4450-67-3Relevant articles and documents
NUCLEOPHILIC SUBSTITUTION REACTION OF BENZYL BENZENESULFONATES WITH ANILINES IN MeOH-MeCN MIXTURES-I. EFFECTS OF SUBSTITUENT AND SOLVENT ON THE TRANSITION-STATE STRUCTURE.
Lee, Ikchoon,Lee, Won Heuy,Sohn, Se Chul,Kim, Choong Shik
, p. 2635 - 2642 (1985)
Kinetic studies on nucleophilic substitution reaction of benzyl tosylates with anilines are reported.The reaction was found to proceed via a dissociative SN2 mechanism with less than 50 percent bond formation and extensive bond breaking at the transition state.It was found that positive charge development at the benzylic carbon is substantial and para-substituent effect on the substrate is predominantly of resonance type.Bond formation is shown to be favored by a better nucleophile, by an electron withdrawing group on the substrate and by the more polar(higher MeCN content) solvent.The substrate, nucleophile and solvent were found to follow the RSP.
Reversed electron apportionment in mesolytic cleavage: The reduction of benzyl halides by SmI2
Yitzhaki, Offir,Hoz, Shmaryahu
, p. 9242 - 9248 (2015/06/16)
The paradigm that the cleavage of the radical anion of benzyl halides occurs in such a way that the negative charge ends up on the departing halide leaving behind a benzyl radical is well rooted in chemistry. By studying the kinetics of the reaction of substituted benzylbromides and chlorides with SmI2 in THF it was found that substrates para-substituted with electron-withdrawing groups (CN and CO2Me), which are capable of forming hydrogen bonds with a proton donor and coordinating to samarium cation, react in a reversed electron apportionment mode. Namely, the halide departs as a radical. This conclusion is based on the found convex Hammett plots, element effects, proton donor effects, and the effect of tosylate (OTs) as a leaving group. The latter does not tend to tolerate radical character on the oxygen atom. In the presence of a proton donor, the tolyl derivatives were the sole product, whereas in its absence, the coupling dimer was obtained by a SN2 reaction of the benzyl anion on the neutral substrate. The data also suggest that for the para-CN and CO2Me derivatives in the presence of a proton donor, the first electron transfer is coupled with the proton transfer. Reverse breakup: In the mesolytic cleavage of the radical anions of benzyl halides that are para-substituted by CN or CO2Me groups, the halogen departs, counterintuitively, as a radical and the benzyl system carries the negative charge (see figure).
