Definition of Yukawa-Tsuno equation

A multiparameter extension of the Hammett equation to quantify the role of enhanced resonance effects on the reactivity of meta- and para-substituted benzene derivatives, e.g.

lg k = lg ko + [rho] [sigma] + r ( [sigma] + - [sigma] )]

The parameter r gives the enhanced resonance effect on the scale ( [sigma] +- [sigma] ), or ( [sigma] -- [sigma] ), respectively.

See also [rho] -value, [sigma] -constant. See YUKAWA and TSUNO (1959); SHORTER (1973).

Z-value

See below under Z-value.

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