ABSTRACT
A new group of BF3 complexing phosphate/phosphonate ionic liquids (ILs) [Emim][X(BF3)2] (X = dimethyl phosphate, diethyl phosphate, methyl phosphonate, and ethyl phosphonate) were synthesized and characterized. Key thermophysical properties of the new complex ionic liquids, including density, viscosity, conductivity, surface tension, solid-liquid phase transition, and thermal stability were determined and compared with those of [Emim][X]. Some other important thermophysical properties such as isobaric thermal expansion coefficient, molecular volume, standard molar entropy, and lattice potential energy were obtained from measured density data, and the free volume was estimated by a linear equation presented in this article, while critical temperature, normal boiling temperature, and enthalpy of vaporization were estimated from measured surface tension and density data. Furthermore, Fragility study shows that [Emim][X(BF3)2] could be considered as metallic glass-forming liquids, while [Emim][X] could be considered as extremely fragile liquids. The ionicity of [Emim][X(BF3)2] was predicted by Walden rule, and the result shows that these ILs fit well with Walden law. The key features of these complex ILs are their extremely low glass transition (-95.33~-98.46 â) without melting, considerably low viscosities (33.876~58.117 mPa·s), and high values of free volume fraction (comparable to [Omim][BF4], [Emim][NTf2], and [Emim][TCB]).
ABSTRACT
A new series of complex anion ionic liquids (ILs) [Emim][BF3X] (X = CH3SO3, EtSO4, HSO4, Tosylate) were synthesized and characterized by nuclear magnetic resonance, elemental analysis, differential scanning calorimetry analysis, and thermogravimetry. The physicochemical properties of these ILs, such as density, viscosity, conductivity, and surface tension, were measured and correlated with thermodynamic and empirical equations in the temperature range of 293.15-358.15 K under ambient conditions, and the thermal expansion coefficient, standard molar entropy, lattice potential energy, viscosity activation energy, surface enthalpy, and surface entropy were further calculated from experimental values. According to the temperature-dependent viscosity and conductivity, [Emim][BF3X] ILs follow the Walden rule, and they are classified as "good (or super) ionic liquids".
ABSTRACT
An efficient method for stereoselective synthesis of trifluorinated enol esters catalyzed by base was introduced. The DFT calculations and experimental results both supported the nucleophilic addition process. The protocol featured mild reaction conditions and showed a wide functional group tolerance. The one-pot simultaneous etherification and esterification of the salicylic acids further demonstrated the prospective synthetic application.
ABSTRACT
OBJECTIVE: To investigate the bronchial hyperreactivity (BHR) and pulmonary function in patients suffering from endobronchial tuberculosis (EBTB), and therefore to provide clues for early and correct diagnosis of EBTB. METHODS: Twenty-four patients with EBTB, proved by fiberoptic bronchoscopy, chest computerized tomography and biopsy, received measurements of pulmonary ventilatory function, airway resistance (Raw), and bronchial responsiveness test. The results were analyzed by t test and correlations. RESULTS: As many as 41.7% of the patients with EBTB were found to have BHR, which had never been recognized before. The patients with EBTB usually had severe cough (100%, 24/24), shortness of breath (54%, 13/24), and wheezing, but bloody sputum was found in only 21% (5/24), and so the patients tended to be misdiagnosed as having asthma, especially cough variant asthma. FEV(1%) in the group of EBTB with BHR was significantly higher than that in the group of EBTB without BHR (t = 2.345, P < 0.05). But there was no significant difference of FEV(1)/FVC%, MMEF%, V(75%) and Raw between the two groups. In the group of EBTB with BHR, FEV(1%) showed a negative correlation with BHR (r = -0.61, P < 0.05), but there was no remarkable correlation between the other pulmonary function parameters with BHR. CONCLUSION: BHR is present in a considerable number of patients with EBTB, and therefore attention should be paid to the differential diagnosis of EBTB and cough variant asthma.
