16887-61-9Relevant articles and documents
Elimination reactions of (Z)-thiophene- and (Z)-furan-2-carbaldehyde O- benzoyloximes. Effect of β-aryl group upon the nitrile-forming anti transition state
Cho, Bong Rae,Cho, Nam Soon,Song, Sang Hun,Lee, Sang Kook
, p. 8304 - 8309 (2007/10/03)
Elimination reactions of (Z)-thiophene- and (Z)-furan-2-carbaldehyde O- benzoyloximes 1 and 2 with DBU in MeCN have been investigated kinetically. The reactions are second order and exhibit substantial values of Hammett ρ and k(H)/k(D) values, and an E2 m
Kinetics of deprotonation of arylnitromethanes by benzoate ions in acetonitrile solution. Effect of equilibrium and nonequilibrium transition-state solvation on intrinsic rate constants of proton transfers
Gandler, Joseph R.,Bernasconi, Claude F.
, p. 631 - 637 (2007/10/02)
Second-order rate constants for benzoate ion promoted deprotonation reactions of (3-nitropbenyl)nitromethane, (4-nitrophenyl)nitromethane, and (3,5-dinitrophenyl)nitromethane have been determined in acetonitrile solution at 25 °C. These data were obtained at low benzoate buffer concentrations (a= 21.7; (4-nitromethyl)nitromethane, pKa = 20.6; and (3,5-dinitrophenyl)nitromethane, pKa, = 19.8. A Br?nsted βB value of 0.56 and an αCHlue of 0.79 have been calculated for the benzoate, 3-bromobenzoate, and 4-nitrobenzoate ion promoted reactions of (3,5- dinitrophenyl)nitromethane and for the benzoate ion promoted reactions of (3- nitrophenyl)nitromethane and (3,5-dinitrophenyl)nitromethane, respectively; (4-nitrophenyl)nitromethane deviates negatively from the Bronsted plot due to the resonance effect of the 4-nitro group. The logarithms of the intrinsic rate constants for benzoate promoted deprotonations of (3-nitrophenyl)nitromethane, (4-nitro phenyl)nitromethane, and (3,5-dinitrophenyl)nitromethane are 4.81, 4.58, and 5.27, respectively, and these values are 1.43, 1.70, and 1.30 log units, respectively, higher in acetonitrile than in dimethyl sulfoxide. Transfer activity coefficients from dimethyl sulfoxide (D) to acetonitrile (A) solution, log DγA, for (3-nitropbenyl)nitroimethyl anion (0.28), (4-nitrophenyl)nitromethyl anion (0.56), (3-nitrophenyl)nitromethane (0.18), and (4-nitrophenyl)nitromethane (0.16) have been calculated, and log DγA for benzoic acid (～ 1.9) and the benzoate ion (～0.25) have been estimated. The solvent effects on the intrinsic rate constants are analyzed within the framework of the Principle of Nonperfect Synchronization (PNS) in terms of contributions by late solvation of the arylnitromethyl anion, late solvation of the benzoic acid (produced as a product of the reaction), early desolvation of the benzoate ion and the arylnitromethane, and by a classical solvent effect. The results are also compared with predictions by a theoretical model recently proposed by Kurz. For the comparison of intrinsic rate constants in water and dimethyl sulfoxide there is good agreement between the Kurz model and the experimental results as well as the PNS analysts, but there is a discrepancy between the results and the predictions of the Kurz model for the comparison of intrinsic rate constants in dimethyl sulfoxide and acetonitrile solutions.
