Atmospheric chemistry of 1,4-dioxane. Laboratory studies

A pulse radiolysis technique was used to measure the UV absorption spectra of c-C4H7O2 and (c-C4H7O2)O2 radicals over the range 220-320 nm, σ(c-C4H7O2)250 nm = (5.9 ± 0.6) × 10-18 and σ[(c-C4H7O2)O2]240 nm = (4.8 × 0.8) × 10-18 cm2 molecule-1. The observed self-reaction rate constants for the c-C4H7O2 and (c-C4H7O2)O2 radicals, defined as -d[c-C4H7O2]/dt = 2k4[c-C4H7O2]2 and -d[(c-C4H7O2)O2]/dt = 2k5 obs[(c-C4H7O2)O2]2 were k4 = (3.3 ± 0.4) × 10-11 and k5 obs = (7.3 ± 1.2) × 10-12 cm3 molecule-1 s-1.

The rate constants for reactions of (c-C4H7O2)O2 radicals with NO and NO2 were k6 (1.2 ± 0.3) × 10-11 and k7 = (1.3 ± 0.3) × 10-11 cm3 molecule-1 s-1, respectively. The rate constants for the reaction of F atoms with 1,4-dioxane and the reaction of c-C4H7O2 radicals with O2, were k3 = (2.4 ± 0.7) × 10-10 and k2 = (8.8 ± 0.9) × 10-12 cm3 molecule-1 s-1, respectively.

A relative rate technique was used to measure the rate constant for the reaction of Cl atoms with 1,4-dioxane, k17 = (2.0 ± 0.3) × 10-10 cm3 molecule-1 s-1. A long-pathlength FTIR spectrometer coupled to a smog chamber system was used to show that the sole atmospheric fate of the alkoxy radical (c-C4H7O2)O is decomposition via C-C bond scission leading to the formation of H(O)COCH2CH2OC(O)H (ethylene glycol diformate).