Temperature effects on rates of dehalogenation of aromatic anion radicals

Electrochemically reduced titanocene dichloride as a catalyst of reductive dehalogenation of organic halides

“…However, the abstraction of the halogen from aryl halides is much slower than from the corresponding benzyl halide. This difference is correlated with the calculated rate constants for dissociation of C X -bond in anion radicals of nitroaryl [26] and nitrobenzyl [27] type, yielding an organic radical and halide anion: lg k = 3.9 (X = Cl) and 5.7 (X = Br) for p-NO 2 C 6 H 4 CH 2 X while lg k = −6.0 (X = Cl) and −2.9 (X = Br) for NO 2 C 6 H 4 X.…”

Theoretical study on haloaromatic radical anions and their intramolecular electron transfer reactions

“…Energy differences for halobenzenes and 2-halopyridines (Table 1) indicate that the fragmentation reaction rate follows the order: C1 < Br < I as is known from experimental determinations for other haloaromatic compounds. 34 For halobenzenes, the fragmentation rate has been shown to be d i f f u ~i o n a l , ~" ~~ while AM 1 seems to overestimate their activation barriers.…”

Rates of reductive elimination of substituted nitrophenols from the (indol-3-yl)methyl position of indolequinones

“…4 is a test of a linear relationship between log k 3 and pK a and a comparison with elimination rates of the leaving groups shown in the radical anions of 4-nitrobenzyl halides and toluene-p-sulfonates (see Discussion). 16,17 Our previous studies have shown that incorporation of a methyl or heterocyclic substituent at the (indol-3-yl)methyl position significantly enhanced the rate of reductive elimination from the Q ؒϪ radical. 13 The rate of reductive fragmentation of 6 is k 3 = 41 s Ϫ1 and substitution with methyl at the R 3 Ј position to give 7 increases the rate 10-fold to k 3 = 520 s Ϫ1 .…”