Mass spectrometric and computational studies on the reaction of aromatic peroxyl radicals with phenylacetylene using the distonic radical ion approach

Abstract

Product and mechanistic studies were performed for the reaction of aromatic distonic peroxyl radical cations 4-PyrOO•+ and 3-PyrOO •+ with phenylacetylene (7) in the gas phase using mass spectrometric and computational techniques. PyrOO•+ was generated through reaction of the respective distonic aryl radical cation Pyr•+ with O2 in the ion source of the mass spectrometer. For the reaction involving the more electrophilic 4-PyrOO •+, a rate coefficient of k1 = (2.2 ± 0.6) × 10-10 cm3 molecule-1 s-1 was determined at 298 K, while a value of k2 = (8.2 ± 2.1) × 10-11 cm3 molecule-1 s-1 was obtained for the reaction involving the less electrophilic 3-PyrOO •+. This highlights the role of polar ef..