Benzyl Benzenesulfonate 와 置換피리딘類의 反應에 關한 反應速度論的 硏究 (第5報).

Kinetics of the Reaction of Substituted Pyridines with Benzyl Benzenesulfonate (Ⅴ)

  • 이우붕 (慶北大學校 師範大學 化學科) ;
  • 여수동 (慶北大學校 師範大學 化學科) ;
  • 홍순영 (漢陽大學校 文理科大學 化學科)
  • Woo Bung Lee (Department of Chemistry, Techer's College, Kyungpook National University) ;
  • Soo Dong Yoh (Department of Chemistry, Techer's College, Kyungpook National University) ;
  • Soon Yung Hong (Department of Chemistry, Hanyang University)
  • 발행 : 1977.02.28

초록

Benzyl benzenesulfonate와 3- 또는 4-치환피리딘의 反應速度를 아세톤 용매중, $35^{\circ}C$에서 전기 전도도법으로 측정하였다. Benzyl benzenesulfonate와 피리딘의 $S_N2$반응에서 Hammett 치환기 상수와 log k를 圖示하면 반응속도는 치환기의 電子를 주는 능력이 클 수록 增加하였고 4-$NH_2$ 피리딘은 Hammett의 ${\sigma}$값보다 ${\sigma}^+$로 잘 相關지어졌다. 이 結果는 $NH_2$${\sigma}$와 피리딘 고리안의 N원자와 共鳴의 寄與가 큼을 나타낸다. Bronsted 圖示에서 4-$NH_2$와 電子를 당기는 기는 直線에서 反應이 큰쪽으로 벗어 났으며 이는 置換基에 대한 溶媒效果에 基因된다고 생각된다. 여기에 符合되는 반응메카니즘은 熱力學的 파라미터도 구하였다.

The rate constant of the reaction of 3-or 4-substituted pyridines with benzyl benzenesulfonate in acetone at $35^{\circ}C$ were determined by an electric conductivity method. According to the Hammett plot, the rates were increased the electron donating ability at the $S_N2$ reaction of benzyl benzenesulfonate with pyridine and 4-$NH_2$ pyridine was correlated with ${\sigma}^+$ than Hammett ${\sigma}$ value. This result was explained that $NH_2$ group and N atom in pyridine are largely contribute by resonance. In Br$\"{o}$nsted plot, 4-amino and electron attracting group were deviated from the increasing part at linearity. It was considered to solvent effects on substituents. A mechanistic possibility was proposed to account for the results. Some activation parameters were also calculated.

키워드

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