Symposium on Chemical Information and Computer Sciences
Symposium on Structure-Activity Relationships
24th Symposium on Chemical Information and Computer Sciences
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Plenary Lecture
How are the linear free energy relationships intrinsically linear?
*Yuho Tsuno
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CONFERENCE PROCEEDINGS FREE ACCESS

Pages JK10

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Abstract

The linear free energy relationships, exemplified by the Hammett and the Broensted equations, are of course empirically based and both assumed to be essentially linear. The Yukawa-Tsuno equation is required to ensure the linearity for the region the original Hammett equation otherwise fails. On the other hand, the establishment of the intrinsic non-linearity in the Broensted relationship has lead to the concept of the selectivity reactivity relationship intimately related to the rate-equilibrium relationship-coordinate shifts of transition state. This elegant concept has now been widely used to the quantitative elucidation of the Hammett-type structure-reactivity correlations in benzyl cationic systems. Non-additivity and non-linearity of substituent effects observed in the polyarylcarbenium systems were elucidated rather elegantly in such a way based on the shifts of transition state coordinate. The most of well-known successful results are criticized, demonstrating no change in transition state position.

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© 2001 The Chemical Society of Japan, The Pharmaceutical Society of Japan
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