An Infrared Chemiluminescence Study of the Reactions of Hydrogen Atoms with CF3OCl and CF3O

Rengarajan, R.; Setser, D. W.; Desmarteau, D. D.

doi:10.1021/j100092a030

Cited by 18 publications

(25 citation statements)

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“…Formation of a triplet CF 2 O species has been postulated in the reaction of H + CF 3 O. 55 Due to the energy content of the reactants, fluorine abstraction by H could take place, in competition with a radical recombination giving CF 3 OH, either in the singlet or in the triplet state. On the triplet potential energy surface, F-abstraction can give rise to triplet CF 2 O.…”

Section: Resultsmentioning

confidence: 99%

Thermochemical Parameters of CHFO and CF₂O

2008

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Thermochemical properties of CHFO and CF 2O and their derivatives were calculated by using coupled-cluster theory (U)CCSD(T) calculations with the aug-cc-pV nZ ( n = D, T, Q, 5) basis sets extrapolated to the complete basis set limit with additional corrections. The predicted properties include the following. Enthalpies of formation (298 K, kcal/mol): Delta H f (CF 2O) = -144.7, Delta H f(CHFO) = -91.1, Delta H f (CFO (*)) = -41.6. Bond dissociation energy (0 K, kcal/mol): BDE(CFO-F) = 120.7, BDE(CHO-F) = 119.1, BDE(CFO-H) = 100.2. Ionization potential (eV): IP 1(CF 2O) = 13.04, IP 2(CF 2O) = 14.09, IP 1(CHFO) = 12.41, IP 2(CHFO) = 13.99, IP 1(CFO (*)) = 9.34. Proton affinity (298 K, kcal/mol), PA O(CF 2O) = 148.8, PA O(CHFO) = 156.7, PA F(CHFO) = 154.5 kcal/mol. Electron affinity: EA(CFO (*)) = 2.38 eV. Triplet-singlet separation gap (eV): Delta E T1-S0(CF 2O) = 4.47, Delta E T1-S0(CHFO) = 4.36. Triplet-triplet transition energy (eV): Delta E T2-T1(CF 2O) = 0.44. The new calculated values contribute to solving some persistent discrepancies in the literature. The effects of F-atoms on thermochemical parameters are not linearly additive, and the changes are largely dominated by the first F-substitution. On the basis of the calculated proton affinities of CF 2O and CF 3OH, the nucleophilicities of the oxygen atoms are, within computational errors, the same in both compounds.

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Section: Resultsmentioning

confidence: 99%

Thermochemical Parameters of CHFO and CF₂O

2008

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“…The degree of the dissociation of H 2 ͑D 2 ͒ was measured as 50%. 19 Molecular reactants were introduced 3.5 cm upstream of the observation window. Typical concentrations of GeH 4 and HI in the flow reactor were about 2ϫ10 13 molecule cm Ϫ3 .…”

Section: Experimental Methodsmentioning

confidence: 99%

Dynamics of OH and OD radical reactions with HI and GeH4 as studied by infrared chemiluminescence of the H2O and HDO products

Butkovskaya

Setser

1997

The Journal of Chemical Physics

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Articles you may be interested inAccurate combined-hyperbolic-inverse-power-representation of ab initio potential energy surface for the hydroperoxyl radical and dynamics study of O + OH reaction A laser photolysis/time-resolved Fourier transform infrared emission study of OH (X 2 Π,v) produced in the reaction of alkyl radicals with O ( 3 P)The infrared chemiluminescence of vibrationally excited H 2 O and HDO from the highly exothermic reactions of OH and OD radicals with HI and GeH 4 was observed in the 2200-5500 cm Ϫ1 range. The experiments utilized a fast-flow reactor with 0.3-1 Torr of Ar carrier gas at 300 K; the OH͑OD͒ radicals were produced via the H͑D͒ϩNO 2 reaction and the H or D atoms were generated by a discharge in a H 2 ͑D 2 ͒/Ar mixture. The H 2 O and HOD vibrational distributions were determined by computer simulation of the emission spectra in the 2200-3900 cm Ϫ1 range. The total vibrational energy released to H 2 O and HOD molecules is, respectively, ͗ f v ͘ ϭ 0.36 and 0.41 from HI and ͗ f v ͘ ϭ 0.46 and 0.51 from GeH 4 . These values are significantly smaller than for the reactions of OH and OD with HBr, ͗ f v ͘ ϭ 0.61 and 0.65. The populations of the O-H stretching vibration of HOD and the collisionally coupled 1 and 3 stretching modes of H 2 O decrease with increasing vibrational energy. In contrast, the vibrational distribution from the HBr reaction is inverted. The bending mode distributions in all stretching states of H 2 O and HOD extend to the thermodynamic limit of each reaction. A surprisal analysis was made for H 2 O͑HOD͒ distributions from the title reactions and compared with that for OH͑OD͒ϩHBr. The surprisal analysis tends to confirm that the dynamics for the HI and GeH 4 reactions differ from the HBr reaction. The HI reaction may proceed mainly via addition-migration, while the GeH 4 reaction may involve both direct abstraction and addition-migration. A rate constant for the OHϩGeH 4 →H 2 OϩGeH 3 reaction was evaluated by comparing the H 2 O emission intensities with that of the OHϩHBr→H 2 OϩBr reaction, k GeH 4 /k HBr ϭ 6.5 Ϯ 0.9. Secondary kinetic-isotope effects, k OH /k OD ϭ 1.4 Ϯ 0.1, 1.0Ϯ0.2, and 1.3Ϯ0.2, were determined for reactions of OH and OD with GeH 4 , HI, and HBr, respectively, by comparing the relative H 2 O and HOD emission intensities.

