Low-Pressure Study of the Reaction of Cl Atoms with Isoprene

Bedjanian, Yuri; Laverdet, G.; Bras, G. Le

doi:10.1021/jp973336c

Cited by 81 publications

(113 citation statements)

References 16 publications

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“…The reaction probability of C1 with alkane and alkene surfaces is close to the gas-kinetic limit, analogous to its gas-phase reactions [Bedjanian et al, 1998]. In contrast, the uptake of Br by an alkane surface (ff •10 -2) is higher than expected in analogy to its gas-phase reactions (Table 2) For the closely packed monolayers the high-pressure limit can be reached at the low pressures of our experiments.…”

Section: Discussionsupporting

confidence: 62%

Uptake of Cl and Br by organic surfaces—A perspective on organic aerosols processing by tropospheric oxidants

Moise

Rudich

2001

Geophysical Research Letters

122

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Abstract.The reactive uptake of C1 and Br atoms by closely packed organic thin films was studied in a flow reactor. For C1, the reactive uptake coefficient, 'y, was near collision rate for alkane and alkene surfaces. For Br, -y =(34-1) x 10 -2 for alkane and 7=(54-2) x 10 -2 for alkene surfaces. The processing of the surface was monitored using FTIR, XPS and contact angle measurements. Oxidized surface-bound products and a concurrent increase in hydrophilicity were observed. The probability of a reactive collision between Br, C1, O(3P), O3 and NOs and surfacebound organics is compared with that of comparable gasphase reactions, showing that reactions with a high activation energy in the gas-phase have an enhanced surface reaction probability. The uptake coefficients for these tropospheric oxidants are used to estimate the processing time for an organic coated aerosol.

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Section: Discussionsupporting

confidence: 62%

Uptake of Cl and Br by organic surfaces—A perspective on organic aerosols processing by tropospheric oxidants

Moise

Rudich

2001

Geophysical Research Letters

122

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“…The kinetics of the chlorine atom reactions under various conditions of temperature and pressure with simple alkenes such as ethene, propene, 1-butene, trans-2-butene, and 1-pentene 17,21,22, and with some dienes [50][51][52][53][54][55][56][57][58][59][60] have been reported. The reaction proceeds primarily by reversible addition to the double bond; at sufficiently high pressures, the chlorine-alkene adduct is stabilized as a chlorinated alkyl radical, for example in the case of propene:…”

Section: à3mentioning

confidence: 99%

Kinetics of reactions of chlorine atoms with a series of alkenes at 1 atm and 298 K: structure and reactivity

Ezell

Wang

Ezell

et al. 2002

Phys. Chem. Chem. Phys.

117

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Chlorine atoms are important oxidants at dawn in the marine boundary layer where a variety of organics are also present, including alkenes. Using the relative rate technique, the kinetics of the gas phase reactions of atomic chlorine with a series of alkenes, relative to n-heptane as a reference, have been investigated at (298 AE 3) K and 1 atmosphere in either synthetic air or nitrogen. The rate constant for n-heptane, relative to n-butane whose rate constant was taken to be 2.18 Â 10 À10 cm 3 molecule À1 s À1, was also measured and found to be (3.97 AE 0.27) Â 10 À10 cm 3 molecule À1 s À1 (2s). Based on this value for the n-heptane reaction, the following absolute values for the rate constants, k (in units of 10 À10 cm 3 molecule À1 s À1) for the chlorine atom reactions were determined: propene, 2.64 AE 0.21; isobutene, 3.40 AE 0.28; 1-butene, 3.38 AE 0.48; cis-2-butene, 3.76 AE 0.84; trans-2-butene, 3.31 AE 0.47; 2-methyl-1-butene, 3.58 AE 0.40; 2-methyl-2-butene, 3.95 AE 0.32; 3-methyl-1-butene, 3.29 AE 0.36; 2-ethyl-1-butene, 3.89 AE 0.41; 1-pentene, 3.97 AE 0.36; 3-methyl-1-pentene, 3.85 AE 0.35; and cis-4-methyl-2-pentene, 4.11 AE 0.55 (AE2s). The errors reflect those in our relative rate measurements but do not include the 10% error in the absolute value of the n-butane rate constant upon which these rate constants are ultimately based. A structure-reactivity scheme is presented that assumes that rate constants for addition of chorine atoms to the double bond, as well as that for abstraction of an allylic hydrogen atom, depend upon the degree of alkyl substitution at the double bond and allylic carbons. The surprising result is that the allylic hydrogen atoms react less rapidly with chlorine atoms than the analogous alkyl hydrogens in alkanes. The atmospheric implications for loss of alkenes in the marine boundary layer are discussed.

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“…For example, negative activation energies have been noted for a wide variety of olefin reactions with Cl atoms, [1][2][3][4] with O( 3 P) atoms, [5][6][7][8][9] and with hydroxyl radicals. 10 The role of negative activation energies has also been widely discussed in the reactions of hydrocarbon radicals with hydrogen halides and the related reverse reactions.…”

Section: Introductionmentioning

confidence: 99%

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

et al. 2007

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A two transition state model is applied to the study of the addition of hydroxyl radical to ethylene. This reaction serves as a prototypical example of a radical-molecule reaction with a negative activation energy in the high-pressure limit. The model incorporates variational treatments of both inner and outer transition states. The outer transition state is treated with a recently derived long-range transition state theory approach focusing on the longest-ranged term in the potential. High-level quantum chemical estimates are incorporated in a variational transition state theory treatment of the inner transition state. Anharmonic effects in the inner transition state region are explored with direct phase space integration. A two-dimensional master equation is employed in treating the pressure dependence of the addition process. An accurate treatment of the two separate transition state regions at the energy and angular momentum resolved level is essential to the prediction of the temperature dependence of the addition rate. The transition from a dominant outer transition state to a dominant inner transition state is predicted to occur at about 130 K, with significant effects from both transition states over the 10 to 400 K temperature range. Modest adjustment in the ab initio predicted inner saddle point energy yields theoretical predictions which are in quantitative agreement with the available experimental observations. The theoretically predicted capture rate is reproduced to within 10% by the expression [4.93 × 10 -12 (T/298) -2.488 exp(-107.9/RT) + 3.33 × 10 -12 (T/298) 0.451 exp(117.6/RT); with R ) 1.987 and T in K] cm 3 molecules -1 s -1 over the 10-600 K range.

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Low-Pressure Study of the Reaction of Cl Atoms with Isoprene

Cited by 81 publications

References 16 publications

Uptake of Cl and Br by organic surfaces—A perspective on organic aerosols processing by tropospheric oxidants

Uptake of Cl and Br by organic surfaces—A perspective on organic aerosols processing by tropospheric oxidants

Kinetics of reactions of chlorine atoms with a series of alkenes at 1 atm and 298 K: structure and reactivity

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

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