Concept
Reaction mechanisms
6 studies2 discoveries
A reaction mechanism is the sequence of elementary steps, intermediates and transition states that convert reactants to products — tested by kinetics, isotopes, dynamics or computation against experiment.
Mechanism is how chemists explain why a reaction is fast, selective or fails — not just that it happened.
Studies
6
Findings
5
7 supporting · 0 challenging · 0 qualifying citations
Open tensions
1
Currently
What we know
- This library holds 6 empirical chemistry papers on reaction mechanisms with isolated findings, rates or spectra rather than reviews.
- Sensitive assays show microdroplet H2O2 comes from dissolved O2 reacting at solid–water interfaces, not from ultrahigh fields at the air–water surface.
- FT-ICR and DFT show iron(IV)–oxo porphyrin cation radicals epoxidize olefins with rates that track substrate ionization energy.
- Even with extra methyl groups on the alkyl iodide, Cl− and CN− still show a direct backward SN2 rebound channel at high collision energy rather than fully statistical dynamics.
- DFT plus deuterium controls show (PhO)3PAu carbenes add at phenol para-C, then two waters shuttle the proton, beating O–H insertion.
Largest unresolved question
Computed pathways and experimental branching can disagree; a rate constant on one model substrate does not fix the mechanism of a catalytic cycle.
Common misconceptions
If DFT finds a low barrier, that is the mechanism.
Computation is a hypothesis until it matches rates, isotopes or product ratios.
Related
Claim ledger
What the evidence shows
Drawn from 6 studies in this library. Mix labels say which citation roles are present; they are not a strength score. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope.
This library holds 6 empirical chemistry papers on reaction mechanisms with isolated findings, rates or spectra rather than reviews.
- H2O2 is not born at the air–water droplet surface
- Gas-phase rates of heme-model olefin epoxidation
- Direct SN2 rebound survives bulky alkyl iodides
Study Role Design N Population Outcome H2O2 is not born at the air–water droplet surface Supports OtherLow-LOD H2O2 assays comparing bulk water, N2 condensates, humidifiers, and glass–water contacts Analytical chemistry controls — no sample N Bulk water, condensed microdroplets, and solid–water interfaces Whether spontaneous micromolar H2O2 forms at the air–water interface Gas-phase rates of heme-model olefin epoxidation Supports OtherGas-phase FT-ICR bimolecular rate constants for [FeIV(O)(TPFPP+·)]+ with olefins plus DFT Physical-organic kinetics panel of olefins — not a sample-N study Gas-phase iron-oxo porphyrin cation and olefin substrates Epoxidation rate constants and efficiency versus olefin ionization potential Direct SN2 rebound survives bulky alkyl iodides Supports OtherCrossed-beam velocity-map imaging of Cl−/CN− with alkyl iodides plus computed SN2/E2 barriers Collision energies 0.4, 1.1, and 1.9 eV across CH3I, CH3CH2I, and (CH3)2CHI Gas-phase ion–molecule SN2/E2 reactions Direct backward SN2 rebound persists even with steric methylation and outcompetes E2 above 1 eV Sensitive assays show microdroplet H2O2 comes from dissolved O2 reacting at solid–water interfaces, not from ultrahigh fields at the air–water surface.
FT-ICR and DFT show iron(IV)–oxo porphyrin cation radicals epoxidize olefins with rates that track substrate ionization energy.
Even with extra methyl groups on the alkyl iodide, Cl− and CN− still show a direct backward SN2 rebound channel at high collision energy rather than fully statistical dynamics.
DFT plus deuterium controls show (PhO)3PAu carbenes add at phenol para-C, then two waters shuttle the proton, beating O–H insertion.
Debates
Tensions and limits
Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes.
Computed pathways and experimental branching can disagree; a rate constant on one model substrate does not fix the mechanism of a catalytic cycle.
Computed pathways and experimental branching can disagree; a rate constant on one model substrate does not fix the mechanism of a catalytic cycle.
