Theoretical studies of ethylnitrolic acid using Gaussian

Abstract

The tautomerism of all possible forms of ethylnitrolic acid was investigated theoretically in various environment including gas phase, ethanol, dimethyl sulfoxide (DMSO) and water. The calculations were carried out at DFT/B3LYP and MP2 of theory singly. It was found that, form of B eythynitrolic acid is the most stable isomer in the both gas phase and solvent. The activation energies for conversion of A to R and B to A in the gas phase and solvent using two methods DFT/B3LY and MP2 were obtained. Geometrical parameters of three isomers, A, B and R, were calculated by (DFT/B3LYP and MP2) in the gas phase and solvent. Vibrational analysis and acidity constants (PKa) of two isomers (A and R) were computed in the gas phase and water using DFT/B3LYP and MP2. After that, these quantities were evaluated with experimental values and it was determined that DFT/B3LYP is more accurate to obtain PKa.

Keywords: Tautomerism; ethylnitrolic acid; solvent effect; proton transfer reaction; acidity constant.