Spectrophotometric studies of proton transfer complexes between 2-amino-4-methoxy-6-methyl-pyrimidine and 2-amino-4,6-dimethyl-pyrimidine with 2,6-dichloro-4-nitrophenol in acetonitrile

2-Amino-4-methoxy-6-methyl-pyrimidine (AMMP) and 2-amino-4,6-dimethyl-pyrimidine (ADMP) react with 2,6-dichloro-4-nitrophenol (DCNP) to form yellow proton transfer (PT) complexes in acetonitrile at absorption maxima around 420 nm. These PT reactions have been applied to the simultaneous spectrophotometric determination of (AMMP) and (ADMP) in acetonitrile. Factors controlling the PT process were studied and optimized. Job's method of continuous variations was applied to identify the composition of the formed complexes. The PT complex formation constants (KPT) and the molar extinction coefficients (ε) were estimated using Benesi-Hildebrand equation. Moreover, the solid PT complexes were isolated and characterized using elemental analysis and infrared measurements.