Effect of High Pressure on Polarographic Parameters of 1-(2-Pyridylazo)-2-naphthol and 4-(2-Pyridylazo)-resorcinol in Methanol-Water Mixed Solution

The dependence of polarographic parameters on pressure and temperature for the reduction of 2.0 M 1-(2-pyridylazo)-2-naphthol (PAN) and 5.0 M 4-(2-pyridylazo)-resorcinol(PAR) in buffered methanol-water mixed solution at the dropping mercury electrode, has been discussed. In this experiment the temperature is varied from 25 to 35 and the pressure is ranging from 1 atmosphere to 1,800 atmospheres. The reduction half-wave potentials are shifted to the more positive potentials with increase in pressure. The diffusion currents of two depolarizers become considerably larger with increase in pressure from 1 atmosphere to about 1,000 atmospheres but are getting smaller above 1,000 atmospheres. The slopes of log plot become much larger with increase in pressure, which indicates the more irreversible reduction. The reduction currents of two depolarizers are found to be diffusion controlled over all pressure ranges. The linear relationships between diffusion current and the concentration of two depolarizers are good agreement over all pressure ranges (1 atm∼1,800atm.).