Kinetics on the Reaction of 1-Adamantyl Fluoroformate with Substituted Pyridines

치환 피리딘류와 1-Adamantyl Fluoroformate의 반응에 대한 속도론적 연구

  • Published : 19990800

Abstract

Rates of 1-adamantyl fluoroformate with substituted pyridines ($3-CH_3,\;4-CH_3,\;H,\;3-Cl,\;3,4-(CH_3)_2,\;3,5-(CH_3)_2$) in methanol have been measured by conductometric method at various temperatures and concentrations. The activation parameters (${\Delta}H^{\neq},\;{\Delta}S^{\neq}$) and Hammett reaction constant (${\rho}$) or Bronsted coefficient (${\beta}$) were evaluated from rate constants. The activation entropies are large and negative, and the activation enthalpies are small and positive. The Hammett reaction constant (${\rho}$) and Bronsted coefficient (${\beta}$) values were -4.15 and 0.63, respectively. From the above results, it may be concluded that this reaction proceeds to a concerted displacement mechanism in methanol.

메탄올 용매내에서 치환 피리딘류($3-CH_3,\;4-CH_3,\;H,\;3-Cl,\;3,4-(CH_3)_2,\;3,5-(CH_3)_2$)와 1-adamantyl fluoroformate의 반응속도를 여러 온도와 농도 조건에서 전도도 방법으로 측정하였다. 이들 반응속도상수로부터 활성화 파라미터(${\Delta}H^{\neq},\;{\Delta}S^{\neq}$)와 Hammett 반응상수(${\rho}$) 및 Bronsted 상관 계수(${\beta}$)를 구하였다. 이 때 ${\Delta}S^{\neq}$는 큰 음의 값을, ${\Delta}H^{\neq}$는 작은 양의 값을 얻었으며, 반응상수 ${\rho}$값과 상관 계수 ${\beta}$값은 각각 -4.15와 0.63이었다. 이러한 결과로부터 본 반응은 협동 치환 메카니즘으로 진행됨을 알 수 있었다.

Keywords

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