Gas-phase Acidities of Carbon Acids

Abstract

Very strong acids are of great interest in a wide field of chemistry because of the low nucleophilicity of their conjugate anions. The relationship between molecular structure and gas-phase acidity is a useful guideline for a design of new superacids. However, recent computational studies suggested that the available GA values below 300 kcal mol-1 may be significantly in error. Therefore, in this study gas-phase acidities of strong acids including polyfluoronated alkanes have been determined by measurement of proton-transfer equilibrium using an FT-ICR spectrometer. A new scale of GA has been built up to 278 kcal mol-1, strongest acidity. In addition, the substituent effect on the acidity of -trifluoromethylsufonyl toluene have been analyzed.