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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 28, Number 3
JKCSEZ 28(3)
June 20, 1984 

Nucleophilic Substitution Reactions of Benzyl Bromides and Benzyl Iodide with Anilines in MeOH-MeCN Mixtures

MeOH-MeCN 혼합용매계에서 브롬화벤질 및 요오드화벤질과 아닐린 사이의 친핵성 치환반응
Ikchoon Lee, Se Chul Sohn, Ho Bong Song, Byung Choon Lee

이익춘, 손세철, 송호봉, 이병춘
메탄올-아세토니트릴 혼합용매계에서 파라치환된 브롬화 벤질 및 요오드화 벤질과 아닐린 치환체 사이의 친핵성 치환반응을 35.0℃에서 연구하였다. Hammett관계식, Bronsted 관계식을 이용하여 반응 선택성 파라미터인 ρN, ρC 및 Brψnsted β값을 구했으며 분광용매화 관계식의 계수 a, s 등을 구했다. 분광용매화 관계식의 계수 a, s 및 a/s값으로부터 혼합용매의 π*효과가 본 반응에 크게 작용함을 알았다. PES 모형을 적용하여 본 반응이 dissociative SN2메카니즘으로 진행됨을 알 수 있었으며 이탈기 효과의 논의에는 PES모형이 실험결과와 잘 일치하지 않음을 알 수 있었다. 양자역학적 해석방법을 이용하여 본 반응의 전이상태 변화를 논의했으며 실험결과와 잘 일치함을 알 수 있었다.

Kinetic studies for the nucleophilic substitution reactions of para-substituted benzyl bromides and benzyl iodide with anilines were carried out in MeOH-MeCN mixtures at 35.0℃. Hammett ρN, ρC, Brψnsted β and solvatochromic correlation coefficient a, s values were determined in order to clarify the transition state variations caused by changing nucleophiles, substituents, leaving group and solvents. The results of solvatochromic equation showed that π*effect was a dominant factor for the reaction systems studied. It was shown that the reaction proceeds via the dissociative SN2 mechanism using the potential energy surface model approach. The potential energy surface model approach however failed to account for the transition state variation due to leaving group changes. The quatum mechanical approach showed that kinetic results were consistent with proposed dissociative SN2 mechanism.

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