24311-17-9Relevant academic research and scientific papers
Reaction of Azide Radicals with Aromatic Compounds. Azide as a Selective Oxidant
Alfassi, Zeev B.,Schuler, Robert H.
, p. 3359 - 3363 (2007/10/02)
In basic aqueous solution the N3. radical is found to oxidize aromatic systems such as aniline and phenoxide ions and their deivatives at rate constants of (3-5) X 109 M-1s-1.In contrast to the reactions of OH radicals, wh
Gas-Phase Nucleophilic Reactivities of Phenylnitrene (PhN-*) and Sulfur Anion Radicals (S-/.) at sp3 and Carbonyl Carbon
McDonald, Richard N.,Chowdhury, A. Kesem
, p. 198 - 207 (2007/10/02)
The reactions of PhN-/. with a series of carbonyl-containing molecules (aldehydes, ketones, and esters) were shown to proceed via an addition/fragmentation mechanism, PhN-* + R2C=O -> -)R2> -> PhN=C(O-)R + *R, producing various acyl anilide anion products.In several cases, the tetrahedral intermediate anion radicals were observed as minor ions.The intrinsic reactivity of the carbonyl-containing molecules was aldehydes > ketones > esters, where similar R groups were involved.The overall exothermicities of these reactions did not appear to play the major role in determining the relative rates (krelC=O) for these reactions.From the reaction of PhN-* with cyclobutanone, a new type of anion radical, PhN=C(O-)CH2* (m/z 133) (+ C2H4) was produced; the loss of C2H4 was considered due to the ring strain in the ketone.With cyclopentanone, cyclohexanone, and cycloheptanone, the anion radicals PhN=C(O-)(CH2)n* (n = 4-6) were the exclusive product ions.PhN-* was shown to be a poor nucleophile in SN2 displacement reactions with CH3X molecules (X = Cl, Br, O2CCF3).S-* was shown to exhibit modest SN2 nucleophilicity with CH3Cl and CH3Br.The reactions of S-* with CF3CO2R proceed via both SN2 displacement and carbonyl addition/fragmentation mechanisms: with R = CH3, the anion products were 65percent CF3CO2- and 35percent CF3COS-; from R = C2H5, the product ions were 4percent CF3CO2- and 96percent CF3COS-.These data yield the ratio kCH3/kC2H5 = 16 for SN2 displacement by S-* at these alkyl groups.The reactions of PhN-* with CO2, COS, CS2, and O2 are also reported.The reaction of PhN-* with CS2 to produce S-* as a major channel was used as the source of this atomic anion radical.In several reactions occuring at nearly the collison limit, selectivity was observed for (a) which of two reaction centers were attacked to give products and (b) which of two mechanisms would be dominant in the overall reaction.
Intrinsic Barriers in Nucleophilic Displacements. A General Model for Intrinsic Nucleophilicity toward Methyl Centers
Pellerite, Mark J.,Brauman, John I.
, p. 2672 - 2680 (2007/10/02)
The applicability of the Marcus rate-equilibrium formalism to the double-minimum potential energy surface for gas-phase SN2 reactions is proposed and used to develop a model for intrinsic nucleophilicity toward methyl centers.The key quantities in this model are the energy barriers to degenerate reactions of the form X(-*)CH3X -> XCH3(*)X(-), in which the reacting species are ion-molecule cluster intermediates.Available experimental and theoretical data corroborate several of the model's predictions.A new structure-nucleophilicity correlation is proposed, involving methyl cation affinities.The model suggests that delocalization effects do not greatly influence nucleophile reactivity.
