Hammett sigma constants
E743332
Hammett sigma constants are substituent constants used in physical organic chemistry to quantify the electronic effects of substituents on reaction rates and equilibria in aromatic systems.
Statements (49)
| Predicate | Object |
|---|---|
| instanceOf |
linear free energy relationship parameter
ⓘ
physical organic chemistry parameter ⓘ substituent constant ⓘ |
| appliesPrimarilyTo | substituents on aromatic rings ⓘ |
| appliesTo |
aromatic systems
ⓘ
substituted benzoic acids ⓘ |
| assumes | linear free energy relationship ⓘ |
| characterizes |
meta substituent effects
ⓘ
para substituent effects ⓘ |
| definedRelativeTo | unsubstituted benzoic acid ⓘ |
| developedInField | physical organic chemistry ⓘ |
| domain |
chemistry
ⓘ
organic chemistry ⓘ |
| hasExtension |
σ+ constants
ⓘ
σI constants ⓘ σR constants ⓘ σ− constants ⓘ |
| hasVariant |
Hammett sigma meta constant
NERFINISHED
ⓘ
Hammett sigma para constant NERFINISHED ⓘ σm ⓘ σp ⓘ |
| introducedBy | Louis Plack Hammett NERFINISHED ⓘ |
| introducedIn | 1937 ⓘ |
| namedAfter | Louis Plack Hammett NERFINISHED ⓘ |
| negativeValuesIndicate | electron-donating substituents ⓘ |
| positiveValuesIndicate | electron-withdrawing substituents ⓘ |
| quantifies |
electronic effects of substituents
ⓘ
inductive effects ⓘ resonance effects ⓘ |
| referenceReaction | ionization of substituted benzoic acids ⓘ |
| referenceSolvent | water ⓘ |
| referenceTemperature | 25 °C ⓘ |
| relatedConcept |
Taft steric constants
ⓘ
Yukawa–Tsuno equation NERFINISHED ⓘ |
| relatedTo |
Hammett equation
NERFINISHED
ⓘ
reaction constant ρ ⓘ |
| symbol | σ ⓘ |
| usedFor |
design of organic molecules
ⓘ
mechanistic interpretation of substituent effects ⓘ quantitative structure–reactivity relationships ⓘ |
| usedIn |
correlation of equilibrium constants
ⓘ
correlation of reaction rates ⓘ linear free energy relationship analysis ⓘ physical organic chemistry ⓘ |
| usedToCorrelate | substituent effects across different reactions ⓘ |
| usedToEstimate |
equilibrium constants
ⓘ
reaction rate constants ⓘ |
| usedWith | reaction constant ρ in Hammett equation ⓘ |
| zeroPointReference | hydrogen substituent ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.