Journal of the Korean Chemical Society (대한화학회지)

Korean Chemical Society (대한화학회)
권호 표지

Substituent Effects on the Leaving Groups in Benzyl Arenesulfonates

Benzyl Arenesulfonate의 離脫基의 置換基效果에 關한 硏究 (第 1 報)

  • Yoh Soo Dong (Department of Chemistry, Teacher's College, Kyungpook National University)
  • 여수동 (慶北大學校 師範大學 化學科)
  • Published : 1975.04.30
Download PDF
⟨ Previous Next ⟩

Abstract

Determination has been made of the kinetics of the reaction of benzyl arenesulfonates with pyridine in acetone. The substituent effects of the leaving groups in benzyl arenesulfonates are correlated by Hammett equations, with the exception of p-MeO and $p-NO_2$ groups, where the electron attracting substituents in the benzyl arenesulfonate increase the rate. The substituent effects of the leaving groups are as expected due to the nucleophilic attack of amine on the benzyl carbon atom. This can be understood in terms of changes in bond formation (C-N) and bond breaking (C-O) in the transition state with charges in electron-attracting ability of the substituents. The predicted substituent effects may indicate a small increase in bond formation and thus a tighter transition state, in benzyl p-bromobenzene sulfonate than in benzyl p-nitrobenzenesulfonate. Predicting made by Thornton concerning the substituent effects on $S_N2$ transition state structures agrees with the changes in bond formation and bond breaking.

Benzyl arenesulfonate와 피리딘과의 아세톤 용매중에서의 反應速度를 測定하였다. Benzyl arenesulfonate의 離脫基의 치환기효과는 p-MeO基 및 $p-NO_2$기를 除外하고는 Hammett 式에 잘 적용되었으며, 전자끄는기는 반응속도를 증가시켰다. 離脫基의 치환효과는 벤질炭素에 아민이 親核的으로 공격하여 전이상태에서 치환기의 電子끄는 능력이 C-N 結合의 形成과 C-O結合의 쪼개짐에 변화를 주고 있다는 사실로서도 설명이 되어진다. 치환기효과는 benzyl p-bromobenzeneslfonate가 benzyl p-nitrobenzenesulfonate보다 N-C結合이 tight 한 전이상태의 구조를 가지고 있음을 말해주며 이는 結合의 형성과 쪼개짐에 있어 Thornton의 $S_N2$전이상태 구조의 예상과도 잘 符合된다.

Keywords

References

  1. Can. J. Chem. v.31 R. E. Robertson
  2. Organic Solvents J. A. Riddick
  3. Bull. Chem. Soc. Japan v.45 Y. Yukawa(et al.)
  4. Pure Appl. Chem. v.13 J. F. Coetzee
  5. J. Amer. Chem. Soc. v.75 W. D. Emmons;A. F. Ferris
  6. J. Amer. Chem. Soc. v.92 A. Streitwieser(et al.)
  7. J. Korean Chem. Soc. v.13 S. D. Yoh;D. S. Lee;S. Y. Hong
  8. J. Korean Chem. Soc. v.16 S. Y. Hong;S. D. Yoh
  9. Kinetics and Mechanism A. A. Frost;R. G. Pearson
  10. J. Amer. Chem. Soc. v.70 M. S. Morgan;L. H. Cretcher
  11. J. Amer. Chem. Soc. v.55 L. P. Hammett;M. K. Pfluger
  12. Physical Organic Chemistry L. P. Hammett
  13. J. Org. Chem. v.23 D. H. McDaniel;H. C. Brown
  14. Nippon Kagaku Kaishi v.6 M. Tsuruta(et al.)
  15. J. Amer. Chem. Soc. v.89 E. R. Thornton
  16. J. Amer. Chem. Soc. v.92 J. C. Harris;J. L. Kurtz