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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 30, Number 3
JKCSEZ 30(3)
June 20, 1986 

 
Title
Cooperative Effects of Solvatochromic Parameters on the Ionizations of tert-Butyl Halides in MeOH-1,1,2,2-Tetrachloroethane Mixtures

MeOH-1,1,2,2-Tetrachloroethane 혼합용매에서 tert-Butyl Halides의 이온화에 미치는 분광용매화변수들의 협동효과
Author
Yeol Sakong, Shi Choon Kim, Jae Bum Choo

사공렬, 김시준, 주재범
Keywords
Abstract
MeOH-1,1,2,2-tetrachloroethane 혼합용매에서 할로겐화삼차부틸(t-BuCl, t-BuBr, t-BuI)의 가메탄올 분해반응을 속도론적으로 연구하였으며, 이온화에 미치는 용매효과를 고찰하기 위하여 6가지 indicater를 이용한 분광용매화비교법을 적용하였다. 이결과 할로겐화삼차부틸의 가메탄올 분해반응에 미치는 용매화의 작용은 용매의 극상-편극성에 기인되는 상호작용이 주된 것이긴 하지만 halide leaving group의 living ability에 미치는 electrophilic assistance와 t-Butyl 양이온쪽에 대한 nucleophilic assistance도 상당히 작용함을 알 수 있다. 특히 hydrogen bonding에 의한 electrophilic assistance는 basicity가 큰 leaving group일수록 커지며 (I- < Br- < Cl-), 탄소 중심일수록 커짐을 밝힐 수 있었다. (t-BuCl < t-BuBr < t-BuI)

Kinetic studies for the methanolysis of tert-butyl halides (t-BuCl, t-BuBr, t-BuI) were carried out in MeOH-1,1,2,2-tetrachloroethane mixtures. The solvatochromic comparison method was used with six indicators to analyze solvent effects on the ionizations of tert-butyl halides. It was shown that the cooperative effect of solvent polarity-polarizability was the most important factor influenced on the methanolysis rates of tert-butyl halides, but the electrophilic assistance for halide leaving group and the nucleophilic assistance for tert-butylium ion were considerably influential, too. And it was found that the electrophilic assistance caused by hydrogen bonding and the nucleophilic assistance for carbon center were stronger for more basic leaving group (I- < Br- < Cl-) and more polarizable leaving group(t-BuCl < t-BuBr < t-BuI), respectively.

Page
265 - 272
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