Chain elongation during thermolysis of tetrafluoroethylene and hexafluoropropylene: Modeling of mechanistic hypotheses and elucidation of data needs

Poutsma, Marvin L.

doi:10.1016/j.jaap.2011.04.006

Cited by 11 publications

(17 citation statements)

References 98 publications

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“…19,20 In agreement with the calculations of Yokoyama et al 2) does not involve the same biradical intermediate. Instead, it has its own transition state to form C 3 F 6 + CF 2 , the latter according to our calculations at somewhat higher energies than for reaction (1).…”

Section: Quantum-chemical and Kinetic Modeling Of The Primary Dissoci...supporting

confidence: 63%

“…Octafluorocyclobutane, c-C 4 F 8 , is an important intermediate in the thermolysis of tetrafluoroethene, C 2 F 4 , thus constituting evidence for a chain elongation during this process. 1,2 Besides c-C 4 F 8 , substantial quantities of CF 3 CF = CF 2 , C 3 F 6 , and CF 2 = C(CF 3 ) 2 , i-C 4 F 8 have been observed earlier in this interesting reaction system. While it is well established that singlet difluorocarbene, CF 2 , plays an important role in the kinetics, it remains unclear whether C 3 F 6 is a primary product of the decomposition of c-C 4 F 8 or whether it arises from the secondary interaction of CF 2 with C 2 F 4 .…”

Section: Introductionmentioning

confidence: 64%

“…14 and the discussions by Poutsma1 we found that reaction (1) proceeds as a two-step process with the intermediate formation of the 1,4-biradical CF 2 CF 2 CF 2 CF 2 , followed by break-up of the central C-C bond leading to 2 C 2 F 4 . On the other hand, reaction (2) was found to involve a single transition state only.…”

mentioning

confidence: 66%

“…3 This gave us the opportunity to monitor the primary steps of the dissociations of C 2 F 4 , 3 C 3 F 6 , 4 and c-C 3 F 6 5 with respect to their rates and branching pathways. In continuation of these studies we now try to distinguish between the two primary dissociation pathways of c-C 4 F 8 , c-C 4 F 8 -2 C 2 F 4 (1) and c-C 4 F 8 -CF 2 + C 3 F 6 (2) where reaction (1) would be followed by…”

Section: Introductionmentioning

confidence: 99%

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Shock wave study and theoretical modeling of the thermal decomposition of c-C₄F₈

Cobos

Hintzer²,

Sölter

et al. 2015

Phys. Chem. Chem. Phys.

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The thermal dissociation of octafluorocyclobutane, c-C4F8, was studied in shock waves over the range 1150-2300 K by recording UV absorption signals of CF2. It was found that the primary reaction nearly exclusively produces 2 C2F4 which afterwards decomposes to 4 CF2. A primary reaction leading to CF2 + C3F6 is not detected (an upper limit to the yield of the latter channel was found to be about 10 percent). The temperature range of earlier single pulse shock wave experiments was extended. The reaction was shown to be close to its high pressure limit. Combining high and low temperature results leads to a rate constant for the primary dissociation of k1 = 10(15.97) exp(-310.5 kJ mol(-1)/RT) s(-1) in the range 630-1330 K, over which k1 varies over nearly 14 orders of magnitude. Calculations of the energetics of the reaction pathway and the rate constants support the conclusions from the experiments. Also they shed light on the role of the 1,4-biradical CF2CF2CF2CF2 as an intermediate of the reaction.

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Section: Quantum-chemical and Kinetic Modeling Of The Primary Dissoci...supporting

confidence: 63%

Section: Introductionmentioning

confidence: 64%

mentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Shock wave study and theoretical modeling of the thermal decomposition of c-C₄F₈

Cobos

Hintzer²,

Sölter

et al. 2015

Phys. Chem. Chem. Phys.

