Photochemical degradation of brominated dibenzo-p-dioxins and -furans in organic solvents

The photolytic behavior of halogenated dibenzo-p-dioxins and -furans in the organic solvents methanol and n-hexane was investigated and the corresponding quantum-yields and first order decay rates are reported. The photolysis constants in n-hexane increase with increasing number of bromine atoms in the dibenzo-p-dioxin or dibenzofuran skeleton, e.g. from 4.5×10^-4 s^-1 for the monobrominated to 7.7×10^-3 s^-1 for the octabrominated dioxin, and from 4.0×10^-3 s^-1 for the dibrominated to 8.3×10^-2 s^-1 for the heptabrominated furan. Photolysis in methanol is nearly six times slower than in n-hexane. The bromine compounds react an order of magnitude faster than the chlorine analogues. The results were used to extrapolate the photochemical fate to lipohilic environmental surfaces.