PULSE RADIOLYSIS OF ALKANES: A TIME-RESOLVED EPR STUDY—PART Ⅱ. PHENOLIC ADDITIVES

摘要

Time-resolved spin-echo-detected EPR was applied to observe transient radicals formed in pulse radiolysis of phenols, ArOH, in alkanes at 290 K. It is demonstrated that phenoxy radicals ArO~· are produced in dissociative capture of electrons, alkane holes and via reaction of phenols with hydrogen atoms. Another product of the latter reaction is cyclohexadienyl-type radical H~·ArOH. H atoms add exclusively to the para-position of phenols. A rapid multi-step transfer of singlet spin correlation from the geminate radical ion pairs to the pairs involving ArO~· and H~·ArOH radicals is responsible for the early-time A/E polarization in these species.