Study Role Design N Population Outcome H2O2 is not born at the air–water droplet surface Supports OtherLow-LOD H2O2 assays comparing bulk water, N2 condensates, humidifiers, and glass–water contacts Analytical chemistry controls — no sample N Bulk water, condensed microdroplets, and solid–water interfaces Whether spontaneous micromolar H2O2 forms at the air–water interface Gas-phase rates of heme-model olefin epoxidation Supports OtherGas-phase FT-ICR bimolecular rate constants for [FeIV(O)(TPFPP+·)]+ with olefins plus DFT Physical-organic kinetics panel of olefins — not a sample-N study Gas-phase iron-oxo porphyrin cation and olefin substrates Epoxidation rate constants and efficiency versus olefin ionization potential
PaperFren reads this as a limit on how far one study travels — different assays, populations, or outcomes — not a forced fight between papers.
Timeline
How understanding moved
Study years are when the paper was published. Evidence edits are dated changes to this page's claims. Explanations are when PaperFren added a Discovery — not a claim that the science happened that day.
2026
Concept page published
Reaction mechanisms
- Quantum yields of 44 and 77 say these photoredox reactions run radical chains
- Six thousand reactions an hour changes which chemistry questions can be asked
Change log
What changed
Dated edits to this page's evidence: studies added or removed from a claim, claims added or withdrawn, and new explanations tagged here. Coverage edits are distinct from reviewed research changes and corrections. Dates record PaperFren updates; study publication dates appear in the timeline.
- Quantum yields of 44 and 77 say these photoredox reactions run radical chainsEvidence: Strengthening
- Coverage updated · Concept page published
Papers
6 studies in this library bear on Reaction mechanisms, ordered by citations.
- Gas-phase rates of heme-model olefin epoxidation
FT-ICR and DFT show iron(IV)–oxo porphyrin cation radicals epoxidize olefins with rates that track substrate ionization energy.
- H2O2 is not born at the air–water droplet surface
Sensitive assays show microdroplet H2O2 comes from dissolved O2 reacting at solid–water interfaces, not from ultrahigh fields at the air–water surface.
- Why gold carbenes hit phenol para-C–H
DFT plus deuterium controls show (PhO)3PAu carbenes add at phenol para-C, then two waters shuttle the proton, beating O–H insertion.
- Direct SN2 rebound survives bulky alkyl iodides
Even with extra methyl groups on the alkyl iodide, Cl− and CN− still show a direct backward SN2 rebound channel at high collision energy rather than fully statistical dynamics.
- Why acetaldehyde kills the DERA aldolase
Crotonaldehyde, the acetaldehyde aldol product, covalently bridges catalytic K167 to nearby C47; a C47M mutant survives 300 mM acetaldehyde.
- Ultrasound microdroplets make H2O2 from dissolved O2
Water-in-hexadecane droplets under 40 kHz ultrasound produce H2O2 at 0.24 mM min−1, almost entirely at the oil–water interface via superoxide from dissolved oxygen.
Compare studies
Select 2–10 studies. Design and N are labels, not a ranking.
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Questions
What is still open
Computed pathways and experimental branching can disagree; a rate constant on one model substrate does not fix the mechanism of a catalytic cycle.
Ask PaperFren about Reaction mechanisms
Study this conceptflashcards and short-answer questions
What does reaction mechanisms mean in this chemistry library?
A reaction mechanism is the sequence of elementary steps, intermediates and transition states that convert reactants to products — tested by kinetics, isotopes, dynamics or computation against experiment.
Name one empirical finding from the reaction mechanisms papers.
Sensitive assays show microdroplet H2O2 comes from dissolved O2 reacting at solid–water interfaces, not from ultrahigh fields at the air–water surface.
What is a limit of reaction mechanisms evidence here?
Computed pathways and experimental branching can disagree; a rate constant on one model substrate does not fix the mechanism of a catalytic cycle.