Comparison of acidity function and linear free energy basicity constants of amides, phenylureas, and nitroanilines

Abstract

The Bunnett-Olsen linear free relationship¹ has been used to determine the thermodynamic basicity constants, K_BH+, of 22 amides, 8 phenylureas, and 9 nitroanilines. These values have been compared with the basicity constant determined by plotting log I against the appropriate acidity function. For amides and phenylureas the two values of pK_BH+ differ by <0.3 logarithm units, whereas for nitroanilines the difference increases with decreasing basicity and may be as large as 2.1 logarithm units.