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“…Homogeneous decomposition reaction [26], elimination reaction [27], as well as isomerization followed by elimination reaction [28] are usually the three main reaction pathways of thermal decomposition of unsaturated alkene. We can also refer to the decomposition pathways of the smallest perfluorocycloalkanes c-C 3 F 6 and c-C 4 F 8 [29], because their thermal chemistry is interwoven with that of the perfluoro-olefins. The above three reactions of Octafluoro-2-butene are demonstrated (Figure 2), with all the energy barriers calculated in the unit of kcal mol À1 .…”

Section: Decomposition Mechanism Of Octafluoro-2-butenementioning

confidence: 99%

In depth study on the fire‐extinguishing mechanism of Octafluoro‐2‐butene as a new promising Halon substitute

Wang

et al. 2022

Int J of Quantum Chemistry

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Due to the serious destruction of Halon to the ozone layer, it is significant to explore the fire‐extinguishing agent with zero ozone depletion potential (ODP). At the molecular structure level, Octafluoro‐2‐butene has a special arrangement of fluorine atoms, endowing itself with better potential to replace Halon than the reported perfluoroalkanes and hydrofluoroethylenes (HFOs). However, as a new Halon substitute, the fire‐extinguishing mechanism of Octafluoro‐2‐butene has not been studied. In this paper, the thermal decomposition and fire‐extinguishing mechanism of Octafluoro‐2‐butene were studied by density functional theory (DFT) and the rate constants of each reaction path were calculated for the first time. The calculation results show that Octafluoro‐2‐butene produces a large number of fire extinguishing groups and the rate constants of the main fire extinguishing paths are fast. Noteworthy, there is no combustion radical produced during extinguishing. In addition, the thermal decomposition of Octafluoro‐2‐butene mostly produced halogenated alkane with the better ability to react with chain radicals. The theoretical results show that Octafluoro‐2‐butene is a promising Halon substitute, and its practicability can be further studied and comprehensively evaluated.

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Theoretical and experimental studies on the thermal decomposition and fire‐extinguishing performance of 1,1,2,3,3,3‐hexafluoro‐1‐propene (R1216)

Li,

Zhang,

et al. 2023

Int J of Quantum Chemistry

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Due to the severe damage of Halon to the stratospheric ozone layer, the urgent need for substitutions for Halon has driven the search for potential alternatives. As a perfluoroolefin substance, R1216 (1,1,2,3,3,3‐hexafluoro‐1‐propene) has a similar chemical structure to the widely used 2‐bromo‐3,3,3‐trifluoro‐1‐ene (CF3CBrCH2, 2‐BTP) extinguishants. This study revealed the thermal decomposition and fire‐extinguishing performance of R1216 using theoretical calculations and experimental measurements. It was found that R1216 has high thermal stability and does not decompose at 600°C, and not only achieves the purpose of chemical extinguishment by generating perfluoroalkanes, perfluoroolefins and CF3· radicals that can capture H· and OH· radicals in the flame to interrupt the chain reactions of combustion, but also achieve the goal of cooling by absorbing heat through bond breaking. A combination of physical and chemical inhibition makes R1216 ideal for fire suppression (6.78 and 7.40 vol% for methane and propane flames, respectively). R1216 does not contain Br· and has a global warming potential of 0, which is more environmentally friendly. These findings suggested that R1216 may be a potential Halon substitute with promising applications and deserved further evaluation.

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Chain elongation during thermolysis of tetrafluoroethylene and hexafluoropropylene: Modeling of mechanistic hypotheses and elucidation of data needs

Cited by 11 publications

References 98 publications

Shock wave study and theoretical modeling of the thermal decomposition of c-C₄F₈

Shock wave study and theoretical modeling of the thermal decomposition of c-C₄F₈

In depth study on the fire‐extinguishing mechanism of Octafluoro‐2‐butene as a new promising Halon substitute

Theoretical and experimental studies on the thermal decomposition and fire‐extinguishing performance of 1,1,2,3,3,3‐hexafluoro‐1‐propene (R1216)

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Chain elongation during thermolysis of tetrafluoroethylene and hexafluoropropylene: Modeling of mechanistic hypotheses and elucidation of data needs

Cited by 11 publications

References 98 publications

Shock wave study and theoretical modeling of the thermal decomposition of c-C4F8

Shock wave study and theoretical modeling of the thermal decomposition of c-C4F8

In depth study on the fire‐extinguishing mechanism of Octafluoro‐2‐butene as a new promising Halon substitute

Theoretical and experimental studies on the thermal decomposition and fire‐extinguishing performance of 1,1,2,3,3,3‐hexafluoro‐1‐propene (R1216)

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Shock wave study and theoretical modeling of the thermal decomposition of c-C₄F₈

Shock wave study and theoretical modeling of the thermal decomposition of c-C₄F₈