Mechanism of the thermal and photochemical decomposition of azoalkanes

Engel, Paul S.

doi:10.1021/cr60324a001

Cited by 457 publications

(225 citation statements)

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“…90 Experimentally, the absorption maximum is estimated to be ∼3.6 eV. 84 Quantitative agreement between the SFDFT/EFP and full SFDFT is also observed for the absorption energy of cis-azomethane, 3.61 (3.61) eV.…”

Section: A Azomethane-water Clustermentioning

confidence: 79%

“…Since azomethane is the simplest molecule in the azo family, both experiments and theoretical calculations have been reported. [84][85][86][87][88][89][90] Before describing the CI points of hydrated azomethane, consider the accuracy of the present implementation of SFDFT/EFP1 analytic energy gradients. The analytic gradient was calculated for the azomethane · 2(H 2 O) cluster.…”

Section: A Azomethane-water Clustermentioning

confidence: 99%

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Optimizing conical intersections of solvated molecules: The combined spin-flip density functional theory/effective fragment potential method

Minezawa

Gordon

2012

The Journal of Chemical Physics

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Solvent effects on a potential energy surface crossing are investigated by optimizing a conical intersection (CI) in solution. To this end, the analytic energy gradient has been derived and implemented for the collinear spinflip density functional theory (SFDFT) combined with the effective fragment potential (EFP) solvent model. The new method is applied to the azomethane-water cluster and the chromophore of green fluorescent protein in aqueous solution. These applications illustrate not only dramatic changes in the CI geometries but also strong stabilization of the CI in a polar solvent. Furthermore, the CI geometries obtained by the hybrid SFDFT/EFP scheme reproduce those by the full SFDFT, indicating that the SFDFT/EFP method is an efficient and promising approach for understanding nonadiabatic processes in solution. Solvent effects on a potential energy surface crossing are investigated by optimizing a conical intersection (CI) in solution. To this end, the analytic energy gradient has been derived and implemented for the collinear spin-flip density functional theory (SFDFT) combined with the effective fragment potential (EFP) solvent model. The new method is applied to the azomethane-water cluster and the chromophore of green fluorescent protein in aqueous solution. These applications illustrate not only dramatic changes in the CI geometries but also strong stabilization of the CI in a polar solvent. Furthermore, the CI geometries obtained by the hybrid SFDFT/EFP scheme reproduce those by the full SFDFT, indicating that the SFDFT/EFP method is an efficient and promising approach for understanding nonadiabatic processes in solution.

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Section: A Azomethane-water Clustermentioning

confidence: 79%

Section: A Azomethane-water Clustermentioning

confidence: 99%

Optimizing conical intersections of solvated molecules: The combined spin-flip density functional theory/effective fragment potential method

Minezawa

Gordon

2012

The Journal of Chemical Physics

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“…Evaporating the solvent in the dark at O°C/ 18 Torr afforded a yellow oil which was distilled at 42OCIO. 1 Torr to yield 0.20 g (9 1 %) of a slight yellow oil. The infrared and 'H-nmr (90 MHz) data were in agreement with published data (8).…”

Section: Methodsmentioning

confidence: 99%

“…The importance of azoalkanes in the mechanistic studies of radicals and diradicals (1) and in synthetic applications (2) has been amply demonstrated over a number of decades. Through these studies, however, a group of azoalkanes, namely the structure types shown, have become recognized to be reluctant in eliminating molecular nitrogen on thermal as well as photochemical activation.…”

mentioning

confidence: 99%

Photoreluctant azoalkanes: 185-nm photolysis of E- and Z-diazacyclooct-2-ene

Adam¹,

Oppenländer²

1985

Can. J. Chem.

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The l85-nm photolyses off E- and Z-1,2-diazacyclooct-1-enes (1) result mainly in denitrogenation, affording 1-hexene and cyclohexane in a 2:1 ratio. In comparison to the direct 350-nm photolyses the denitrogenation efficiencies are enhanced by 42- and 26-fold for the E- and Z-isomers, respectively. It is proposed that the photoisomerization (350 nm) takes place from the S1(n−,π*)-state and the photodenitrogenation (185 nm) out of the S2-state.

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“…(4). One kind has a low activation energy for isomerization, relative to decomposition, and the other, a high activation energy for isomerization relative to decomposition.…”

Section: Rate Of Decotrlj>ositio~z Ofthe Trvo Isomersmentioning

confidence: 99%

The thermal decomposition of azobenzene

Barton¹,

Hodgett²,

Skirving³

et al. 1983

Can. J. Chem.

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The rate of nitrogen formation during the thermal decomposition of azobenzene in static and stirred-flow systems was measured over the temperature range of 368.9 °C to 437.4 °C. The first order rate constant was found to be given by the expression[Formula: see text]A consideration of the equilibrium constant between cis-azobenzene and trans-azobenzenc, and the rate of attainment of equilibrium, leads to the conclusion that a small concentration of cis-azobenzene is always present, at equilibrium with the trans isomer. Since the cis isomer is likely to be more reactive than the trans isomer the rate constant cannot be ascribed to the trans isomer alone. No effect of variation of surface-to-volume ratio could be detected. Some preliminary experiments in which toluene and ethylene were employed as additives indicated that these did not affect the rate of formation of nitrogen. Nevertheless, because of a certain amount of scatter in the results, a small effect could not be excluded. There were at least nine products, in addition to nitrogen.

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Mechanism of the thermal and photochemical decomposition of azoalkanes

Cited by 457 publications

References 0 publications

Optimizing conical intersections of solvated molecules: The combined spin-flip density functional theory/effective fragment potential method

Optimizing conical intersections of solvated molecules: The combined spin-flip density functional theory/effective fragment potential method

Photoreluctant azoalkanes: 185-nm photolysis of E- and Z-diazacyclooct-2-ene

The thermal decomposition of azobenzene

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