Trends in electron–ion dissociative recombination of benzene analogs with functional group substitutions: Negative Hammett σpara values

An in-depth study of the effects of functional group substitution on benzene’s electron–ion dissociative recombination (e-IDR) rate constant has been conducted. The e-IDR rate constants for benzene, biphenyl, toluene, ethylbenzene, anisole, phenol, and aniline have been measured using a Flowing Afterglow equipped with an electrostatic Langmuir probe (FALP). These measurements have been made over a series of temperatures from 300 to 550 K. A relationship between the Hammett σpara values for each compound and rate constant has indicated a trend in the e-IDR rate constants and possibly in their temperature dependence data. The Hammett σpara value is a method to describe the effect a functional group substituted to a benzene ring has upon the reaction rate constant.