Abstract
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.
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 $NH_2$기 ${\sigma}$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.