1B-O1-1445 PDF
Calculation of average-dipole-orientation rate constants for proton transfer reactions between H3O+ and atmospheric trace gases using molecular mass and elemental composition
The average-dipole-orientation (ADO) theory describes how exothermic proton transfer reaction (PTR) rate constants between H3O+ and hydrocarbons are accurately obtained using polarizabilty and permanent dipole moment of those compounds. Here we found that polarizability and dipole moment of various different volatile organic compounds (VOCs) can be accurately predicted only using molecular mass, elemental composition, and functional groups of VOCs. The polarizabilities of a class of VOCs possessing specific species and number of electronegative atoms were linearly correlated with their molecular mass, whereas dipole moments in a series of VOCs, in which VOCs consist of a definite functional group and arbitrary residual hydrocarbon parts, were approximated as a constant value. These made it possible to comprehensively calculate PTR rate constants of atmospherically important VOCs according to the ADO theory. The accuracy of the resulting ADO rate constants with respect to those that were previously measured was within 10 % for almost all VOCs. This work would apply to determine of the concentration of various VOCs in the atmosphere by PTR-ToF-MS without the necessity of calibration.