Sense of cleavage of substituted benzenes on reaction with solvated electrons, as determined by a product criterion

Reversed Electron Apportionment in Mesolytic Cleavage: The Reduction of Benzyl Halides by SmI2

“…To be more specific, the question is, why does our system involve the inverse cleavage mode whereas the other systems do not? In his work on the SRN1 mechanism, Rossi and Bunnett suggested that in a mesolytic bond cleavage, the negative charge will reside with the group that is most capable of stabilizing it 24. Yet, the benzylic systems are identical in all of the three scenarios and only in the present case, the cleavage direction is reversed.…”

“…25 Although it is unlikely that the electron‐withdrawing power of the p ‐CN and p ‐CO 2 Me substituents alone is sufficient to overcome the electronegativity of Cl and Br, their pairing with the triply charged samarium cation, apparently results in more efficient negative charge stabilization on the benzylic fragment than by its localization on the nucleofuge. Hence, according to the Bunnett paradigm,24 the mode of cleavage will be reversed. This cannot happen with the sterically hindered tetrabutylammonium cation, neither can it happen with the p ‐CF 3 substituent nor with meta substituents in which the molecular π orbital is orthogonal to the one relevant to the benzylic position.…”

Formation and decomposition of radical anions. A theoretical study

“…However, there is a difference between these two radical anions. Toluene radical anion does not decompose into reactants, but fluorobenzene radical does (5). From Figs.…”

“…Up to now, radical anions have aromatic systems are attached to a nucleofugal been studied from a theoretical ~o i n t of view by group, they decompose to yield an aromatic radical means of Hiickel-like methods combined with and an anion corresponding to the nucleofugal PMO analysis (10). Then, as a natural following group (5). The occurrence of such a reaction (6) as we deem a wmewhat well as the decomposition rate depend to a great more elaborate method which allows us to obtain a extent on the nature of the aromatic substrate, the point-by-point information about the reaction copresence of another substituent, and the position of ordinate, for elucidating the reasons responsible the leaving group with respect to the substituents for the behavior of radical anions with respect to (2,7).…”

Diphenyliodonium Chloride

“…The following reactions of carbanions using t-butyl alcohol as solvent are representative (eqs [3][4][5][6][7][8][9][10][11][12]. Among the better substrates are 1,3-dicarbonyl compounds (eqs 3,4,8, and 9), 2,3,5 α-cyano ketones (eq 6), 4 aromatic ketones (eqs 5 and 7), 4 acetone enolates (eq 10), 6 and nitronate ions (eqs 11 and 12). 7,8 Representative examples include alkoxides, 9 phenoxides, 10 carboxylates, 9 sulfonates, 9 N-oxides, 11 oximes, 12,16 hydroxylamines, 14,15 and nitroso compounds.…”