities of nine ionic liquids were measured from (293 to 358) K by using a heat flux differential scanning calorimeter. The impact of impurities (water and chloride content) in the ionic liquid was analyzed to estimate the overall uncertainty. The Joback method for predicting ideal gas heat capacities has been extended to ionic liquids by the generation of contribution parameters for three new groups. The principle of corresponding states has been employed to enable the subsequent calculation of liquid heat capacities for ionic liquids, based on critical properties predicted using the modified Lydersen-Joback-Reid method, as a function of the temperature from (256 to 470) K. A relative absolute deviation of 2.9 % was observed when testing the model against 961 data points from 53 different ionic liquids reported previously and measured within this study.

. Data 2008, 53, 716-726. Page 722. Equations 6 and 7 are wrong, and the following equations must be used in order to obtain a comparable relationship with eq 4. These errors are typographical and do not influence the calculations and conclusions claimed in this article.V* [C 4 where A i are the coefficients obtained by eq 4 and Φ [C 4

The thermal conductivities of 11 ionic liquids were determined, over the temperature range from 293 K to 353 K, at atmospheric pressure, using an apparatus based on the transient hot-wire method. For each of the ionic liquids studied, the thermal conductivities were found to be between (0.1 and 0.2) W·m-1·K-1, with a slight decrease observed on increasing temperature. The uncertainty is estimated to be less than ± 0.002 W·m-1·K-1. In all cases, a linear equation was found to give a good fit to the data. The effects of water content and chloride content on the thermal conductivities of some of the ionic liquids were investigated. In each case, the thermal conductivities of the water + ionic liquid and chloride + ionic liquid binary mixtures were found to be less than the weighted average of the pure component thermal conductivities. This effect was adequately modeled using the Jamieson correlation. Chloride contamination at typical postsynthesis levels was found to have no significant effect on the thermal conductivities of the ionic liquid studied.

The density of ionic liquids (ILs) as a function of pressure and temperature has been modeled using a group contribution model. This model extends the calculations previously reported (Jacquemin et al. J. Chem. Eng. Data 2008) which used 4000 IL densities at 298.15 K and 600 IL densities as a function of temperature up to 423 K at 0.1 MPa to pressures up to 207 MPa by using described data in the literature and presented in this study. The densities of two different ionic liquids (butyltrimethylammonium bis(trifluoromethylsulfonyl)imide, [N1114][NTf2], and 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide, [C4mPyrro][NTf2]) were measured as a function of temperature from (293 to 415) K and over an extended pressure range from (0.1 to 40) MPa using a vibrating-tube densimeter. The model is able to predict the ionic liquid densities of over 5080 experimental data points to within 0.36 %. In addition, this methodology allows the calculation of the mechanical coefficients using the calculated density as a function of temperature and pressure with an estimated uncertainty of ± 20 %.

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The prediction of molar volumes and densities of several ionic liquids has been achieved using a group contribution model as a function of temperature between (273 and 423) K at atmospheric pressure. It was observed that the calculation of molar volumes or densities could be performed using the "ideal" behavior of the molar volumes of mixtures of ionic liquids. This model is based on the observations of Canongia Lopes et al. (J. Phys. Chem. B 2005, 109, 3519-3525) which showed that this ideal behavior is independent of the temperature and allows the molar volume of a given ionic liquid to be calculated by the sum of the effective molar volume of the component ions. Using this assumption, the effective molar volumes of ions constituting more than 220 different ionic liquids were calculated as a function of the temperature at 0.1 MPa using more than 2150 data points. These calculated results were used to build up a group contribution model for the calculation of ionic liquid molar volumes and densities with an estimated repeatability and uncertainty of 0.36 % and 0.48 %, respectively. The impact of impurities (water and halide content) in ionic liquids as well as the method of determination were also analyzed and quantified to estimate the overall uncertainty.

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Acetonitrile is regarded as a key solvent in the pharmaceutical industry. However, the volatility in acetonitrile supply in recent years, coupled with its relatively poor environmental profile, has presented significant challenges to its use in manufacturing processes and laboratories. This study investigates the importance of acetonitrile in the pharmaceutical industry and critically examines several options for reducing the exposure of the industry to future supply problems whilst also improving its life cycle management. The physicochemical properties of acetonitrile were compared with other typical process solvents and the Conductor-like Screening Model (COSMO) surfaces and sigma profiles were used to help explain the favourable solvation behaviour of acetonitrile. Several options for the replacement or recovery and recycle of acetonitrile were critically examined in the contexts of environmental, technical and economic feasibility. Azeotropic distillation was found to be the most likely approach to recovering acetonitrile from aqueous waste streams. Several potential breaking agents were assessed against a range of selection rules based on residue curve maps, determined using the Universal Functional Activity Coefficient (UNIFAC) method, and potential processing issues. A range of ionic liquids were screened via the predictive Conductor-like Screening Model for Realistic Solvation (COSMO-RS) approach and several promising candidates were identified. Experimental vapour-liquid equilibria studies were carried out, confirming the feasibility of ionic liquid-enhanced azeotropic distillation as a novel approach to acetonitrile recovery.