Methane reaction with

HO oxidation of CO is much faster than the reaction with methane, resulting in a mean CO lifetime of about two months, but considerably slower than reaction with the majority of the nonmethane hydrocarbons. Table I gives representative removal rates for a number of atmospheric organic compounds their atmospheric lifetimes are the reciprocals of these removal rates (see Equation E4, below). The reaction sequence R31, R13, R14, R15 constitutes one of many tropospheric chain reactions that use CO or hydrocarbons as fuel in the production of tropospheric ozone. These four reactions (if not diverted through other pathways) produce the net reaction... 

For transition-metal catalyzed hydroxylation of alkane C-H bonds, the reactions of alkanes with platinum(II) complexes were the most successful. In an aqueous solution of hexachloroplatinic acid and Na2PtCl4, alkanes were converted into a mixture of isomeric alkyl chlorides, alcohols, and ketones, and the platinum(IV) is reduced to platinum(II).7 The kinetics of the reaction with methane as the alkane have been described in detail.8... 

The oxidation and the partial oxidation method, the CO2 from an ammonia plant in a reaction with methane, and water all produce different ratios of CO and H2. In addition, CO2 can be removed by solvent extraction. So, the trick is to use two or three of these processes to get the C0 H2 ratio to about 1 2. 

Figure 3.15 Propane crossed metathesis reaction with methane under SObar at 250°C, catalyzed by (=SiO)2TaH (3) (300mg, d = l.SmLmin-, CH4 C3Hg = 1250 1).

A subsequent study using neopentane as the alkane substrate gave evidence in support of the same mechanism, and also allowed resolution of near-coincident y(CO) absorptions due to [Cp Rh(CO)Kr] (1946 cm ) and [Cp Rh(CO)(di2-neopen-tane)] (1947 cm ) [18]. Further studies were able to quantify the reactivity of [Cp Rh(CO)Kr] towards a range of alkanes [20]. It was found that binding of the alkane to Rh becomes more favorable, thermodynamically, as the alkane size is increased, but that the rate of the C-H oxidative addition step shows less variation with linear alkane chain length. No reaction with methane was observed, which was explained by the ineffective binding of methane (relative to excess Kr) to Rh. 

Reaction with methane at 2,100°C produces hafnium carbide, a dark-gray, brittle solid, which is not a true stoichiometric compound. It probably is a homogeneous mixture in which carbon impregnates interstitial sites in the face-centered cubic lattice of hafnium. 

The destruction of 03 by chlorine and bromine can be short-circuited by removing either Cl and Br or, alternatively, CIO and BrO. For chlorine atoms, this occurs by reaction with methane that has been transported from the troposphere ... 

The reaction of CBr4 with potassium is reported to generate free C atoms and the rate constants for reaction with methane, ethylene, and benzene have been reported. The reaction of nitrogen atoms with CN radicals has also been used as a C atom source. Carbon atoms have also been produced by passing organics through a microwave discharge. ... 

Guided-ion-beam mass spectrometry (GIBMS) was used to study the reaction of CoO+ with CH4 and with D2 (.223). The exothermic reaction with methane, Eq. (4), was found to have an activation barrier of... 

When the temperature is too low for methoxy to dissociate thermally, it may react through a number of H abstraction reactions to form methanol. These include reaction with methane (R19) and with formaldehyde... 

Hence, (V111-58) is the rate-determining step for the ClO-Cl catalytic cycle. The chain-terminating step is the reaction with methane to form HCI... 

Among other reactions, it is worth mentioning the formation of hydrogen chloride in a reaction with methane, molecular hydrogen, or other constituents such as formaldehyde, H2CO, or hydrogen peroxide, H202. An example is... 

P-site (125) is favored by 3.3 kcal/mol over protonation at the C-site (122). However, protonation at the carbon is favored for cations 120 and 121. All three dicationic species 123, 124, and 125, are predicted to be kinetically stable with significant energy barriers towards homolytic or heterolytic fragmantation reactions. In studies of isodesmic reactions with methane, the dicationic species are shown to be far more reactive (eqs 36-37). 

These reactions supply atomic hydrogen to lower parts of atmospheres and thus initiate numerous reactions of carbon, oxygen, and nitrogen species. The most important are the reactions with methane (equations 8.8-8.10), which finally yield... 

The selectivity of attack of radicals at different hydrogens has been extensively utilized as a tool to characterize the reactivity and nature of the various radicals. The data in Table 22 show that there is a qualitative relation between the selectivity of a radical, i.e., its relative ability to abstract methyl, primary, secondary and tertiary hydrogens, and its reactivity represented by the Arrhenius activation energy, E, for the reaction, with methane (Kerr, 1973). This relationship is in accord with the reactivity- selectivity principle. The fact that the ease of abstraction of the different hydrogens runs in the same sequence as C—H bond strengths (i.e., methyl > primary > secondary > tertiary), suggests that the activation energy is related to... 

The most effective wavelength of light is a blue color that is strongly absorbed by chlorine gas. This finding implies that light is absorbed by the chlorine molecule, activating chlorine so that it initiates the reaction with methane. 

The rare earth metal complex Cp2LuH catalyzes the hydrogenation of al-kenes and on reaction with methane gives Cp2Lu(CH3) and H2. Suggest probable mechanisms. 

A chlorine atom may go through this cycle many thousands of times before it is removed in the form of HC1 following reaction with methane ... 

Other ion-molecule reactions with methane will occur in the plasma, such as... 

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