ENTROPY-CONTROLLED REACTIVITY OF SINGLET OXYGEN(1-DELTA-G) TOWARD FURANS AND INDOLES IN TOLUENE - VARIABLE-TEMPERATURE STUDY BY PULSE-RADIOLYSIS

The pulse radiolysis technique has been used to produce singlet oxygen O2 * (1Δg), the subsequent reactivity of which has been followed by the time-resolved bleaching of diphenylisobenzofuran (DPBF). The rate constants for reaction of O2 * (1Δg) with a series of furans, cyclopentadiene, and some indoles have been determined. These constants are temperature independent, and it is concluded that the reactions involve either (a) a concerted step leading directly to endoperoxide ordioxetane which is purely entropy controlled or (b) production in a rate-determining entropy-controlled step of an intermediate which rapidly rearranges to products. © 1979, American Chemical Society. All rights reserved.