The effect of reactant purity on the radiolysis of gaseous ethane and propane

Gawlowski, J.; Niedzielski, Jan; Herman, Jan A.

doi:10.1139/v77-068

Cited by 3 publications

(2 citation statements)

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“…1%) when the gas chromatograph was used at T = 50°C. All these analyses were routinely made on two gas-chromatographs (dual flame ionization detector) one equipped with a squalane column (4) and the other one with a UCON column maintained at room temperature (23DMB case) or at 50°C (33DMB case) (5).…”

Section: Methodsmentioning

confidence: 99%

The photolysis of 2,3- and 3,3-dimethyl-1-butene at 147.0 and 184.9 nm

Deslauriers¹,

Collin²

1985

Can. J. Chem.

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HELENE DESLAURIERS and GUY J. COLLINS. Can. J. Chem. 63, 62 (1985).The photofragmentation of 2,3-dimethylbutene and 3.3-dimethylbutene has been studied at 147 and 184.9 nm in the gas phase. The main primary decomposition process at both wavelengths involves the rupture of a P(C-C) bond. The quantum yield for this process is higher than 0.7 at 147 nm and is probably even higher at 184.9 nm. All dimethallyl radicals formed at 147 nm in this process decompose at low pressure, but some of them isomerize from the a , P -to the a,a-structure (and vice versa) -via a 1.4-H transfer -before decomposition. At 184.9 nm, the same primary process is used to get a rough value for the lifetime of the photoexcited molecule, compared with the one made with RRKM calculations by assuming that all the photon energy resides in the vibrational framework of the fundamental electronic state. These lifetimes are about one nanosecond or less.HELENE DESLAURIERS et GUY J. COLLINS. Can. J. Chem. 63, 62 (1985).On a CtudiC la photolyse des dimkthyl-2.3-et -3,3-butene-l a 147 et a 184,9 nm. Le principal mode de fragmentation de la molCcule photoexcitCe implique la rupture d'un lien C-C situC en position P.. Le rendement quantique de ce processus primaire est supCrieur a 0,7 a 147 nm et peut-Ctre plus ClevC encore a 184,9 nm. A 147 nm, tous les radicaux dimCthallyles se dkcomposent ii basse pression, mais certains le font aprks isomkrisation par transfert interne 1,4 d'un atome d'hydrogkne. A 184,9 nm le mCme processus primaire est utilisC pour determiner le temps de vie de la molCcule photoexcitke. Ce temps de vie, de I'ordre ou moins de la nanoseconde, est cornpark avec celui que I'on peut obtenir 21 I'aide de calculs RRKM en supposant que toute I'Cnergie du photon est distribuCe dans le tissu vibrationnel de la molCcule. IntroductionWe have recently studied the gaseous photolysis of tetramethylethylene and I-hexene at 184.9 nm. At low pressures (1 Tom = 1330 N m-2), both photoexcited molecules decompose. The photoexcited I-hexene molecule gives rise to the rupture of the P(C-C)bond (1) and that of the tetramethylethylene -a molecule without the P(C-C) bondgives rise to the rupture of either a P(C-H) or a a(C-C) bond (2) with similar probability. Moreover, at high pressure (above 100 Torr), isomers are formed with rather high quantum yields in the tetramethylethylene case: @(isomers) = 0.34 in the presence of high propane pressure (3). Conversely, the isomerization processes are very low or not even observed in the I-hexene case: @(isomers) 5 0.01 (1).This work has two main purposes. First, we shall examine in other C6 terminal olefins the validity of the rupture of the P(C-C) bond at low pressure, and, if possible, we shall estimate the lifetime of the photoexcited molecule. Second, we shall try to reconcile the apparent conflict observed above at high pressure: does the photoexcited molecule isomerize? We have chosen 2,3-dimethylbutene (23DMB) and 3,3-dimethylbutene (33DMB) for this study. It is hoped that any structural effect inside the C...

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Section: Methodsmentioning

confidence: 99%

The photolysis of 2,3- and 3,3-dimethyl-1-butene at 147.0 and 184.9 nm

Deslauriers¹,

Collin²

1985

Can. J. Chem.

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“…Thus, the radiolytic conversion of gaseous alkanes consists in a variety of processes resulting in predominant formation of higher molecular mass alkanes with branched structure. For example, the yields of hexane isomers formed via the steady-state irradiation of gaseous propane (p ¼ 0.1 MPa; T ¼ 308 K) are 0.17, 0.048, and 0.007 mmol/J for 2,3-dimethylbutane, 2-methylpentane, and nhexane, respectively (Gavlowski et al, 1977). The circulation mode ensures both dominating formation and saving of isoalkanes despite of considerable variations of composition of the feed gas and irradiation conditions (see Table 4).…”

Section: Fractional and Isomeric Compositions Of Liquid Productsmentioning

confidence: 99%