Reactions of trifluoromethyl radicals in the photolysis of hexafluoroacetone and hexafluoroazomethane

Chong, Shuang‐Ling; Toby, Sidney

doi:10.1021/j100708a013

Cited by 9 publications

(7 citation statements)

References 3 publications

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“…All these observations discussed above confirm clearly that the reaction mechanism is shown by eq 1-8. In addition, we suggest that our results support the minor occurrence of conditions the radical-combination reaction, (8), is very rapid, the rate-determining step for the formation of perfluorotrimethylhydroxylamine is (7). The specific reaction rate of (7) may be evaluated by kinetic analysis of the photolyzing mixture at reaction times after the maximum in [CF3NO]; that is, after essentially complete depletion of nitric oxide, provided it may be assumed that the produced perfluorotrimethylhydroxylamine does not contribute a mass peak at m/e 30 and provided we may take [NO] = 0.…”

Section: Methodssupporting

confidence: 67%

“…In addition, we suggest that our results support the minor occurrence of conditions the radical-combination reaction, (8), is very rapid, the rate-determining step for the formation of perfluorotrimethylhydroxylamine is (7). In addition, we suggest that our results support the minor occurrence of conditions the radical-combination reaction, (8), is very rapid, the rate-determining step for the formation of perfluorotrimethylhydroxylamine is (7).…”

Section: I1supporting

confidence: 65%

“…The intensity at m/e 99 (CF3NO+) is, however, too weak at this low concentration of nitric oxide for use in quantitative calculations. Hence, as shown in Figure 5, the maximum in [CF3NO] and subsequent decrease of [CF3NO] due to formation of perfluorotrimethylhydroxylamine via (7) and (8) and to leakage into the mass spectrometer are manifested (for 75-eV ionizing energy) by the maximum and subsequent decrease in the intensity of m/e 30 (NO+).…”

Section: Methodsmentioning

confidence: 96%

“…fluoronitrosomethane, a stable blue gas that can be isolated.19•20 The scavenging reaction, (6), is very efficient, the rate constant having been shown21 to be at least [10][11][12][13] cm3 molecule-1 sec-1, and it will, therefore, be the essentially exclusive fate of trifluoromethyl radicals until the nitric oxide concentration has been reduced to very low levels. Trifluoronitrosomethane, the product of (6), will also scavenge trifluoromethyl radicals by successive addition of the radicals to form perfluorotrimethylhydroxylamine,22"26 as shown by (7) and (8). Indeed, the photolysis of…”

Section: Dcnmentioning

confidence: 99%

“…Since its discovery and isolation by Blackley and Reinhard,30 the nitroxide radical produced in (7) has been well studied.25331-35 It abstracts hydrogen atoms from al-kane@ and adds to 0lefins3~~33 in a reaction predominating over hydrogen atom abstraction33 from olefins. It reacts very rapidly with free radicals, as would be expected, since it is itself a free radical.…”

mentioning

confidence: 99%

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Mass-spectrometric study of the reaction of trifluoromethyl radicals with nitric oxide

Tan¹,

Lampe²

1973

J. Phys. Chem.

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1335were the dominant mechanism.23 This prediction is related to the observation reported in the single-pulse shock tube study of the Hz + Dz exchange that the rate depended more strongly on the concentration of Dz than on H2.21,24 In the temperature range 1050-1200"K, the rate of Dz with CzNz was found to be faster than that of HZ with CzN2 although the rate decreased with increasing tempera t~r e .~~ According to VEC, the important species is CzNz" and not H2U or D2U. Consequently, there should be a decrease in the rate constant as expected from the normal isotope effect when D:l rather than Hz is reacting with CzN2. The magnitude of the isotope effect, A D J A H~, calculated from collision theory, is listed below for both atomic and VEC mechanisms. H,, D, + CN -HCN, DCN + H, D 0.73 (15) H, D + C2N2-HCN, DCN + CN 0.715 (16) Darryl Olivier who helped maintain the equipment, and Professors Robert Flurry and Peter Politzer for fruitful discussions. We appreciate very much a critical review of the manuscript by Professor S. H. Bauer. Publication costs assisted by The U. S. Atomic Energy Commission and The Petroleum Research FundThe photolysis of hexafluoroazomethane in the visible fluoromethyl radicals at near room temperature. The products of the photolysis are nitrogen, hexafluoroethane, perfluorotetramethylhydrazine, and perfluorohexamethyl-and near-ultraviolet regions of the spectrum has been well studiedz-? and often used8-12 as a convenient source of tri-

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Section: Methodssupporting

confidence: 67%

Section: I1supporting

confidence: 65%

Section: Methodsmentioning

confidence: 96%

Section: Dcnmentioning

confidence: 99%

mentioning

confidence: 99%

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Mass-spectrometric study of the reaction of trifluoromethyl radicals with nitric oxide

Tan¹,

Lampe²

1973

J. Phys. Chem.

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ChemInform Abstract: RK. VON TRIFLUORMETHYL‐RADIKALEN BEI DER PHOTOLYSE VON HEXAFLUORACETON UND HEXAFLUORAZOMETHAN (MECHANISMUS)

Chong¹,

Toby²

1970

Chemischer Informationsdienst. Organische Chemie

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Photolysis of 1,1,1‐trifluoromethylazomethane as a source of methyl and trifluoromethyl radicals

Craig

Setser

1974

Int J of Chemical Kinetics

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The photochemistry of 1 ,l , 1-trifluoromethylazomethane has been partially characterized. The quantum yield for Nz formation from photolysis at 366 nm and room temperature was unity at low pressure and decreased to 0.5 at 630 torr. At room temperature the principal products were C2H6, C2F6, CH3CF3 (or CHzCFz + HF at reduced pressures), plus substituted hydrazines, which mainly arise from addition of CF3 to the parent followed by combination of these radicals with CH3 or CF3. These fluorinated methyl hydrazine products detract from the general utility of CFa-N2-R compounds as sources for simultaneous study of the chemistry of CF3 and R radicals. At room temperature the hydrazine products accounted for more than 50% of the total yield; however, these products can be reduced by lowering the temperature and at 195°K their yields are negligible. The quantum yield for intramolecular (direct) formation of CH3CF3 + NZ was shown to be <0.002.

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Reactions of trifluoromethyl radicals in the photolysis of hexafluoroacetone and hexafluoroazomethane

Cited by 9 publications

References 3 publications

Mass-spectrometric study of the reaction of trifluoromethyl radicals with nitric oxide

Mass-spectrometric study of the reaction of trifluoromethyl radicals with nitric oxide

ChemInform Abstract: RK. VON TRIFLUORMETHYL‐RADIKALEN BEI DER PHOTOLYSE VON HEXAFLUORACETON UND HEXAFLUORAZOMETHAN (MECHANISMUS)

Photolysis of 1,1,1‐trifluoromethylazomethane as a source of methyl and trifluoromethyl radicals

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