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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 30, Number 2
JKCSEZ 30(2)
April 20, 1986 

Molecular Orbital Analyses on Hammett Substituent Constant (Ⅰ)

Hammett 치환기 상수에 대한 분자궤도론적 해석 (Ⅰ)
Byung-Kak Park, Gab-Yong Lee

박병각, 이갑룡
치환-벤조산, -베젠 및 -나프탈렌의 세 계열에 대해 LCAO MO법으로 Hammett치환기 상수를 해석하였다. Hammett σ값은 이론적으로 유도효과와 공명효과의 독립적인 기여의 합으로 취급됨을 알았다. 즉, 유도효과를 정정유도효과(static inductive effect, Is)와 동적유도효과 (dynamic inductive effect, Id)로 나누어 각각 net charge 및 근사자기편극률 지수로 취하고 공명효과로서 치환 분자와 비치환분자의 HOMO에너지 차(ΔEHOMO)로 취하였으며 계산결과 Hammett σ값은 정적유도효과, 동적유도효과 및 ΔEHOMO의 합에 의존됨을 알았다.

The Hammett's substituent constants were analyzed for the substituted-benzoic acid, -benzene and -naphthalene by LCAO MO method. Hammett's σ-values have been theoretically proved to treat as the sum of independent contribution of inductive effect and resonance effect. That is, Is (static inductive effect) and Id (dynamic inductive effect) corresponding to inductive effect are chosen as net charge and approximate self atom polarizability indices respectively, and ΔEHOMO which is the difference in HOMO energy level between substituted molecule and unsubstituted molecule as resonance effect. In conclusion, it has been found that the observed σ-values depend on the sum of Id, Is and ΔEHOMO.

172 - 180
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