K. Ohara et al., CW AND FT TIME-RESOLVED EPR INVESTIGATION OF THE QUENCHING REACTION OF THE 2-HYDROXYPROPAN-2-YL RADICAL, Journal of physical chemistry, 100(8), 1996, pp. 3070-3074
The secondary quenching reactions of the 2-hydroxypropan-2-yl radical
produced by photolysis of pyrazine, quinoxaline, and p-benzoquinone in
2-propanol were investigated with time-resolved EPR. The quenching ra
te constants are 6.6 x 10(6), 1.2 x 10(8), and similar to 10(8) M(-1)
s(-1) for pyrazine, quinoxaline, and p-benzoquinone, respectively. The
time profiles of the transient EPR signals of pyrazinyl and 2-hydroxy
propan-2-yl radicals were measured by FT-EPR and analyzed in detail in
terms of a reaction scheme involving the primary hydrogen abstraction
reaction and the subsequent quenching reaction. It is found that half
of the signal intensity of the pyrazinyl radical arises from polariza
tion transfer accompanying 2-hydroxypropan-2-yl quenching by pyrazine.