The Photoreduction of Acridine in Deaerated and Aerated Alcohol Solutions. II.

Abstract

Abstract The photoreduction of acridine in methanol and isopropanol has been studied and the following results obtained : 1) The quantum yield for the photoreduction in the dagassed solution is, for methanol, 0.13 and, for isopropanol, 0.09. The photoreduction can take place even in an air-saturated solution with quantum yields of 0.032 for methanol) and of 0.032 (for isopropanol). 2) In case of a degassed solution, the product is acridan for both isopropanol and methanol, while in an aerated solution the product is acridan in the case of methanol and mainly diacridan in the case of isopropanol. 3) When the concentration of oxygen is of the order of that of acridine, the reaction proceeds at first at a rate equal to that of an air-saturated solution and then, from the point at which the oxygen is exhausted, the rate increases up to the value of a degassed solution. 4) The ratio of the quantities of oxygen and of acridine consumed before the break is, for methanol, about 3 and, for isopropanol, 5.3. 5) By the sensitizing action of acridine, acridan is oxidized to acridine in the presence of aldehyde (or acetone) and a small quantity of oxygen. 6) On the basis of the scheme proposed in the preceding paper and from the reaction product, some tentative discussion of the scheme has been undertaken. It seems plausible that, in the case of ethanol and methanol, AH· + RH· → AH2 + R occurs, while in the case of isopropanol, AH· + AH· → AH2 + A and RH· + RH· → take place (for a degassed solution).