Relative reactivities of some carbon-hydrogen bonds in hydrogen abstraction by methyl radicals at 950 K

Kopinke, Frank‐Dieter; Remmler, M.; Mensing, H.; Hugo, P.

doi:10.1021/j100055a021

Cited by 5 publications

(4 citation statements)

References 11 publications

(14 reference statements)

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“…The KIE value reported for CH 4 /CD 4 ranges from 3.8 to 4.6 536 and is computed as 3.2. 537 The kinetics of the reaction of small alkanes with methyl radicals were evaluated at moderate to combustion temperatures, and the relative 3°:2°:1°reactivities were estimated as 61:4.8:1 at 350 K. 538 This agrees with the trend in the experimental 539 activation energies (11.0, 12.5, and 13.2 kcal mol -1 , respectively). The influence of chloro/fluoro substitution on the reaction of methane with methyl radicals was studied computationally at MP2/6-31G(d,p)//HF/6-31G(d,p).…”

Section: Carbon-centered Radicalssupporting

confidence: 77%

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Selective Alkane Transformations via Radicals and Radical Cations: Insights into the Activation Step from Experiment and Theory

2002

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Section: Carbon-centered Radicalssupporting

confidence: 77%

“…The kinetics of the reaction of small alkanes with methyl radicals were evaluated at moderate to combustion temperatures, and the relative 3°:2°:1° reactivities were estimated as 61:4.8:1 at 350 K . This agrees with the trend in the experimental activation energies (11.0, 12.5, and 13.2 kcal mol -1 , respectively).…”

Section: 4 Carbon-centered Radicalssupporting

confidence: 76%

Selective Alkane Transformations via Radicals and Radical Cations: Insights into the Activation Step from Experiment and Theory

2002

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“…[134] Even for the methyl radical the observed 38:28:18 selectivities are 61 : 5 : 1 for small alkanes. [135] The involvement of the BrCH 2 radical increases the selectivities further with or without metal catalyst (Table 7, Entries 5 and 6). Simple trihalomethyl radicals are generated through photolytic, [136] ther- [a] Ar 2,4,5-tricyanobenzyl.…”

Section: Metal-free Alkane Halogenationsmentioning

confidence: 97%

Metal‐Free, Selective Alkane Functionalizations

2003

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The present overview of alkane functionalization reactions presents comparisons between radical and metal-initiated (sometimes metal-catalyzed) methodologies. While metal-catalyzed processes are excellent approaches to this problem, metal-free alternatives are equally if not, at least from an environmental and cost perspective, more useful. This conclusion is supported by the fact that many so-called metal-catalyzed reactions also work without the metal present, and the large variety of metals showing the same product distributions emphasizes that the metal often just aids in the generation of the active species, i.e., the metal itself is not participating in the crucial C À H activation step. Highly selective alkane functionalization reactions such as those derived from nitroxyl and related radicals as well as through radical reactions conducted in phase-transfer catalyzed systems are available but generally underutilized. These systems, in contrast to typical metalcatalyzed approaches, are also applicable to highly strained alkanes and offer the highest 38/28 C À H selectivities reported to date in a radical reaction. The article closes with representative experimental protocols for the PTC bromination of cubane as an example of the applicability of this method to strained hydrocarbons and the direct iodination of cyclohexane as well as adamantane as typical alkanes bearing secondary and tertiary C À H bonds.

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“…Experimental methods have been used to study the global warming species, in particular, the kinetics of their reactions and degradation rates and pathways [21][22][23][24][25][26][27][28] with other atmospheric species, including their branching ratios through competitive channels [29]. Advances in computational science and computer technology have made impacts in the research of chemical kinetics.…”

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confidence: 99%

Assessment of theoretical methods for the study of hydrogen abstraction kinetics of global warming gas species during their degradation and byproduct formation (IUPAC Technical Report)

Ramasami

Abdallah

Archibong

et al. 2013

Pure and Applied Chemistry

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Global climate change is a major concern as it leads to an increase in the average temperature of the earth's atmosphere. The existence and persistence of some gaseous species in the atmosphere contribute to global warming. Experimental techniques are used to study the kinetics and degradation of global warming gases. However, quantum mechanical methods are also useful for the kinetic and radiative forcing study of global warming species and can precede experimental investigations. Research has also been targeted to develop more adapted procedures using ab initio and density functional theory (DFT) methods. This report provides a global perspective, in simplified manner, of the theoretical studies of the degradation of gas species in the atmosphere with an emphasis on the hydrogen abstraction kinetics of global warming gas species during their degradation and byproduct formation. En route, the results obtained from these studies are analysed and compared with experimental data where available. Our analyses indicate that the theoretical predictions are in agreement with experimental findings but the predicted parameters are dependent on the method being used. Theoretical methods are used to predict the thermodynamic parameters of reactions, and, with relevance to this report, the global warming potential (GWP) index can also be calculated. This report can be useful for future investigations involving global warming gaseous species while providing suggestions on how computations can fill in data gaps when experimental data are unavailable.

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Relative reactivities of some carbon-hydrogen bonds in hydrogen abstraction by methyl radicals at 950 K

Cited by 5 publications

References 11 publications

Selective Alkane Transformations via Radicals and Radical Cations: Insights into the Activation Step from Experiment and Theory

Selective Alkane Transformations via Radicals and Radical Cations: Insights into the Activation Step from Experiment and Theory

Metal‐Free, Selective Alkane Functionalizations

Assessment of theoretical methods for the study of hydrogen abstraction kinetics of global warming gas species during their degradation and byproduct formation (IUPAC Technical Report)

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