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N,N-Dimethylaniline의 아조커플링 반응에 關한 硏究
金容仁,明孝信 弘益大學校 1982 弘大論叢 Vol.14 No.2
The coupling reaction of N, N-dimethylaniline with several monosubstituted benzenediazonium salts has been studied kinetically in aqueous buffered solution. The activation evergies measured in the coupling reaction of N, N-dimethylaniliine with diazotized p-nitroaniline, m-nitroaniline, sulfanilic acid, m-anisidine,p-anisidine, p-bromoaniline, p-chloroaniline, m-toluidine, p-toluidine are 8.46, 8.05, 9.20, 12.32, 15.91, 10.86, 11.54, 13.80, 14.35, 15.47Kcal/mole, respectively. The coupling reactionis more favorable in the presence of an electron-withdrawing group in active components than in the presence of electron-donating group. It has been observed that the coupling reaction with diazotized p-nitroaniline proceeds 1000 times more rapidly than that with the benzenediazonium salt, which is coupled 40 times faster than diazotized p-anisidine. In our experiments, the formation of triazene, the diazoamino compound has not been observed, and the experimental result that the ionic strength of the medium didn't give any influence on the coupling reaction rate leads to the confirmation of the neutral free amine being one of the reasonable reactive species in the coupling reaction. A linear free energy relationship has been essentially observed except for three para substituted active components, for which the extended Hammett plot treated by Yukawa-Tsuno permits a good log k/k??=ρ(σ+ rㆍ????) linear relationship when considering the mesomeric effect. The calculated reaction constant of these azocoupling reaction is ρ=3.92, and the reaction constant of resonance contribution is calculated as r=0.32 at 20 ℃.