The Formation of Trifluoromethyl Radicals in the Gas Phase

Hodgins, J. W.; Haines, R. L.

doi:10.1139/v52-057

Cited by 27 publications

(10 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The observed experimental data for reactions (33), ( 37), (38) can sensibly be described by third-order kinetics within experimental error. 168-170 Calculations to allow for any marginal 'fall-off' to second-order kinetics for the relatively low pressure range with He ( < 0.15 atm) in atomic recombination measurements have been reported by Plane and co-workers 168-170 to include the observations of Luther et ~1 .…”

Section: ( C ) X + I + M -+ X I + Mmentioning

confidence: 56%

The tilden lecture. Fundamental collisional processes of alkali and alkaline earth atoms studied by spectroscopic methods

Husain¹

1989

J. Chem. Soc., Faraday Trans. 2

View full text Add to dashboard Cite

Recent developments for characterising absolute rate data for fundamental reactions of ground-state alkali-metal atoms by direct spectroscopic monitoring in the time-domain are presented against the historical background of diffusion flames. Time-resolved atomic resonance absorption and fluorescence spectroscopy, together with the use of atomic resonance fluorescence techniques in fast-flow systems have led to an extensive body of fundamental rate data that may be compared, in some instances, with measurements derived from molecular beams and some which are of particular relevance to flame chemistry and to the chemistry of alkali-metal atoms in the mesosphere. Emphasis is given to the kinetic study of the groups of the recombination processes between (i) Li, Na, K, Cs + O2 + M, (ii) Na, K, Rb, Cs + OH + M and (iii), K, Rb, C s + I + M with detailed consideration of the role of ionic surfaces and the dynamics on those surfaces. Whilst limited consideration is directed towards the study of oxidation reactions of ground state alkaline-earth-metal atoms in diffusion flames and in molecular beams, the kinetic study of electronically excited alkaline-earth-metal atoms which are optically metastable to varying degrees and where collisional removal may compete significantly with radiative loss is dealt with in detail. The general nature of kinetic data for electronically excited alkaline-earth-metal atoms in 3P, and D2 states derived from direct monitoring on low-pressure flames, discharge-flow systems, optical modulation methods and time-resolved emission following pulsed dye-laser excitation is presented. Detailed consideration is principally directed towards the study of diatomic oxidation products in specific vibronic states resulting from collisions between the electronically excited alkaline-earth-metal atoms and simple oxidants using the quantitative combination of time-resolved molecular and atomic emission, on the one hand, and both chemiluminescence and laser-induced fluorescence from molecular beams on the other. The kinetic study of product vibronic states, including the measurements of branching ratios, resulting from direct reaction and energy transfer is described. This quantitative, complementary combination of the time-domain and of the single-collision condition to investigate the details of such product states is emphasised as a major modern development in the study of atomic collisions in specific electronic states.? Delivered in London on Tuesday 3rd November, 1987.

show abstract

Section: ( C ) X + I + M -+ X I + Mmentioning

confidence: 56%

The tilden lecture. Fundamental collisional processes of alkali and alkaline earth atoms studied by spectroscopic methods

Husain¹

1989

J. Chem. Soc., Faraday Trans. 2

View full text Add to dashboard Cite

show abstract

“…as one proceeds down group VII. This trend is also seen in positive ion reactions (Morris et al 1992b-d) and in neutral-neutral reactions (Bradley et al 1976, Hodgins and Haines 1952, Le Bras and Combourieu 1978, Silver and De Haas 1981, Westenberg and De Haas 1977 where it can be explained simply by the decreasing C-X bond strength in the order CF3-C1> CF,-Br > CF,-I. For many of the negative ion reactions, however, there is evidence that the energetics and kinetics of electron transfer govern the reactivity by controlling the rate of electron transfer to the halocarbon in the initial phase of the reaction.…”

Section: Brf-cfbrmentioning

confidence: 71%

Reactivity of gas-phase anions with fully halogenated alkanes

Morris¹,

Viggiano²,

Paulson³

1996

International Reviews in Physical Chemistry

View full text Add to dashboard Cite

Gas-phase reactivity of negative ions with fully halogenated alkanes is reviewed, restricted to rate constant measurements under thermal conditions. Reactivity generally increases upon substitution by heavier halogens. Perfluorocarbons (PFCs) are generally unreactive with negative ions, but the highly reactive 0-anion reacts with the larger PFCs through multiple product channels. The trifluoromethyl halide series CF,X (X = C1, Br, I) has been well-studied, and the reactions tend to be fast when nondissociative electron transfer to the halocarbon would be exothermic, regardless of the actual resulting product channels. For many of the reactions of CF,X and other perhaloalkanes, reactivity correlates with both the electron affinities and the electron attachment rates of the perhaloalkanes, though notable exceptions exist. This and other evidence suggests that many of the reactions are initiated by electron transfer to the halocarbon, which tends to explain why the reactivity of CF,X generally increases in the order C1< Br < I for second-order reactions. The same reactivity trend in third-order association reactions is explained by the corresponding trends in CF,X dipole moment and polarizability. The results of several studies show that negative ion reactions are not a significant removal process for halocarbons in the atmosphere.

show abstract

“…While complete systematic studies of the bromofluoromethanes with atoms other than boron have not been performed (for a review of such studies, see ref 10-13), the available published data show that the reactive behavior of boron with the halomethanes is not unique. [14][15][16][17] This can be Seen in Table VII, which compares reaction cross sections of boron, sodium, and gallium with CIF3, CBrF3, CC1F3, and CF4. As can be seen in all these cases, the reactivity of CC1F3 is 2 Orders of magnitude smaller than the reactivity of CBrF3 (and CIF3 in the case of gallium and sodium).…”

Section: Discussionmentioning

confidence: 99%

Boron atom reactions with the bromomethanes

McKenzie¹,

Stanton²,

Tabacco³

et al. 1987

J. Phys. Chem.

View full text Add to dashboard Cite

Rate constants have been measured for the reactions of boron atoms with a series of bromomethanes and bromofluoromethanes. The experiments were performed in a linear flow apparatus at 300 K. The bimolecular rate constants were obtained by measuring the density of boron along the flow tube as a function of reactant gas density. The measured rate constants in units of cubic centimeters per molecule per second are for CBr4, 4.2 X 1CT11; for CBr3H, 8.1 X 1CT11; for CBr2H2, 1.3 X 10"10; for CBrH3, 5.7 X 10"11; for CBr3F, 3.8 X 10"11; for CBr2F2, 9.2 X 10"11; for CBrF3, 1.4 X 10"11; for CH3F, <8 X 10"14; and for CBr2Cl2, 1.4 X 10"10. These results are compared to the previously published work on the chlorofluoromethanes where the reactivity of the chlorine site was substantially reduced by fluorine substitution. The corresponding decrease in reactivity of the bromine site is not present in the bromofluoromethanes.

show abstract

The Formation of Trifluoromethyl Radicals in the Gas Phase

Cited by 27 publications

References 4 publications

The tilden lecture. Fundamental collisional processes of alkali and alkaline earth atoms studied by spectroscopic methods

The tilden lecture. Fundamental collisional processes of alkali and alkaline earth atoms studied by spectroscopic methods

Reactivity of gas-phase anions with fully halogenated alkanes

Boron atom reactions with the bromomethanes

Contact Info

Product

Resources

About