Chemiluminescence studies on the oxidative decomposition of 2,2'-azobis(2-methylpropanenitrile)

Vasvári, Gábor; Kuramshin, E. M.; Holly, S.; Vidóczy, Tamás; Gál, D.

doi:10.1021/j100324a026

Cited by 12 publications

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“…For modeling the kinetics of the oxidation process and chemiluminescence emission, COPASI software package (27), a facile successor to the previously developed GEPASI sofware (28)(29)(30), was applied. The input data of rate constants k 2 -k 16 (k 2 = 5x10 8 M À1 s À1 , k 3 = 1 M À1 s À1 , k 4 = 20 M À1 s À1 , k 5 = 5 9 10 8 M À1 s À1 , k 6 = 7 M À1 s À1 , k 7 = 10 8 M À1 s À1 , k 8 = 10 8 M À1 s À1 , k 9 = 10 8 M À1 s À1 , k 10 = 10 8 M À1 s À1 , k 11 = 10 6 M À1 s À1 , k 12 = 10 8 M À1 s À1 , k 13 = 2.8 9 10 6 M À1 s À1 , k 14 = 1.5 9 10 8 M À1 s À1 , k 15 = 10 8 M À1 s À1 , k 16 = 2.8 9 10 8 M À1 s À1 ) of elementary stages 2-16 of the oxidation mechanism (Scheme 3) constituted the mean values of the corresponding rate constants available in the literature for akin hydrocarbons (23,(31)(32)(33)(34)(35). The initiation rate (i.e.…”

Section: Methodsmentioning

confidence: 99%

“…Eq. ) upon rapid admission of oxygen into the reaction cell containing the solution of hydrocarbon being oxidized and the pertinent initiator of the free‐radical oxidation process . Before admission of oxygen into the reaction mixture, the chain reaction according to Scheme does not generate any chemiluminescence.…”

Section: Kinetic Background and Analysismentioning

confidence: 99%

“…Therefore, keeping track of the reaction course may be performed by monitoring the chemiluminescence kinetics in either of these two emission bands. However, since recording the chemiluminescence in visible region is more convenient, it is customary to measure the light emission derived from the excited carbonyl species without detection of light emitted by singlet oxygen . To enhance the total intensity of light, the appropriate luminophores may be added to a chemiluminescent “cocktail.” In such a case, the electronic energy transfer (as a rule, triplet–triplet or triplet–singlet) from primary excited carbonyl species (with low phosphorescence yield) to the particular luminophoric enhancer (with high luminescence quantum yield) intervene into the overall chemiluminescence process, and the sensitized light emission of the added enhancer contributes greatly to the total light intensity.…”

Section: Introductionmentioning

confidence: 99%

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Updating the Chemiluminescence Oxygen‐Aftereffect Method for Determining the Rate Constant of the Peroxy‐Radical Self‐Reaction: Oxidation of Cyclohexene

Fedorova

Lapina

Menshov

et al. 2018

Photochem & Photobiology

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Updating the facile chemiluminescence oxygen‐aftereffect method, most suitable for determining the rate constant (kt) of the peroxy‐radical self‐reaction (main chemiluminescence channel), pertained to considering the sensitivity of such a method toward a disturbing influence of the peroxy radicals of the initiator of the chain oxidation process. Such a disturbance may derive from the side chemiluminescent reaction, which involves peroxy radicals of both hydrocarbon and initiator. To examine the applicability and limitations of the chemiluminescence method under present scrutiny, cyclohexene was used as the model oxidizable hydrocarbon substrate. Computer simulations of the reaction and chemiluminescence kinetics have demonstrated the validity of the considered methodology at the value of the rate constant of the propagation of the overall chain process by peroxy radicals of the initiator higher than 1 m−1 s−1. Despite that the chemiluminescence time profile and the stationary level of the total chemiluminescence intensity depend on the kinetics of the side chemiluminescence channel and on the ratio of the excited‐state generation yields in the mentioned reaction channel and in the main chemiluminescence process, the value of kt assessed by the oxygen‐aftereffect method has been found independent of variation of these characteristics.

