Conductivity, Viscosity, Spectroscopic Properties of Organic Sulfonic Acid solutions in Ionic Liquids

Sulfonic acids in ionic liquids (ILs) are used as catalysts, electrolytes, and solutions for metal extraction. The sulfonic acid ionization states and the solution acid/base properties are critical for these applications. Methane sulfonic acid (MSA) and camphor sulfonic acid (CSA) are dissolved in several IL solutions with and without bis(trifluoromethanesulfonyl)imine (HTFSI). The solutions demonstrated higher conductivities and lower viscosities. Through calorimetry and temperature-dependent conductivity analysis, we found that adding MSA to the IL solution may change both the ion migration activation energy and the number of “free” charge carriers. However, no significant acid ionization or proton transfer was observed in the IL solutions. Raman and IR spectroscopy with computational simulations suggest that the HTFSI forms dimers in the solutions with an N-H-N “bridged” structure, while MSA does not perturb this hydrogen ion solvation structure in the IL solutions. CSA has a lower solubility in the ILs and reduced the IL solution conductivity. However, in IL solutions containing 0.4 M or higher concentration of HTFSI, CSA addition increased the conductivity at low CSA concentrations and reduced it at high concentrations, which may indicate a synergistic effect.

Prediction of Thermodynamic and Structural Properties of Sulfamerazine and Sulfamethazine in Water Using DFT and ab Initio Methods

The acid-ionization constant (pK_a) is an important physico-chemical property of molecules. In this research work, the ab initio and density functional theory (DFT) methods, in combination with the polarized continuum model (PCM), were used to calculate the acid-ionization constant of sulfamethazine (SMZ) and sulfamerazine (SMR) solved in water. For these molecules, the calculated pK_a value is in relatively good agreement with the experimental one. Also, in these calculations some structural properties such as dihedral angle between the indicated atoms: D, bond lengths between the indicated atoms: d, Bohr radius: a˳, intermolecular hydrogen bond: IHB, and total atomic charge: au have been determined. These data can be used in nano drug modeling of sulfamethazine and sulfamerazine.

First acid ionization constant of the drinking water relevant chemical cyanuric acid from 5 to 35 °C

The first acid ionization constant (K6) for cyanuric acid was determined from 5 to 35 °C where or and ΔH° = 33.4 ± 1.7 kJ mol−1.