The borderline between the classical and the electron transfer process in nitration by the nitronium ion

Johnston, James F.; Ridd, John H.; Sandall, John P. B.

doi:10.1039/c39890000244

Cited by 9 publications

(3 citation statements)

References 2 publications

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“…However resonance theory fails to provide an explanation for the significant orthoreactivity observed in this molecule. 33,34,36 This reactivity pattern is difficult rationalise, yet the IE surfaces correspond with this observation and show significant streaking of lower IE energies from the meta positions across the ortho positions (but much less so across the para position). At this point it is worth mentioning that the largest HOMO lobe lies over the para position in benzonitrile 3, (Fig.…”

Section: Ionisation Energy Surfaces For Visualising Regioselectivity mentioning

confidence: 85%

Aromatic reactivity revealed: beyond resonance theory and frontier orbitals

Brown

Cockroft

2013

Chem. Sci.

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Section: Ionisation Energy Surfaces For Visualising Regioselectivity mentioning

confidence: 85%

Aromatic reactivity revealed: beyond resonance theory and frontier orbitals

Brown

Cockroft

2013

Chem. Sci.

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“…The idea that electron transfer is involved in nitration has a long history in the literature . In reactions of highly electron-rich aromatics, Kochi and others were able to strongly support the viability of such mechanisms. , With less electron-rich arenes such as toluene, however, Eberson argued that the uphill electron transfer would be far too slow to account for the observed rates of reactions . Notably, the reactivity of aromatics correlates well with the stability of σ-complexes on a broad scale that includes both electron-rich and electron-poor aromatics .…”

Section: Introductionmentioning

confidence: 99%

Dynamics and the Regiochemistry of Nitration of Toluene

Nieves‐Quinones

Singleton

2016

J. Am. Chem. Soc.

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The regiochemistry of the nitration of toluene by NO2+BF4− in dichloromethane is accurately predicted from trajectories in explicit solvent. Simpler models and approaches based on transition state theory fail to account for the selectivity. Potential of mean force calculations find no free-energy barrier for reaction of the toluene/NO2+BF4− encounter complex, yet the trajectories require an extraordinary 3 ps to descend an exergonic slope. The selectivity is decided late in long trajectories because their completion requires solvent and counterion reorganization. The normal descriptive understanding of the regiochemistry based on transition-state energies is unsupported.

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“…Although the nitration of naphthalene predominantly follows the arenium intermediate pathway, application of 15N CIDNP techniques indicates that there is a small but significant contribution from the alternative single-electron transfer route. 31 In carbon tetrachloride, nitrogen dioxide nitrates naphthalene by a free radical mechanism; mononitration occurs predominantly in the 1 -position and there is also appreciable formation of the unusual 1,3and 2,3-dinitronaphthalenes. The product ratios obtained resemble those observed for nitronaphthalenes formed by atmospheric pollution, and suggest that these may also arise by free radical processes.…”

Section: F J Imentioning

confidence: 99%

Chapter 7. Aromatic compounds

Coutts¹

1989

Annu. Rep. Prog. Chem., Sect. B

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Benzene and the Phenyl Ring.-As a contribution to the continuing search for methods of quantifying aromaticity in molecules, Zhou and Parr' have expanded their recent suggestion that absolute hardness (or HOMO-LUMO gap) is such a measure by the introduction of a new concept of relative hardness (relative to a defined hypothetical acyclic reference structure). For over 200 cyclic conjugated molecules predictions of aromaticity using relative and absolute hardness give results in agreement with other measures of aromaticity, and it is concluded that relative hardness is a particularly good index for identifying aromatic, non-aromatic, and anti-aromatic character.The distortion from planarity of highly substituted 1,3,5-tris(diethylamin0)-2,4,6trinitrobenzene, determined by X-ray crystallography, has been discussed* in terms of steric and electronic factors; in the ground state the molecule is in a boat form, the result of cooperative non-bonded steric repulsion and strong push-pull conjugation, while in solution it exists as boat C3 and twist C2 conformers. Application3 of supersonic molecular jet laser spectroscopy has allowed the 'trapping' and structural determination of the most stable conformers of a number of methoxybenzenes. In each case the methoxy group lies in the plane of the ring; curiously, in the methoxytoluenes the meta isomer shows a large barrier to methyl rotation, but the methyl groups in the ortho and para isomers are free rotating. Results of a large MRCDI ab initio calculation show4 for the lowest triplet state of the free benzene molecule that the hexagonal conformation is unstable and lies 800cm-' above an almost cylindrical trough.The influence of a P-aryl substituent on the reactivity of aryl alkyl derivatives has long been attributed to phenyl participation in carbocation formation. Evidence for the formation of the simplest example (1) in the gas phase has recently been( 1 )

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The borderline between the classical and the electron transfer process in nitration by the nitronium ion

Abstract: 15N N.m.r. studies indicate that the electron transfer process makes a small but significant contribution to the nitration of naphthalene by the nitronium ion.

Cited by 9 publications

References 2 publications

Aromatic reactivity revealed: beyond resonance theory and frontier orbitals

Aromatic reactivity revealed: beyond resonance theory and frontier orbitals

Dynamics and the Regiochemistry of Nitration of Toluene

Chapter 7. Aromatic compounds

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