Investigation of the reactivity of 4-pyrimidinecarboxylic, 6-hydroxy-4-pyrimidinecarboxylic and 5-hydroxyorotic acids with diazodiphenylmethane in various alcohols: Part III

Rate constants for the reaction of diazodiphenylmethane (DDM) with 4-pyrimidinecarboxylic, 6-hydroxy-4-pyrimidinecarboxylic and 5-hydroxyorotic acids were determined in twelve protic solvents at 30 °C using the well known UV-spectrophotometric method. The second order rate contants for the examined acids were correlated using the appropriate solvent parameters by the equation log k = log k0 + af( )+ b * + cnH were f() is the Kirkwood function of relative permittivity ((-l)/(2 +1) ), * is the Taft polar constant for the alkyl group R in the alcohol ROH, and nyH is the mumber of hydrogen atoms in the -position in the alco- hol. The results obtained for the investigated acids were compared with the corre- sponding results for benzoic, 2- and 3-hydroxybenzoic acids and the influence of the structure of the investigated acids on the reactivity in hydroxylic solvents is dis- cussed. It was also possible to evaluate and distinguish the specific and non-specific solvent effects and their influence on the reaction rate.