Hammett equation
E743329
linear free-energy relationship
physical organic chemistry concept
quantitative structure–reactivity relationship
The Hammett equation is a fundamental linear free-energy relationship in physical organic chemistry that quantitatively correlates reaction rates and equilibria with the electronic effects of substituents on aromatic compounds.
All labels observed (1)
| Label | Occurrences |
|---|---|
| Hammett equation canonical | 2 |
How this entity was disambiguated
This entity first appeared as the object of triple T8558007 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: Hammett equation Context triple: [Louis P. Hammett, knownFor, Hammett equation]
-
A.
Arrhenius equation
The Arrhenius equation is a fundamental formula in physical chemistry that relates the rate of a chemical reaction to temperature through an exponential dependence on activation energy.
-
B.
Hill equation
The Hill equation is a mathematical expression used in biochemistry and physiology to describe how the binding of ligands to macromolecules or the response to a drug depends on ligand concentration, often capturing cooperative binding behavior.
-
C.
Eyring equation
The Eyring equation is a fundamental expression in chemical kinetics that relates reaction rates to temperature using transition state theory, providing insight into activation parameters such as enthalpy and entropy.
-
D.
Nernst equation
The Nernst equation is a fundamental electrochemistry formula that relates the reduction potential of a half-cell to the standard electrode potential, temperature, and activities (or concentrations) of the chemical species involved.
-
E.
Randles–Ševčík equation
The Randles–Ševčík equation is a fundamental electrochemical relationship that links peak current in cyclic voltammetry to the concentration and diffusion coefficient of a redox-active species.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: Hammett equation Target entity description: The Hammett equation is a fundamental linear free-energy relationship in physical organic chemistry that quantitatively correlates reaction rates and equilibria with the electronic effects of substituents on aromatic compounds.
-
A.
Arrhenius equation
The Arrhenius equation is a fundamental formula in physical chemistry that relates the rate of a chemical reaction to temperature through an exponential dependence on activation energy.
-
B.
Hill equation
The Hill equation is a mathematical expression used in biochemistry and physiology to describe how the binding of ligands to macromolecules or the response to a drug depends on ligand concentration, often capturing cooperative binding behavior.
-
C.
Eyring equation
The Eyring equation is a fundamental expression in chemical kinetics that relates reaction rates to temperature using transition state theory, providing insight into activation parameters such as enthalpy and entropy.
-
D.
Nernst equation
The Nernst equation is a fundamental electrochemistry formula that relates the reduction potential of a half-cell to the standard electrode potential, temperature, and activities (or concentrations) of the chemical species involved.
-
E.
Randles–Ševčík equation
The Randles–Ševčík equation is a fundamental electrochemical relationship that links peak current in cyclic voltammetry to the concentration and diffusion coefficient of a redox-active species.
- F. None of above. chosen
Statements (48)
| Predicate | Object |
|---|---|
| instanceOf |
linear free-energy relationship
ⓘ
physical organic chemistry concept ⓘ quantitative structure–reactivity relationship ⓘ |
| appliesBestTo | meta- and para-substituted benzoic acid derivatives ⓘ |
| appliesTo |
benzoic acid derivatives
ⓘ
reactions involving aromatic substituents ⓘ substituted aromatic compounds ⓘ |
| assumes |
constant reaction mechanism across substituents
ⓘ
dominant electronic effects of substituents ⓘ |
| basedOn | reference reactions of substituted benzoic acids ⓘ |
| category |
Chemical kinetics
ⓘ
Physical organic chemistry theories ⓘ |
| correlates |
electronic effects of substituents
ⓘ
equilibrium constants ⓘ reaction rates ⓘ |
| describes |
linear relationship between log(K) and sigma
ⓘ
linear relationship between log(k) and sigma ⓘ |
| developedBy | Louis Plack Hammett NERFINISHED ⓘ |
| field |
organic chemistry
ⓘ
physical organic chemistry ⓘ |
| hasKeyConcept | linear correlation between structure and free energy changes ⓘ |
| hasMathematicalForm |
log(K/K0) = ρσ
ⓘ
log(k/k0) = ρσ ⓘ |
| hasVariant |
dual-parameter Hammett relationships
ⓘ
sigma-minus (σ⁻) constants ⓘ sigma-plus (σ⁺) constants ⓘ |
| introducedIn | 1937 ⓘ |
| involvesEffect |
inductive effects
ⓘ
resonance effects ⓘ |
| involvesQuantity |
equilibrium constant K
ⓘ
rate constant k ⓘ standard free energy change ΔG° via K ⓘ |
| lessAccurateFor | strongly resonance-interacting ortho substituents ⓘ |
| namedAfter | Louis Plack Hammett NERFINISHED ⓘ |
| quantifies | sensitivity of a reaction to substituent electronic effects ⓘ |
| relatedTo |
Taft equation
NERFINISHED
ⓘ
Yukawa–Tsuno equation NERFINISHED ⓘ linear free-energy relationships ⓘ |
| relates |
reaction constant rho to sensitivity to substituent effects
ⓘ
substituent constant sigma to reactivity ⓘ |
| usedFor |
analyzing substituent effects
ⓘ
correlating equilibrium constants ⓘ predicting relative reaction rates ⓘ |
| usedIn |
design of organic molecules with tuned reactivity
ⓘ
mechanistic studies of organic reactions ⓘ structure–reactivity correlation studies ⓘ |
| usesParameter |
Hammett sigma constant
NERFINISHED
ⓘ
reaction constant rho ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: Hammett equation Description of subject: The Hammett equation is a fundamental linear free-energy relationship in physical organic chemistry that quantitatively correlates reaction rates and equilibria with the electronic effects of substituents on aromatic compounds.
Referenced by (2)
Full triples — surface form annotated when it differs from this entity's canonical label.