Equilibrium acidities of some carbon acids in acetonitrile

The pK a values for C-acids (4-nitrophenylnitroalkanes, 4-nitrophenyl-(4-X-phenyl)cyanomethanes, 2,4,6-trinitrotoluene, and 9-cyanofluorene) in acetonitrile have been measured. These values were determined spectrophotometrically in buffer solutions consisting of a strong amine base and its picrate or perchlorate using known potentiometric pKa's of amines, and they range from 19 for bis(4-nitrophenyl)cyanomethane to 25.1 for ethyl bis(4-nitrophenyl)acetate. Keywords: C-acids, pKa values, equilibrium, reactivity, proton transfer reaction.