Gas-phase ion-molecule nitration chemistry: the nitration of aromatic radical cations by nitrogen dioxide

Schmitt, Robert J.; Buttrill, S. E.; Ross, David S.

doi:10.1021/ja00316a017

Cited by 33 publications

(18 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The above observation is in contrast to that of Buttrill and co-workers (18) who found that the arenium ion resulting from the addition of mesitylene' to NO2, CgH12N02+, transfers a proton "very rapidly" to mesitylene. If the arenium ion has a structure analogous to III, with NO, meta to the site of the proton, then its destabilizing influence should not be too much greater than that of CC13 since at this site only the inductive effect is operative (19 We have previously reported (20) that when CH3+ or C2Hs+ adds to mesitylene, the resulting arenium ion does transfer a proton, albeit slowly, to mesitylene.…”

Section: Ch3 Icontrasting

confidence: 93%

The gas phase reactions of the trichloromethylium ion with alkyl aromatics, studied by high pressure mass spectrometry

Stone¹,

Moote²,

Wojtyniak³

1985

Can. J. Chem.

View full text Add to dashboard Cite

The reactions of trichloromethylium (CCl3+) with benzene and the lower alkyl aromatics (ArH) have been studied by high pressure mass spectrometry at pressures in the range 2–4 Torr and temperatures from 300 to 560 K. The only two primary products are the adduct ArHCCl3+ and ArCCl2+, which is formed by loss of HCl from the adduct. The relative yields of adduct increase with increasing number of methyl substituents on the aromatic ring (benzene → mesitylene). The disappearance of CCl3+ is kinetically second order with specific rate constants increasing from benzene to mesitylene, the latter reacting essentially at every ion–molecule collision. All rate constants are fairly large (>1010 cc molecule−1 s−1) and show negative temperature coefficients. ArCCl2+ is unreactive but ArHCCl3+ reacts further by proton transfer to ArH.

show abstract

Section: Ch3 Icontrasting

confidence: 93%

The gas phase reactions of the trichloromethylium ion with alkyl aromatics, studied by high pressure mass spectrometry

Stone¹,

Moote²,

Wojtyniak³

1985

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…In fact, even nonconventional nitration techniqueselectrochemical, gas phase, and photoinduced nitration,which have provided important mechanistic indications, have not made it possible to produce decisive evidence in favor of path A or B, since more competing processes may occur; nor have the studies of Ridd and co-workers, based on CIDNP (chemically induced dynamic nuclear polarization), been of help: despite the decisive role of that technique in proving that the reaction of aromatics with the nitrosonium ion occurs via an ET step, it does not permit a definitive assessment of the question, because the absence of nuclear polarization does not necessarily imply the absence of a radical pair on the reaction path, since a significant separation of the radical pair must occur for a CIDNP effect to be observed 10b…”

Section: Introductionmentioning

confidence: 99%

On the Occurrence of an Electron-Transfer Step in Aromatic Nitration

Peluso

1996

J. Phys. Chem.

View full text Add to dashboard Cite

The possibility that aromatic nitration proceeds via the formation of an electron donor−acceptor complex and its possible evolution in a “contact” radical pair is discussed on the basis of ab-initio configuration interaction computations on benzene/toluene NO2 + systems. The analysis of the region of the potential energy hypersurfaces corresponding to the two reactants kept at van der Waals distances shows the existence of a conical intersection between the ground state and the first excited charge transfer singlet, leading to electron transfer from the aromatic substrate to the nitronium ion. The activated state for electron transfer (ET) might then be identified with the “early” transition state invoked by Olah to explain the high positional selectivity of substitution in spite of a low substrate selectivity. The retention of positional selectivity at encounter-limited rates may then be ascribed to the fact that the formation of a Wheland intermediate corresponds to a radical pair recombination and as such is spin density driven. The objection that ET is a kinetically difficult step is met, the computed upper limit of the barrier to ET being 13 kcal/mol for the toluene substrate.

show abstract

“…Em princípio, experimentos em fase gasosa eliminam os efeitos do meio, tais como solvatação, contra-íon, difusão, etc., de forma que os resultados em fase gasosa devem representar as características que são inerentes apenas às espécies (Equação 5). Apenas as espécies altamente desativadas, tetrafluoradas por exemplo, não sofrem nitração via cátion radical aromático (Equação 6) 57 . Observou-se ainda que o íon intermediário ArHNO 2 + transfere um próton para uma base, piridina por exemplo, indicando tratar-se de um íon arênio 57 .…”

Section: Nitração Em Fase Gasosaunclassified

“…Apenas as espécies altamente desativadas, tetrafluoradas por exemplo, não sofrem nitração via cátion radical aromático (Equação 6) 57 . Observou-se ainda que o íon intermediário ArHNO 2 + transfere um próton para uma base, piridina por exemplo, indicando tratar-se de um íon arênio 57 . Os trabalhos mais completos em fase gasosa foram publicados pelo grupo de Cacace que analisou a reação de nitração do benzeno através de uma combinação de métodos de espectroscopia de massas, utilizando como agente nitrante o nitrato de metila protonado, em essência o íon nitrônio solvatado com uma molécula de metanol [58][59][60][61] .…”

Section: Nitração Em Fase Gasosaunclassified

Nitração aromática: substituição eletrofílica ou reação com transferência de elétrons?

Cardoso

Carneiro

2001

Quím. Nova

View full text Add to dashboard Cite

Gas-phase ion-molecule nitration chemistry: the nitration of aromatic radical cations by nitrogen dioxide

Cited by 33 publications

References 1 publication

The gas phase reactions of the trichloromethylium ion with alkyl aromatics, studied by high pressure mass spectrometry

The gas phase reactions of the trichloromethylium ion with alkyl aromatics, studied by high pressure mass spectrometry

On the Occurrence of an Electron-Transfer Step in Aromatic Nitration

Nitração aromática: substituição eletrofílica ou reação com transferência de elétrons?

Contact Info

Product

Resources

About