Ion-molecular interactions in the methylsulfonic acid-methanol system according to the IR spectral data

The methylsulfonic acid (MSA)-methanol (MeOH) liquid binary system was studied over the whole concentration range by the MBTIR IR spectroscopy method at 30A degrees C. Quasi-ion pairs with the 1: 1 composition formed by a strong symmetrical H-bond were only present in solutions with an equimolar acid: base ratio. The addition of methanol caused the solvation of quasi-ion pairs by MeOH molecules, and, in the presence of the base in a substantial excess (C (MeOH) (0) : C (MSA) (0) > 2), proton disolvates (Me(H)Oa <-Ha <-O(H)Me)(+) with strong symmetrical H-bonds were formed; that is, there was Ba <-Ha <-A + B a dagger" (Ba <-Ha <-B)(+) + A(-) equilibrium, where B is the base molecule and HA is the acid. In the presence of excess acid, methanol was protonated, and negatively charged proton disolvates were formed, Ba <-Ha <-A + HA a dagger" BH+ + (AHA)(-). This equilibrium was fully shifted to the right.