Ethane from decomposition

An intramolecular isotope effect of 7( = /CHCH //ch3cd3) has been found for the loss of ethane from the decomposition of the metastable 3-hydroxypentane ion [CD3CH2CH(OH)CH2CH3]t [363]. The isotope... 

However, if in nonaqueous solutions (discussed next) the oxidations also proceed through oxypalladation adducts, then the two mechanisms of decomposition of the oxypalladation adducts would predict diflFerent products. First, let us consider the mechanism of Jira, Sedlmeier, and Smidt (Reactions 50-53). In this case OH in II (Reaction 52) is replaced by OR. Decomposition via Reaction 55 is impossible, so II must decompose by solvolysis. This would give 1,1-disubstituted ethanes from ethylene oxidation. On the other hand, the first suggestion (Reaction 48) would probably be more consistent with formation of the vinyl compounds since hydride elimination should be completed if a rapid rearrangement of electrons to give acetaldehyde cannot occur. Evidence exists that 1,1-disubstituted ethanes are the initial products in methanol, and in acetic acid it is claimed that both vinyl acetate and 1,1-diace-toxyethane are initial products this suggests that in this solvent competition exists between palladium (II) hydride elimination and acetate attack. However, until now there have been no detailed studies of the oxidation under conditions where 1,1-disubstituted products are formed. More work is needed before the course of the reaction under these conditions is completely understood. 

As in steam cracking, a large number of by-products is produced. Some of them result from the consecutive reactions of the chlorination of vinyl chloride and of its derivatives obtained by dehydrochlorination (tri-, tetra-, pentachloroethane, perchloro-ethane, di-, trichloroethylene. perchloroethyleneX and the others from the hydrochlorination of vinyl chloride il.l-dichloroethane), while others result from decomposition reactions (acetylene, cokei or conversion of impurities initially present (hydrocarbons such as ethylene, butadiene and benzene, chlorinated derivatives such as chloroprene, methyl and ethyl Chlorides, chloroform, carbon tetrachloride, eta, and hydrogen) ... 

Kinetics of decomposition at short times (methyl radical from the n-butane [825], 2, 2-dimethylbutane [240] and 2, 2-dimethylpentane [240] ions, loss of ethyl from n-heptane, n-hexane and n-octane ions [522, 825], loss of methane from the neopentane ion [825], and loss of ethane from the 3-ethylpentane ion... 

The radiolysis product yields in the presence of ion scavenger (Table III) also show that ethane is not formed from neutralization of stable ions. Therefore, the remainder of the ethane product (above that indicated to result from neutral decomposition) must be produced by an ion-molecule process—i.e., a yield of G = 1.47. The ion-molecule reactions previously listed show that ethylene ions react with ethyl chloride to form ethane. From the relative rates indicated for Reactions 3a-3d and the ethane yield just derived, a relative yield of 2.46 may be deduced for the ionic fragmentation to ethylene ion in the radiolysis. 

Reductive elimination reactions are responsible for the final C-C/C-X bond formation step in catalytic processes. In principle, C-bound or any other anionic pincer ligands could engage in reductive couphng reactions, bringing about the decomposition of the pincer complex. In order to enable catalysis by such complexes, it is mandatory to avoid reductive elimination reactions involving the pincer ligand itself Fortunately, this seems to be usually the case. For example, reductive elimination of ethane from the Pd(IV) pincer complex 18 (Scheme 2.3) is preferred... 

Although there has been considerable interest in oxidative-addition reactions there is less information available on the reverse reaction, reductive elimination. Kinetic studies of the decomposition of c-CPtXMesLa] (X = Cl or Br, L = PMe Ph X = I, L = PMcs, PMeaPh, or PMePh ) are consistent with a mechanian involving dissociation of a phosphine ligand followed by elimination of ethane from the live-co-ordinate intermediate. Activation parameters are given in Table 3. Methyl... 

British Foreign Minister Ernest Bevin once said that "The Kingdom of Heaven runs on righteousness, but the Kingdom of Earth tuns on alkanes." Well, actually he said "tuns on oil" not "runs on alkanes," but they re essentially the same. By far, the major sources of alkanes are the world s natural gas and petroleum deposits. Laid down eons ago, these deposits are thought to be derived from the decomposition of plant and animal matter, primarily of marine origin. Natural gas consists chiefly of methane but also contains ethane, propane, and butane. Petroleum is a complex mixture of hydrocarbons that must be separated into fractions and then further refined before it can be used. 

The polarization of biphenyl, deserves special comment. If, as indicated in Scheme 2, its immediate precursor is a radical pair consisting of two phenyl radicals, then it should be formed without detectable net polarization since if Ag = 0. Analogous results have been reported in the decomposition of other peroxides for example, ethane formed from acetyl peroxide shows net emission. To account for this, it has been suggested (Kaptein, 1971b, 1972b Kaptein et al., 1972) that nuclear spm selection which occurs in the primary radical pair—in... 

A corresponding correlation is obtained for the rate constants of a,a -phenyl substituted alkanes 26 (R1 = C6H5, R2 = H, R3 = alkyl) (see Fig. 1 )41). It has, however, a different slope and a different axis intercept. When both correlations are extrapolated to ESp = 0, a difference of about 16 kcal/mol in AG is found. This value is not unexpected because in the decomposition of a,a -phenyl substituted ethanes (Table 5, no. 22—27) resonance stabilized secondary benzyl radicals are formed. From Fig. 1 therefore a resonance energy of about 8 kcal/mol for a secondary benzyl radical is deduced. This is of the expected order of magnitude54. ... 

Selective transformations Selective styrene ring opening [103] One-pot domino process for regioselective synthesis of a-carbonyl furans [104] Tandem process for synthesis of quinoxalines [105] Atmospheric oxidation of toluene [106] Cyclohexane oxidation [107] Synthesis of imines from alcohols [108] Synthesis of 2-aminodiphenylamine [109] 9H-Fluorene oxidation [110] Dehydrogenation of ethane in the presence of C02 [111] Decomposition of methane [112] Carbon monoxide oxidation [113]... 

The photochemistry of Titan s atmosphere can be summarized as follows the unsaturated compounds are formed from HCN and C2H2, which is derived from CH4. Methane decomposition leads to further ethane formation. 

It has been generally accepted that the thermal decomposition of paraffinic hydrocarbons proceeds via a free radical chain mechanism [2], In order to explain the different product distributions obtained in terms of experimental conditions (temperature, pressure), two mechanisms were proposed. The first one was by Kossiakoff and Rice [3], This R-K model comes from the studies of low molecular weight alkanes at high temperature (> 600 °C) and atmospheric pressure. In these conditions, the unimolecular reactions are favoured. The alkyl radicals undergo successive decomposition by [3-scission, the main primary products are methane, ethane and 1-alkenes [4], The second one was proposed by Fabuss, Smith and Satterfield [5]. It is adapted to low temperature (< 450 °C) but high pressure (> 100 bar). In this case, the bimolecular reactions are favoured (radical addition, hydrogen abstraction). Thus, an equimolar distribution ofn-alkanes and 1-alkenes is obtained. 

The data of the table are of the decomposition of di-t-butyl peroxide to acetone and ethane at 188 C in a tubular flow reactor of 82.4 cc volume. The concentrations are in mol/liter and flow rate is in cc/sec. A carrier gas was used, and any volume change resulting from the reaction may be taken negligible. Find the rate equation. 

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