Lifetime of acyloxy radicals produced by decomposition of acetylpropionyl peroxide

Скаковский, Е. Д.; Lamotkin, S. A.; Tychinskaya, L. Yu.

doi:10.1007/bf02675091

Cited by 9 publications

(8 citation statements)

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“…The approximate enthalpies of reactions used in Section 3 were calculated from the enthalpies of formation of gas phase molecules, radicals, and cations found in the literature. [13][14][15][16][17][18] All values refer to gas phase species at standard temperature (298 K) and can therefore serve only as a rough guide of the enthalpy balance in the molecular aggregates we are interested in. Their pre-ionization temperature is not known (presumably o200 K for all conditions (neat, seeded in He)), but we expect the average thermal energy per degree of freedom to be insignificant relative to the energy balance of the processes taking place after ionization.…”

Section: Computationmentioning

confidence: 99%

“…The first step of the cycle (eqn (6a)) is barrierless (see Table 1) and therefore very fast, as has been observed for acyloxy radicals in general. [14][15][16] For the second step, we calculate a barrier of about 39 kJ mol À1 , which is easily overcome by the available energy. The fragmentation of HAc into carbon…”

Section: Single Photon Vuv Ionization Versus Na-dopingmentioning

confidence: 99%

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Sodium-doping as a reference to study the influence of intracluster chemistry on the fragmentation of weakly-bound clusters upon vacuum ultraviolet photoionization

Litman

Yoder

Schläppi

et al. 2013

Phys. Chem. Chem. Phys.

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The fragmentation of methanol, water, dimethyl ether, and acetic acid clusters upon photoionization with a single vacuum ultraviolet (VUV) photon of 10.1 eV, 13.3 eV, or 17.5 eV energy is studied with mass spectrometry. The sodium-doping method is used as an independent approximate measure of the original cluster size distribution providing information on the degree of fragmentation upon VUV ionization. The experimental results show strong fragmentation for (CH(3))(2)O and CH(3)CO(2)H clusters but minor fragmentation for H(2)O and CH(3)OH clusters. The pronounced cluster decay for (CH(3))(2)O and CH(3)CO(2)H is explained by additional intracluster chain reactions that occur after the initial fast proton transfer in the ionic clusters, i.e. the decay of (CH(3))(2)O molecules into H(2), CO, and CH(4) catalyzed by the methoxymethyl radical, and the decay of CH(3)CO(2)H molecules into CO(2) and CH(4) catalyzed by the acetyloxy radical. The absence of equivalent reaction cycles in ionic H(2)O and CH(3)OH clusters after the fast proton transfer is consistent with the much less pronounced cluster fragmentation observed upon VUV ionization. The study shows that VUV photoionization even at threshold cannot in general be considered a soft ionization method for weakly-bound clusters, largely because of potential intracluster reaction.

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Section: Computationmentioning

confidence: 99%

Section: Single Photon Vuv Ionization Versus Na-dopingmentioning

confidence: 99%

Sodium-doping as a reference to study the influence of intracluster chemistry on the fragmentation of weakly-bound clusters upon vacuum ultraviolet photoionization

Litman

Yoder

Schläppi

et al. 2013

Phys. Chem. Chem. Phys.

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“…They are involved in almost every reactions in fuel systems, and in the earth's atmosphere. In particular, reactions of the free acyloxyl radical RCOO has attracted much attention from both theoretical and experimental chemists [4][5][6][7][8][9][10][11][12][13][14]. These radicals are readily formed from thermal decompositions and photo-decompositions of diacyl peroxides due to the weakness of -O-Obonds.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on the Reaction Mechanism of Co2 Formation From Acyloxy Radicals

Huệ¹

2018

JST

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The decomposition mechanism of acyloxy radicals has been studied by the Density Functional Theory (DFT) using B3LYP functional in conjunction with the 6-311++G(d,p) and 6-311++G(3df,2p) basis sets. The potential energy profiles for reaction systems were generally established. Calculated results indicate that the formation of products including hydrocarbon radicals and CO 2 molecule is energetically favored. The rate of decomposition increases with the number of carbon in non-cyclic saturated acyloxy radicals. Calculated enthalpies and Gibbs free energies of reactions well agree with experimental values. This study is a contribution to the understanding of the reaction mechanism of decomposition of acyloxy radicals in atmosphere and combustion chemistry.

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“…Otherwise, the CIDNP of ethane could disappear due to spin-lattice relaxation in the methyl radicals. So in thermolysis of acetyl benzoyl peroxide (ABP), due to the short lifetime of the acetyloxyl radicals (10 -10 to 10 -9 s [6]), even in high magnetic fields we observe CIDNP in the protons of the products. Figure 2 shows the NMR spectra of the decomposition products of deaerated solutions of benzoyl peroxide (BP) in response to temperature (2 h at 343 K) and microwave radiation (3 minutes).…”

mentioning

confidence: 97%

NMR analysis of diacyl peroxide decomposition in methanol in response to temperature and microwave radiation

et al. 2012

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We have studied the decomposition of benzoyl and acetyl benzoyl peroxides in methanol-d 4 in response to temperature and microwave radiation. We have shown that chemically-induced dynamic nuclear polarization (CIDNP) can be observed even when the reactions are carried out in spectrometers with high magnetic fields. In this case, spin correlation persists in geminal radical pairs involving labile acyloxyl radicals. Regardless of the method used to initiate peroxide decomposition, the same amount of products are formed. Homolysis occurs according to a chain mechanism. The contribution of induced decomposition decreases over the course of the reaction. Dissolved oxygen molecules efficiently terminate the chain, decreasing the rate of peroxide decomposition. In the case of acetyl benzoyl peroxide, the product yield depends on the initiation mechanism: for microwave irradiation, the solvent molecules are more active while dissolved oxygen is less active than in thermolysis.

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Lifetime of acyloxy radicals produced by decomposition of acetylpropionyl peroxide

Cited by 9 publications

References 0 publications

Sodium-doping as a reference to study the influence of intracluster chemistry on the fragmentation of weakly-bound clusters upon vacuum ultraviolet photoionization

Sodium-doping as a reference to study the influence of intracluster chemistry on the fragmentation of weakly-bound clusters upon vacuum ultraviolet photoionization

Theoretical Study on the Reaction Mechanism of Co2 Formation From Acyloxy Radicals

NMR analysis of diacyl peroxide decomposition in methanol in response to temperature and microwave radiation

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