Mechanistic investigation of the atmospheric oxidation of bis(2-chloroethyl) ether (ClCH2CH2OCH2CH2Cl) by OH and NO3 radicals and Cl atoms: a DFT approach.

Abstract

The oxidation of bis(2-chloroethyl) ether (ClCH2CH2OCH2CH2Cl) in the atmosphere, as initiated by various oxidants (OH and NO3 radicals and Cl atoms), was examined using the functional M06-2X in conjunction with the basis set 6-31 + G(d,p). We explored the oxidation pathways and reaction energies (enthalpies and Gibb's free energies) for the abstraction of H from the -CH2Cl and -OCH2 sites of ClCH2CH2OCH2CH2Cl by oxidants. The energy profile shows that H abstraction from the -OCH2 site of the title molecule by each atmospheric oxidant is more likely than H abstraction from the other site. The resulting radical ClCH2C•HOCH2CH2Cl was found to more stable than any other product, as shown by their reaction energies. The rate constants of the oxidation reactions were also calculated using canonical transition state theory in the temperature range 298-400K. The calculated total rate constant at 298K is consistent with the reported experimental rate constant. The branching ratio percentages and global atmospheric lifetime of the title molecule are also reported herein.