Kinetics of the reaction of 5-substituted orotic acids with diazodiphenylmethane

Rate konstants for the reaction of eight 5-substituted orotic acids with diazodiphenylmethane (DDM) in dimethylformamide (DMF) were determined at 30 oC by the known spectrophotometric method. The determined rate constants were correlated with the equations: log k2 = as1 + bsR + h log k2 = as1 + bsR + yn + h to detect the presence and investigate the influence of both electrical and steric substituent effects. The obtained results show that the electrical effect (the localized field and delocalized resonance) is predominant and that the steric effect, althought present, is releatively small in this reaction.