Extended Hammett equation

{
  "id": "MLC-T-CHM-004256",
  "term": "Extended Hammett equation",
  "field": "Chemistry",
  "definition": "A modification of the original Hammett equation that incorporates additional substituent parameters to account for more complex electronic effects in reaction rates and equilibrium constants. This equation separates the electronic effects of substituents into inductive, resonance, and sometimes steric components, allowing for a more nuanced analysis of structure-reactivity relationships. It is expressed as a linear free-energy relationship, correlating reaction rates or equilibrium constants with these substituent parameters, often including separate terms for field/inductive and resonance effects.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "Hammett equation",
    "dual substituent-parameter equation"
  ],
  "references": [
    "PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1114 (https://doi.org/10.1351/pac199466051077)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/extended-hammett-equation/"
}