PULSE-RADIOLYSIS OF ALKANES - A TIME-RESOLVED EPR STUDY .2. PHENOLIC ADDITIVES

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 (HArOH)-Ar-.. 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 (HArOH)-Ar-. radicals is responsible for the early-time A/E polarization in these species.