Abstract
γ-Ray irradiation of a binary solution consisting of pyridine and methanol caused almost no reaction of pyridine. However, the addition of a catalytic amount of nickel nitrate to this binary solution induced the α-methylation of pyridine in good yield upon γ-ray irradiation at room temperature either in air or in vacuo. This α-methylation gave α-picoline as a major product. The yield of α-picoline increased with increase in the irradiation time at the initial stage of the reaction, reached a maximum (27.8%) at an irradiation duration of between 8 and 10h, and then decreased progressively at greater irradiation times. In addition, the yield of α-picoline at a given irradiation time showed a tendency to increase with increasing amount of the nickel nitrate catalyst or with increasing fraction of methanol in the starting solution. γ-Ray irradiation in the presence of nickel nitrate was also found to induce the catalytic α-methylation of γ-picoline with methanol at room temperature either in air or in vacuo, giving 2, 4-lutidine as a major product in a maximum yield of 8.3%. Further, the demethylation reaction of α-picoline to pyridine and that of 2, 4-lutidine to γ-picoline were also promoted greatly upon γ-ray irradiation at room temperature in air in the presence of both methanol and nickel nitrate.
