Proton nuclear magnetic resonance studies of the products formed by polynitrobenzenes when dissolved in liquid ammonia

Chudek, J. A.; Foster, R.

doi:10.1039/p29790000628

Cited by 4 publications

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“…Unambiguous evidence concerning the structures of o-complexes has been obtained by nmr spectroscopy for a variety of structural types (15)(16)(17)(18)(19)(20)(21)(22)(23). However, the nmr method has been found unworkable in the present system.…”

Section: Resultsmentioning

confidence: 87%

1,3-Dinitrobenzene – hydroxide ion interactions. Equilibrium constants for σ-complex formation in the dimethylformamide–water solvent system

Buncel¹,

Zabel²

1981

Can. J. Chem.

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ERWIN BUNCEL and ALLEN W. ZABEL. Can. J . Chem. 59, 3168 (1981). The results of a uv-visible spectroscopic study of the interaction of 1,3-dinitrobenzene (DNB) with hydroxide ion in aqueous dimethylformamide (DMF) media are reported. Formation of several spectral species has been discerned, depending on factors such as the relative concentrations of the reactants, the time scale of the experiments, and the medium composition. The principal interaction is formation of the I-hydroxy-2,4-dinitrocyclohexadienate anion. The molar absorptivities of this o-complex, and the equilibrium constants (K,) for its formation, have been determined as a function of medium composition. Values of K, increase from 7.5 M

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Section: Resultsmentioning

confidence: 87%

1,3-Dinitrobenzene – hydroxide ion interactions. Equilibrium constants for σ-complex formation in the dimethylformamide–water solvent system

Buncel¹,

Zabel²

1981

Can. J. Chem.

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ChemInform Abstract: PROTON NUCLEAR MAGNETIC RESONANCE STUDIES OF THE PRODUCTS FORMED BY POLYNITROBENZENES WHEN DISSOLVED IN LIQUID AMMONIA

Chudek¹,

Foster²

1979

Chemischer Informationsdienst

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The Kinetics and Mechanisms of Aromatic Nucleophilic Substitution Reactions in Liquid Ammonia

Atherton

Page

2011

J. Org. Chem.

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The rates of aromatic nucleophilic substitution reactions in liquid ammonia are much faster than those in protic solvents indicating that liquid ammonia behaves like a typical dipolar aprotic solvent in its solvent effects on organic reactions. Nitrofluorobenzenes (NFBs) readily undergo solvolysis in liquid ammonia and 2-nitrofluorobenzene is about 30 times more reactive than the 4-substituted isomer. Oxygen nucleophiles, such as alkoxide and phenoxide ions, readily displace fluorine of 4-NFB in liquid ammonia to give the corresponding substitution product with little or no competing solvolysis product. Using the pK(a) of the substituted phenols in liquid ammonia, the Brønsted β(nuc) for the reaction of 4-NFB with para-substituted phenoxides is 0.91, indicative of the removal of most of the negative charge on the oxygen anion and complete bond formation in the transition state and therefore suggests that the decomposition of the Meisenheimer σ-intermediate is rate limiting. The aminolysis of 4-NFB occurs without general base catalysis by the amine and the second-order rate constants generate a Brønsted β(nuc) of 0.36 using either the pK(a) of aminium ion in acetonitrile or in water, which is also interpreted in terms of rate limiting breakdown of the Meisenheimer σ-intermediate. Nitrobenzene and diazene are formed as unusual products from the reaction between sodium azide and 4-NFB, which may be due to the initially formed 4-nitroazidobenzene decomposing to give a nitrene intermediate, which may then give diazene or be trapped by ammonia to give the unstable hydrazine which then yields nitrobenzene.

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Proton nuclear magnetic resonance studies of the products formed by polynitrobenzenes when dissolved in liquid ammonia

Cited by 4 publications

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1,3-Dinitrobenzene – hydroxide ion interactions. Equilibrium constants for σ-complex formation in the dimethylformamide–water solvent system

1,3-Dinitrobenzene – hydroxide ion interactions. Equilibrium constants for σ-complex formation in the dimethylformamide–water solvent system

ChemInform Abstract: PROTON NUCLEAR MAGNETIC RESONANCE STUDIES OF THE PRODUCTS FORMED BY POLYNITROBENZENES WHEN DISSOLVED IN LIQUID AMMONIA

The Kinetics and Mechanisms of Aromatic Nucleophilic Substitution Reactions in Liquid Ammonia

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