The α-Effect in Nucleophilic Substitution Reactions of Y-Substituted-Phenyl X-Substituted-Cinnamates with Butane-2,3-dione Monoximate
作者:Min-Young Kim、Yu-Jin Son、Ik-Hwan Um
DOI:10.5012/bkcs.2013.34.10.2877
日期:2013.10.20
Second-order rate constants ($k_Ox^-}$) have been measured spectrophotometrically for nucleophilic substitution reactions of 4-nitrophenyl X-substituted-cinnamates (7a-7e) and Y-substituted-phenyl cinnamates (8a-8e) with butane-2,3-dione monoximate ($Ox^-$) in 80 mol % $H_2O$/20 mol % DMSO at $25.0\pm}0.1^\circ}C$. The Hammett plot for the reactions of 7a-7e consists of two intersecting straight lines while the Yukawa-Tsuno plot exhibits an excellent linearity with $\rho}_X$=0.85 and r=0.58, indicating that the nonlinear Hammett plot is not due to a change in the rate-determining step but is caused by resonance stabilization of the ground state (GS) of the substrate possessing an electron-donating group (EDG). The Br$\o}$nsted-type plot for the reactions of Y-substituted-phenyl cinnamates (8a-8e) is linear with $\beta}_lg}$ = -0.64, which is typical of reactions reported previously to proceed through a concerted mechanism. The $\alpha}$-nucleophile ($Ox^-$) is more reactive than the reference normal-nucleophile ($4-ClPhO^-$). The magnitude of the $\alpha}$-effect (i.e., the $k_Ox^-}/k_4-ClPhO^-}$ ratio) is independent of the electronic nature of the substituent X in the nonleaving group but increases linearly as the substituent Y in the leaving group becomes a weaker electron-withdrawing group (EWG). It has been concluded that the difference in solvation energy between $Ox^-$ and $4-ClPhO^-$ (i.e., GS effect) is not solely responsible for the $\alpha}$-effect but stabilization of transition state (TS) through a cyclic TS structure contributes also to the Y-dependent $\alpha}$-effect trend (i.e., TS effect).
Kinetic study on aminolysis of aryl X-substituted-cinnamates in acetonitrile: differential medium effect determines reactivity and reaction mechanism
作者:Ik-Hwan Um、Ae-Ri Bae、Julian M. Dust
DOI:10.1139/cjc-2018-0310
日期:2019.1
A kineticstudy on nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted-cinnamates (1a–1f) and Y-substituted-phenyl cinnamates (2a–2g) with a series of alicyclic secondary amines in MeCN at 25.0 ± 0.1 °C is reported. The Bronsted-type plots for the reactions of 1a–1f are linear with βnuc = 0.47∼0.50, indicating that the bond formation between the amine nucleophile and the electrophilic
The present invention provides a novel diamine and a novel acid anhydride which are applicable for a polyimide and includes a cinnamoyl group or a derived cinnamoyl group. The novel diamines and acid anhydrides have photo-reactivity and heat-reactivity inherent to the cinnamoyl group.
Structure-Reactivity Correlations in Nucleophilic Displacement Reactions of Y-Substituted-Phenyl X-Substituted-Cinnamates with Z-Substituted-Phenoxides
作者:Yu-Jin Son、Eun-Hee Kim、Ji-Sun Kang、Ik-Hwan Um
DOI:10.5012/bkcs.2013.34.8.2455
日期:2013.8.20
linear correlation with ρX = 0.89 and r = 0.58. The Bronsted-type plot for the reactions of 4-nitrophenyl cinnamate (4c) with Z-substituted-phenoxides is linear with βnuc = 0.76. The Bronsted-type plot for the reactions of Y-substituted-phenyl cinnamates (5a-5d) with 4-chlorophenoxides (4ClPhO – ) is also linear with βlg = –0.72. The Hammett plot correlated with σ – constants for the reactions of 5a5d
The present invention provides a novel polyimide composition which includes a cinnamoyl group or a derived cinnamoyl group and has photo-reactivity and heat-reactivity inherent to the cinnamoyl group. Further, a novel diamine and an acid dianhydride according to the present invention are materials mainly used for preparing a novel polyimide composition having the cinnamoyl group or the derived cinnamoyl group in a main chain or a side chain.