Atom-transfer reaction rates for thermal fluorine atoms with CH3X and CF3X (X = bromo, iodo)

Iyer, R. Subramonia; Rowland, F. S.

doi:10.1021/j150617a017

Cited by 18 publications

(12 citation statements)

References 11 publications

(18 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…All evidence in the spectrokinetic study of the products of the reaction of F atoms with CH 3 Br and CF 2 BrH points toward F + CH 2 BrO 2 f products (27) formation of F adducts with the parent species. The question is: What is the nature of these species?…”

Section: Discussionmentioning

confidence: 95%

“…The kinetics and mechanism of the reaction of F atoms with CH 3 Br have been studied previously by Iyer and Rowland, 26,27 Nielsen et al, 6 and Wallington et al 21 Iyer and Rowland were the first to study this reaction and reported that at 283 K in the presence of 3000 Torr of SF 6 diluent the reaction proceeds predominately via hydrogen atom abstraction with a small (0.27%) contribution by a direct displacement mechanism to give CH 3 F and Br. The rate constant for hydrogen abstraction reported by Iyer and Rowland was (6.1 ( 0.7) × 10 -11 cm 3 molecule -1 s -1 .…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Kinetics and Mechanism of the Reaction of F Atoms with CH₃Br

et al. 1996

View full text Add to dashboard Cite

The reaction of F atoms with CH 3 Br at 296 K was studied using a pulse radiolysis/transient UV absorption spectroscopy absolute technique and a FTIR relative rate technique. The rate constant for this reaction was determined to be (4.46 ( 0.22) × 10 -11 . The reaction proceeds via two channels, 69 ( 5%, via hydrogen abstraction giving CH 2 Br radicals and HF, and 31 ( 5%, to give the adduct CH 3 Br--F. In the FTIR system the observed rate constant was 69 ( 8% of that measured using the pulse radiolysis system because the CH 3 Br--F adduct falls apart to re-form the reactants. The CH 3 Br--F adduct reacts with NO, with a rate constant of (2.25 ( 0.14) × 10 -11 cm 3 molecule -1 s -1 , giving FNO as a product. There was no discernible reaction of the CH 3 Br--F adduct with O 2 and an upper limit of 6 × 10 -15 cm 3 molecule -1 s -1 was derived for this reaction. The CH 3 Br--F adduct absorbs strongly at 260-340 nm. The absorption cross section at 280 nm of the CH 3 Br--F adduct was (2.06 ( 0.31) × 10 -17 cm 2 molecule -1 . A lower limit for the equilibrium constant was [CH 3 Br--F]/([CH 3 Br][F]) > 5 × 10 -16 cm 3 molecule -1 at 296 K. A lower limit of 12 kcal mol -1 is estimated for the binding energy of the F atom in the CH 3 Br--F adduct. The UV absorption spectrum of the CH 2 BrO 2 radical was determined; at 250 nm σ ) (3.4 ( 0.9) × 10 -18 cm 2 molecule -1 .

show abstract

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Kinetics and Mechanism of the Reaction of F Atoms with CH₃Br

et al. 1996

View full text Add to dashboard Cite

show abstract

“…The mutual reaction of CF 3 was studied in a CF 3 H/F system at large excess of CF 3 H over F. While the alternative CF 3 I þ F reaction as CF 3 source benefits from a much higher rate coefficient (1.6 Â 10 À10 cm 3 s À1 ) 25 than the F þ CF 3 H reaction (1.5 Â 10 À13 cm 3 s À1 ), 26 the difference between the ionisation potential of CF 3 (9.3 eV) and the appearance potential of CF 3 1 from CF 3 I (10.9 eV) is so small 27 that CF 3 I cannot be used in systems where it has to be in excess to the co-reactant F, and its use is therefore restricted to the study of the CF 3 þ F reaction.…”

Section: Methodology (A) Determination Of [F]mentioning

confidence: 99%

The kinetics of the CF₃+ CF₃and CF₃+ F combination reactions at 290 K and at He-pressures of ≈1–6 Torr

Dils

Vertommen

Carl

et al. 2005

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The rate constants for the combination reactions CF3 + CF3 and CF3 + F at 290 K and helium pressures of approximately 1-6 Torr have been determined, using clean chemical sources of CF3, by means of discharge flow-molecular beam sampling-threshold ionisation mass spectrometry (DF/MB-TIMS). For the mutual reaction of CF3, no pressure dependence could be observed over the 1-6 Torr pressure range, indicating that the obtained rate constant of k1 infinity = (1.8 +/- 0.6) x 10(-12) cm3 s-1 is the high pressure limit. This result, which agrees with the lowest values in literature but is ca. five times smaller than the most recent data, is fully in line with the known trend in the mutual reaction rate constant for the series CH3; CH2F; and CHF2. The reaction of CF3 with F was found to exhibit a clear pressure dependence in the 0.5 to 6 Torr range. Using a Troe fall-off formalism, the low-pressure limit rate constant was determined as k20(He) = (1.47 +/- 0.24) x 10(-28) cm6 S(-1), differing substantially from the only available previous determination; a variational transition state theoretical treatment is shown to support our data.

show abstract

“…(2) AH =-36 kcal/mol (3) AH =-10 kcal/mol (4) F + CH 3I~H F + CH 3I F + CH 3I~I F + CH 3 This reaction and its deuterated version are carried out between neutral reactants in the gas phase. Using singlecollision conditions, one can (a) prove the inversion mechanism even with an optically-inactive molecule, (b) measure the rate constant, and (c) measure the kinetic energy release of the product.…”

Section: F+ Ch 3imentioning

confidence: 99%

Dynamics of the Inversion Reaction

Bersohn

Kawasaki

1994

Israel Journal of Chemistry

View full text Add to dashboard Cite

Three examples are presented of homolytic bimolecular substitutions, F + CH3I, H + CD4, and H + SiD4. All are shown by laser techniques to proceed by inversion. For the latter two reactions, the proof is based on the demonstration that the entering H atom and the leaving D atom have approximately parallel velocities. The isotopic substitution reactions are almost vibrationally adiabatic in the sense that the departing D atom carries away about 80% of the kinetic energy of the incoming H atom.

show abstract

Atom-transfer reaction rates for thermal fluorine atoms with CH3X and CF3X (X = bromo, iodo)

Cited by 18 publications

References 11 publications

Kinetics and Mechanism of the Reaction of F Atoms with CH₃Br

Kinetics and Mechanism of the Reaction of F Atoms with CH₃Br

The kinetics of the CF₃+ CF₃and CF₃+ F combination reactions at 290 K and at He-pressures of ≈1–6 Torr

Dynamics of the Inversion Reaction

Contact Info

Product

Resources

About

Atom-transfer reaction rates for thermal fluorine atoms with CH3X and CF3X (X = bromo, iodo)

Cited by 18 publications

References 11 publications

Kinetics and Mechanism of the Reaction of F Atoms with CH3Br

Kinetics and Mechanism of the Reaction of F Atoms with CH3Br

The kinetics of the CF3+ CF3and CF3+ F combination reactions at 290 K and at He-pressures of ≈1–6 Torr

Dynamics of the Inversion Reaction

Contact Info

Product

Resources

About

Kinetics and Mechanism of the Reaction of F Atoms with CH₃Br

Kinetics and Mechanism of the Reaction of F Atoms with CH₃Br

The kinetics of the CF₃+ CF₃and CF₃+ F combination reactions at 290 K and at He-pressures of ≈1–6 Torr