Photochemistry of chlorinated diphenyl ethers

The photoreactions of a series of chlorinated diphenyl ethers at wavelengths around 300 nm were investigated as to their photodecomposition rates and products formed. No significant differences in reaction rates were found between chlorodiphenyl ethers with up to four chlorine atoms per molecule which reacted slower than the pentachlorodiphenyl ethers investigated. The major products resulted from photodechlorination reactions but compounds with chlorine substituents in the 2 or 6 positions also gave rise to chlorinated dibenzofurans in about 10% yields. The yields of dibenzofurans were increased in most cases when photolysis was carried out in the presence of acetone. This reaction may also occur under natural conditions in the environment by influence from natural products which have photochemical characteristics similar to that of acetone