Yukawa-Tsuno equation

Term · Chemistry · MLC-T-CHM-012787

A multiparameter extension of the Hammett equation used in physical organic chemistry to describe substituent effects on the rates or equilibria of reactions involving aromatic compounds. It explicitly accounts for enhanced resonance effects by introducing a term, r(σ⁺ − σ), that quantifies the degree of direct resonance interaction between a substituent and the reaction center. The parameter r represents the extent of charge development at the transition state relative to that in the cumyl cation.

Table 1. Record
Identifier	MLC-T-CHM-012787
Field	Chemistry
Subject	Organic and Biomolecular Chemistry
References	PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1176 (https://doi.org/10.1351/pac199466051077)
See also	Ρ-value; Hammett equation; Mesomeric effect; Σ-constant

Record as JSON

{
  "id": "MLC-T-CHM-012787",
  "term": "Yukawa-Tsuno equation",
  "field": "Chemistry",
  "definition": "A multiparameter extension of the Hammett equation used in physical organic chemistry to describe substituent effects on the rates or equilibria of reactions involving aromatic compounds. It explicitly accounts for enhanced resonance effects by introducing a term, r(σ⁺ − σ), that quantifies the degree of direct resonance interaction between a substituent and the reaction center. The parameter r represents the extent of charge development at the transition state relative to that in the cumyl cation.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "ρ-value",
    "Hammett equation",
    "mesomeric effect",
    "σ-constant"
  ],
  "references": [
    "PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1176 (https://doi.org/10.1351/pac199466051077)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/yukawa-tsuno-equation/"
}

Record 13,635 of 13,676 in Chemistry terminology (MLC-0109). Request the full dataset.