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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 25, Number 6
JKCSEZ 25(6)
December 20, 1981 

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

Phenacyl Bromide와 치환아닐린류와의 반응에 관한 반응속도론적 연구
Author
Soo-Dong Yoh, Doo-Jung Kim

여수동, 김두정
Keywords
Abstract
페나실브로미드와 치환아닐린류와의 반응속도를 메탄올과 DMF중에서 전기전도도 법으로 측정한 결과 반응속도는 치환기의 전자를 주는 능력이 강할 수록 빨랐으며, 메탄올 속에서 보다 DMF 속에서 더 빨랐다. ΔH≠와 ΔS≠ 사이에서는 등속 관계가 성립하였으며, 이때 등속 온도는 메탄올에서는 539。K, DMF에서는 400。K 였다. 그러나 p-니트로 아닐린은 용매효과 때문에 직선에서 벗어났다. Bronsted plot의 경우 메탄올과 DMF에서 log k = 0.57pKα-1.28 (r = 0.996) in MeOH at 45℃; log k = 0.65pKα-0.88 (r = 0.970) in DMF at 45℃,로서 좋은 직선관계가 성립하였다. Hammettσ 도시 결과 이 반응은 아닐린의 친핵치환 반응이었으며, 다음의 식이 얻어졌다. log k/k0 = -2.00σ + 0.06 (r = 0.985) in MeOH; log k/k0 = -2.22σ + 0.08 (r = 0.995) in DMF. 그리고 DMF에서 4-NO2기가 직선에서 벗어났다. 이는 치환기에 의한 용매효과에 기인하는 것이라고 생각된다. 이상의 결과로부터 본 반응의 치환기 효과는 전이상태에서 결합의 형성이 보다 우세한 Sn2 메카니즘으로 진행되고 있으며, 결합의 형성은 DMF 용매에서 더욱 진행되고 있다.

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 ΔH≠ and ΔS≠, isokinetic temperature was 539 and 400℃ 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 pKα of substituted anilines was observed by following equation. log k = 0.57pKα-1.28 (r = 0.996) in MeOH at 45℃, log k = 0.65pKα-0.88 (r = 0.970) in DMF at 45℃. From the Hammett plot, this reaction was a nucleophilic displacement of aniline to phenacyl bromide and the following equation was obtained at 45℃. log k/k0 = -2.00σ + 0.06 (r = 0.985) in MeOH; log k/k0 = -2.22σ + 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 SN2 mechanism and bond formation more proceeds in DMF relative to MeOH.

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376 - 382
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