Ionic Liquids (ILs) are important in many fields including alternative energy, solvent chemistry, and propulsion, but in many cases they have not been fully characterized and understood. Recently, we have determined the gas phase acidity of 2-nitropyrrole, 3-nitropyrrole, 3-nitropyrazole, 4-nitropyrazole, 2-nitroimidazole, and 4-nitroimidazole both experimentally using the extended kinetic method and theoretically using electronic structure calculations. The species studied are commonly found as the anionic component in several novel ionic liquids, and “it is the nature of the anionic component which controls the gross characteristics of the system.” [1] In addition, the basicity of ionic liquids is shown to be dominated by the gas phase basicity of the anion. [2] Extended kinetic method experiments were carried out using a 4000 Q Trap (AB Sciex) triple quadrupole instrument. The anionic proton bound heterodimers examined were generated from solutions of concentrations from 5-35 µM using an electrospray ion source. The series of reference acids used during this study were carboxylic acids. Electronic structure calculations were executed using the Gaussian 09 suite of programs to determine theoretical gas phase acidities. The gas phase acidities of the reference carboxylic and unknown azole acids were determined by optimizing reactant and product structures at the B3LYP/aug-cc-pVTZ level of theory. Single point calculations using the same basis set were also run at the B3P86/aug-cc-pVTZ and MP2(full)/aug-cc-pVTZ levels of theory. References: Katritzky, A. R.; Singh, H.; Tewari, S. P. Chem. Commun. 2005, 7, 868-870. Crowhurst, L.; Mawdsey, P. R.; et al. Phys. Chem. Chem. Phys. 2003, 5, 2790-2794.

Gas-phase acidities of nitrated azole species from the extended kinetic method

249th National Meeting (2015)

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