Journal of the Korean Chemical Society (대한화학회지)

Korean Chemical Society (대한화학회)
권호 표지

Kinetics of the Reaction of Phenacyl Bromide with Anilines in Methanol and Dimethylformamide

Phenacyl Bromide와 置換아닐린類와의 反應에 關한 反應速度論的 硏究

  • Soo-Dong Yoh (Department of Chemistry, Teacher's College, Kyungpook National University) ;
  • Doo-Jung Kim (Department of Chemistry, Teacher's College, Kyungpook National University)
  • 여수동 (慶北大學校 師範大學化學科) ;
  • 김두정 (慶北大學校 師範大學化學科)
  • Published : 1981.12.30
Download PDF
⟨ Previous Next ⟩

Abstract

The rates and the activation parameters for the reaction of phenacyl bromide with substituted anilines in methanol and dimethylformamide were measured. The effects of substituted anilines were discussed. The rate of the reaction was increased with the electron donating power of substituent and showed larger value in DMF than in MeOH. The isokinetic relationship was shown between ${\delta}H^{\neq}$ and ${\delta}S^{\neq}$, isokinetic temperature was 539 and $400^{\circ}C$ in MeOH and DMF respectively, but p-nitro aniline was deviated from linearity in both solvents caused by solvent effects. The excellent linear relationship between log k and p$K_a$ of substituted anilines was observed by following equation. log k = 0.57p$K_a$-1.28 (r = 0.996) in MeOH at $45^{\circ}C$, log k = 0.65p$K_a$-0.88 (r = 0.970) in DMF at $45^{\circ}C$. From the Hammett plot, this reaction was a nucleophilic displacement of aniline to phenacyl bromide and the following equation was obtained at $45^{\circ}C$. log k/$k_0$ = -2.00${\sigma}$ + 0.06 (r = 0.985) in MeOH; log k/$k_0$ = -2.22${\sigma}$ + 0.08 (r = 0.995) in DMF. Large deviation of p-nitro aniline in DMF is resulted from solvent effects too. From above results, the substituent effect of this reaction can be described as $S_N2$ mechanism and bond formation more proceeds in DMF relative to MeOH.

페나실브로미드와 치환아닐린류와의 반응속도를 메탄올과 DMF중에서 전기전도도 법으로 측정한 결과 반응속도는 치환기의 전자를 주는 능력이 강할 수록 빨랐으며, 메탄올 속에서 보다 DMF 속에서 더 빨랐다. ${\delta}H^{\neq}$와 ${\delta}S^{\neq}$ 사이에서는 등속 관계가 성립하였으며, 이때 등속 온도는 메탄올에서는 $539^{\circ}K$, DMF에서는 $400^{\circ}K$ 였다. 그러나 p-니트로 아닐린은 용매효과 때문에 직선에서 벗어났다. $Br{\o}nsted$ plot의 경우 메탄올과 DMF에서 log k = 0.57p$K_a$-1.28 (r = 0.996) in MeOH at $45^{\circ}C$; log k = 0.65p$K_a$-0.88 (r = 0.970) in DMF at $45^{\circ}C$,로서 좋은 직선관계가 성립하였다. Hammett${\sigma}$ 도시 결과 이 반응은 아닐린의 친핵치환 반응이었으며, 다음의 식이 얻어졌다. log k/$k_0$ = -2.00${\sigma}$ + 0.06 (r = 0.985) in MeOH; log k/$k_0$ = -2.22${\sigma}$ + 0.08 (r = 0.995) in DMF. 그리고 DMF에서 $4-NO_2$기가 직선에서 벗어났다. 이는 치환기에 의한 용매효과에 기인하는 것이라고 생각된다. 이상의 결과로부터 본 반응의 치환기 효과는 전이상태에서 결합의 형성이 보다 우세한 $S_N2$ 메카니즘으로 진행되고 있으며, 결합의 형성은 DMF 용매에서 더욱 진행되고 있다.

Keywords

References

  1. J. Chem. Soc. K. J. Laidler
  2. J. Amer. Chem. Soc v.61 S. Eagl;J. Warner
  3. J. Amer. Chem. Soc. v.74 R. G. Pearson;S. H., Langer
  4. J. Korean Chem. Soc. S. D. Yoh;K. T. Shim;K. A. Lee
  5. J. Chem. Soc. v.119 J. C. Cox
  6. Org. Chem., Band XIV Beilstein
  7. Phil. Mag v.2 E. A. Guggenheim
  8. J. Chem. Soc., B v.B B. O. Coniglio;D. E. Giles;W. R. McDonald;A. J. Parker
  9. Bull. Chem. Soc., Japan v.37 N. Tokura;Y. Kondo
  10. J. Org. Chem. v.20 Leffler
  11. Catalysis in Chemistry and Enzymology W. P. Jencks
  12. J. Korean Chem. Soc. v.23 K. A. Lee;K. T. Howang;S. D. Yoh
  13. Ph. D. Dissertation, Osaka University v.971 S. D. Yoh
  14. J. Chem. Soc. G. H. Green;J. Kenyon
  15. Bull. Chem. Soc., Japan v.43 T. Matsui;N. Tokura