Enthalpy of dissociation of nitric acid in aqueous sulphuric acid and its relation to the activation energies of encounter-controlled nitrations

Hartshorn, S. R.; Moodie, R. B.; Stead, Keith

doi:10.1039/p29720000127

Cited by 6 publications

(3 citation statements)

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“…Furthermore, for mesitylene, the typical value expected for an encounter limited reaction has also been found. 6,37 The linear relationship between k 2 Њ rates that has been observed for analogous compounds undergoing nitration in aqueous acid media (i.e. H 2 SO 4 ) and in the gas phase 10 or in different aqueous acids (i.e.…”

Section: Theoretical Nitration Rates (Log K 2 њ)mentioning

confidence: 94%

Thermodynamic nitration rates of aromatic compounds. Part 4. Temperature dependence in sulfuric acid of HNO3→NO2+ equilibrium, nitration rates and acidic properties of the solvent †

Marziano¹,

Tomasin²,

Tortato³

et al. 1998

J. Chem. Soc., Perkin Trans. 2

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Section: Theoretical Nitration Rates (Log K 2 њ)mentioning

confidence: 94%

Thermodynamic nitration rates of aromatic compounds. Part 4. Temperature dependence in sulfuric acid of HNO3→NO2+ equilibrium, nitration rates and acidic properties of the solvent †

Marziano¹,

Tomasin²,

Tortato³

et al. 1998

J. Chem. Soc., Perkin Trans. 2

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“…In analogy with the current views on such diffusioncontrolled processes for which the classic selectivity relationship breaks down [25], we suggest that the present gas-phase results provide strong evidence for a kinetic model involving the primary, irreversible formation of an "encounter pair" between the electrophile and the substrate. In the gase phase, the process is strongly favoured by the significant decrease of the electrostatic potential energy caused by the distribution of the positive charge, initially concentrated on (CH 3 ) 2 F + , over a much larger number of atoms, and it is likely to involve the π-electrons system, even though no direct evidence pointing to the π complex postulated by OLAH [26] is presently available.…”

Section: The Alkylation Processmentioning

confidence: 50%

Gas Phase Methylation of Polymethylbenzenes by Dimethylfluoronium Ions. A Radiolytic and Mass Spectrometric Study

Aliprandi¹,

Cacace²,

Cipollini³

1983

Radiochimica Acta

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The alkylation of trimethyl-and tetramethylbenzenes by dimethylfluoronium ions, (CH 3 ) 2 F + , has been studied both by radiolytic techniques in gaseous CH 3 F at atmospheric pressure and by CH 3 F chemical ionization mass spectrometry.In particular, the substrate selectivity of the ionic methylation has been studied over an exceptionally wide pressure range. The mechanism of the gas-phase alkylation is discussed. The observed lack of substrate selectivity, and the appreciable positional selectivity, are rationalized with a kinetic model that could be of general value to aromatic substitution by very reactive gaseous cations.

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“…where E2 is the activation energy for reaction 4 and AH is the enthalpy change for equilibrium 3. It is likely that E2 depends more on the aromatic than on the medium, and that the variation of E2 is largely due to AH decreasing with increasing acidity (Hartshorn et al, 1972).…”

Section: Discussionmentioning

confidence: 99%

Dependence of the rate constant and activation energy of aromatic nitration on mixed acid composition

Field¹,

Strachan²

1982

Ind. Eng. Chem. Prod. Res. Dev.

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The dependence of the second-order rate constant for homogeneous aromatic nitration, k2, on mixed acid composition has been determined for three aromatics of differing reactivity, namely toluene, chlorobenzene, and p-dichlorobenzene. This has allowed contours of constant k2 to be constructed over the portion of the H2S04-HN03-H20 mol % triangular diagram in which lie the mixed acid compositions normally employed in Industrial nitration. The contours are found to be near linear and to run almost perpendicular to the H20-H2S04 side of the diagram. With chlorobenzene activation energies have also been determined. The activation energy is found to vary with mixed acid composition and does not remain constant along a contour of constant k2. Along the H20-H2S04 side of the diagram over the range 26 to 42 mol % H2S04, the activation energy is found to decrease by ~0.65 Real mol"1 for every 1% increase in mol % H2S04. The results and their implications for inductrial reactors are discussed.

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Enthalpy of dissociation of nitric acid in aqueous sulphuric acid and its relation to the activation energies of encounter-controlled nitrations

Cited by 6 publications

References 0 publications

Thermodynamic nitration rates of aromatic compounds. Part 4. Temperature dependence in sulfuric acid of HNO3→NO2+ equilibrium, nitration rates and acidic properties of the solvent †

Thermodynamic nitration rates of aromatic compounds. Part 4. Temperature dependence in sulfuric acid of HNO3→NO2+ equilibrium, nitration rates and acidic properties of the solvent †

Gas Phase Methylation of Polymethylbenzenes by Dimethylfluoronium Ions. A Radiolytic and Mass Spectrometric Study

Dependence of the rate constant and activation energy of aromatic nitration on mixed acid composition

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