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“…Thus, the calculated E 0 (HF) and E 0 (HCl) for CFCl 2 SH and CF 3 SH in Table can be considered reliable until experimental results are available. Figure illustrates that the E 0 (HF) = 200 ± 3 kJ/mol for CF 2 ClSH, CFCl 2 SH, and CF 3 SH and the CF 3 OH value is only 12 kJ/mol lower. By contrast , the calculated and experimental E 0 (HF) for CF 2 ClCH 3 are in agreement, but both are higher by at least 90 kJ/mol (Table ) than for the halothiols or trifluoromethanol.…”

Section: Discussionmentioning

confidence: 94%

Unimolecular Rate Constants for the HF and HCl Elimination Reactions from Chemically Activated CF₂ClSH

Rossabi

Smith

Heard

et al. 2015

Int J of Chemical Kinetics

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Chemically activated CF 3 SH, CFCl 2 SH, and CF 2 ClSH were formed through combination of SH and CF 3 , CFCl 2 , and CF 2 Cl radicals, respectively. The SH radical was prepared by abstraction of an H-atom from H 2 S by the halocarbon radical produced during photolysis of (CF 3 ) 2 C=O, (CFCl 2 ) 2 C=O, or (CF 2 Cl) 2 C=O. 1,2-HX (X = F, Cl) elimination reactions were observed from CF 3 SH, CFCl 2 SH, and CF 2 ClSH with products detected by GC-MS. The combination reaction of CF 2 Cl radicals with SH radicals prepared CF 2 ClSH molecules with approximately 318 kJ/mol of internal energy. The experimental rate constants for elimination of HCl and HF from CF 2 ClSH were 3 ± 3 × 10 10 and 2 ± 1 × 10 9 s −1 , respectively. Comparison to Rice-Ramsperger-Kassel-Marcus (RRKM) calculated rate constants assigned the threshold energies as 171 ± 12 and 205 ± 12 kJ/mol for the unimolecular elimination of HCl and HF, respectively. Theoretical calculations using the B3PW91, MP2, and M062X methods with the 6311+G(2d,p) and 6-31G(d',p') basis sets established that for a specific method the threshold energies differ by only 4 kJ/mol between the two different basis sets. There was wide variation among the three methods, but the M062X approach appeared to give threshold energies closest to the experimental values. Chemically activated CF 3 SH and CFCl 2 SH were also prepared with about 318 kcal mol −1 of internal energy, and the HX (X = F, Cl) elimination reactions were observed. Only HCl loss was detected from CFCl 2 SH, but the rate was too fast to measure with our kinetic method; however, based on our detection limit the HF elimination channel is at least 50 times slower. C

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An Infrared Chemiluminescence Study of the Reactions of Hydrogen Atoms with CF3OCl and CF3O

Cited by 18 publications

References 10 publications

Thermochemical Parameters of CHFO and CF₂O

Thermochemical Parameters of CHFO and CF₂O

Dynamics of OH and OD radical reactions with HI and GeH4 as studied by infrared chemiluminescence of the H2O and HDO products

Unimolecular Rate Constants for the HF and HCl Elimination Reactions from Chemically Activated CF₂ClSH

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An Infrared Chemiluminescence Study of the Reactions of Hydrogen Atoms with CF3OCl and CF3O

Cited by 18 publications

References 10 publications

Thermochemical Parameters of CHFO and CF2O

Thermochemical Parameters of CHFO and CF2O

Dynamics of OH and OD radical reactions with HI and GeH4 as studied by infrared chemiluminescence of the H2O and HDO products

Unimolecular Rate Constants for the HF and HCl Elimination Reactions from Chemically Activated CF2ClSH

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Thermochemical Parameters of CHFO and CF₂O

Thermochemical Parameters of CHFO and CF₂O

Unimolecular Rate Constants for the HF and HCl Elimination Reactions from Chemically Activated CF₂ClSH