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Section: Methodsmentioning

confidence: 99%

Section: Kinetic Background and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Updating the Chemiluminescence Oxygen‐Aftereffect Method for Determining the Rate Constant of the Peroxy‐Radical Self‐Reaction: Oxidation of Cyclohexene

Fedorova

Lapina

Menshov

et al. 2018

Photochem & Photobiology

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“…Reactions (16,19,20) are responsible partly for the surplus consumption of DMA and POOP since the latter oxidizes leuco-dyes to the corresponding dye-salts:…”

Section: Ah = 598mentioning

confidence: 99%

The origin and nature of chemiluminescence in the dibenzoylperoxide‐dimethylaniline reaction

Vasvári

Hofmann

1998

Ber Bunsenges Phys Chem

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It has been established that the dibenzoylperoxide (POOP)+dimethylaniline (DMA) reaction is suitable to the slow production of free radicals at ambient temperature and in the absence of oxygen. The process is accompanied by a well measurable chemiluminescence (CL) without added sensitizer. The reaction carried out in acetonitrile is mainly ionic with the formation of radicals in between. We assume the existence of a 2:1 DMA/POOP complex as a possible source of radicals. The kinetics of CL is determined by the formation and decomposition rate of this complex. Calculated rate constant values: k(f) = 3 × 10−3 M−1 s−1 and k(d) = 1 × 10−3 s−1. Based on the spectrum of the CL light and taking into consideration the analytical results we assume that the energy of CL is delivered almost totally by the cage termination product (ΔH(r) =‐385 kJ/mol) formed in excited state and this energy is transferred to the triphenylmethane dye‐salt products (Malachite Green, Crystal Violet) which are the probable emitters of the CL light. Hydroperoxide is not formed in the reaction.

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Self‐Reaction of Benzylperoxy Radicals in the Oxidation of Toluene. A Chemiluminescence and Product Study

Vasvári

Gál

1993

Ber Bunsenges Phys Chem

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Chemical Kinetics I Energy Transfer I Light, Emission I Luminescence I RadicalsThe CL study of the oxidation of toluene initiated by AIBN has shown that both triplet and singlet benzaldehyde is formed (T/S i= 10.5). The lifetimes in toluene are: T~ = 4 . s and rT = 1.9 . lO-'s.-In the presence of DPA the kinetic curve of the CL light shows a maximum at [DPA] > M. The CL spectrum of the oxidation of toluene lacks both the fluorescence and phosphorescence peaks of the excited benzaldehyde (due to the very low efficiency of photon emission and very strong quenching by O2 and toluene). -Analysis of product distribution by HPLC revealed the formation of benzaldehyde, benzylalcohol, benzylhydroperoxide and benzoic acid. A small amount of H202 was also detected by spectrophotometry. Since the ratio of aldehyde/alcohol is always higher than unity detailed study of all circumstances led us to the conclusion that benzylperoxy radicals terminate both by the Russell-mechanism and by the transition state containing two five-membered rings suggested by Bennett and Summers.-The activation energy of hydrogen abstraction from toluene by benzylperoxy radicals is 53 kJlmol and the rate constant of this reaction does not differ essentially from the same reaction of ethylbenzene. The kinetic chain length of oxidation calculated from the analytical data is equal to 2k0.2 (75-90°C). IntroductionIn our previous paper [l] which dealt with the detailed chemiluminescence study of the oxidative decomposition of 2,2'-azo-bis-2-methylpropanenitrile (AIBN) we expressed our aim to investigate the origin of the very weak chemiluminescence (CL) observed in the liquid phase oxidation for primary-, secondary-and tertiary aralkyl hydrocarbons.Peroxy radicals formed during the oxidation of AIBN are tertiary ones. The kinetics and mechanism of the liquid phase oxidation of secondary hydrocarbons (including the study of the CL light, as well) is well known [2,3] and served as a basis for the elaboration of the CL method [4] following the termination of peroxy radicals.So we deemed it advisable to study the combination of primary peroxy radicals by the CL method neglected so far from different reasons.In the present paper we report the results of our CL and product studies carried out with benzylperoxy radicals obtained from the AIBN initiated oxidation of toluene.

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Chemiluminescence studies on the oxidative decomposition of 2,2'-azobis(2-methylpropanenitrile)

Cited by 12 publications

References 1 publication

Updating the Chemiluminescence Oxygen‐Aftereffect Method for Determining the Rate Constant of the Peroxy‐Radical Self‐Reaction: Oxidation of Cyclohexene

Updating the Chemiluminescence Oxygen‐Aftereffect Method for Determining the Rate Constant of the Peroxy‐Radical Self‐Reaction: Oxidation of Cyclohexene

The origin and nature of chemiluminescence in the dibenzoylperoxide‐dimethylaniline reaction

Self‐Reaction of Benzylperoxy Radicals in the Oxidation of Toluene. A Chemiluminescence and Product Study

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