Photochemical degradation of 1-and 2-methylphenanthrenes in acetonitrile and on some solids

In order to obtain basic information about photochemical degradability and degradation products for 1- and 2-methylphenanthrenes (MPs), photodegradati on of these compounds in an organic solvent (acetonitrile) and on some soli ds (soil, silica gel [SiO2], and titanium dioxide [TiO2]) were carried out in a laboratory using solar simulators. The results showed that the degradation rate (%) increases in the order of TiO2 > SiO2 > acetonitrile > soil. Products formed in acetonitrile included aromatic compounds with molecular ion [M+] peaks at m/z = 148, 162, 198, 2 06, 208, 210, 222, 224 and 238. In case of IMP, a compound with Mt 206, whi ch was identified as 1-phenanthrene-carbaldehyde, was predominantly formed. However, 2MP showed no predominance for M+ 206 and also yielded M+ 210 and M+ 224 as major products. Degradation on soil and SiO2 gave similar produc ts to those detected in acetonitrile, while that on TiO2 gave different pro ducts from the formers. Based on the results of product analysis, three deg radation pathways which may occur in acetonitrile are proposed.