Eliminations from (E)-2,4-Dinitrobenzaldehyde O-Aryloximes Promoted by R<sub>3</sub>N/R<sub>3</sub>NH<sup>+</sup>in 70 mol% MeCN(aq). Effects of Leaving Group and Base-Solvent on the Nitrile-Forming Transition-State
作者:Bong Rae Cho、Sang Yong Pyun
DOI:10.5012/bkcs.2013.34.4.1030
日期:2013.4.20
between the base catalyst and the leaving group. The negligible pxy interaction coefficient is consistent with the (E1cb)irr mechanism. Change of the base-solvent system from R3N/MeCN to R3N/R3NH + -70 mol % MeCN(aq) changed the reaction mechanism from E2 to (E1cb)irr. Noteworthy was the relative insensitivity of the transition state structure to the reaction mechanism change.
Elimination reactions of (E)-O-p-nitrophenyl-2,4-dinitrobenzaldoxime promoted by triethylamine in MeCNH2O
作者:Bong Rae Cho、Choon-Ock Maing Yoon、Kyung Sun Song
DOI:10.1016/0040-4039(95)00510-j
日期:1995.5
Eliminationreactions of (E)-O-p-nitrophenyl-2,4-dinitrobenzaldoxime promoted by triethylamine in MeCNH2O proceeded by the E2 mechanism. The rate decreased as the mole % of MeCN increased up to 70 % and then increased upon further increase in the MeCN concentration. The results have been interpreted with the solvent effect.
Elimination Reactions of (<i>E</i>)-2,4-Dinitrobenzaldehyde <i>O</i>-Aryloximes Promoted by RO<sup>-</sup>/ROH Buffers in EtOH
作者:Bong Rae Cho、Nam Soon Cho、Kyung Sun Song、Ki Nam Son、Yong Kwan Kim
DOI:10.1021/jo972192v
日期:1998.5.1
Elimination reactions of (E)-2,4-dinitrobenzaldehyde O-aryloximes 1-3 promoted by EtO-, PhC(CH3)=NO-/PhC(CH3)=NOH, and CF3CH2O-/CF3CH2OH buffers in ethanol have been studied kinetically. The reactions produced 2,4-dinitrobenzonitrile and aryloxides as the only products. The observed second-order kinetics, Bronsted beta = 0.55-0.75, \beta(1g)\ = 0.39-0.48 are consistent with the E2 mechanism. The Bronsted beta decreased as the leaving group was made more nucleofugic and the \beta(1g)\ increased with a weaker base. The result can be described by a positive interaction coefficient, p(xy) = partial derivative beta/partial derivative pK(1g) = partial derivative beta(1g)/partial derivative PKBH > 0, which provides additional support for the E2 mechanism.
Eliminations from (E)-2,4-Dinitrobenzaldehyde O-Aryloximes Promoted by R<sub>3</sub>N in MeCN. Effects of β-Aryl Group and Base-Solvent on the Nitrile-Forming Transition-State
作者:Bong-Rae Cho、Eun-Mi Ryu、Sang-Yong Pyun
DOI:10.5012/bkcs.2012.33.9.2976
日期:2012.9.20
the product by astronger base in the reaction coordinate diagram. On theother hand, when the leaving group was changed from 2,4-dinitrophenoxide to picrate, the ρ value decreased but the βvalue increased. The results are in conflict with the predic-tion of the reaction coordinate diagram because both ρ and βvalues should be decreased with a better leaving group. Theunusual changes in the transition-state