Addition reactions methane

Irradiation of ethyleneimine (341,342) with light of short wavelength ia the gas phase has been carried out direcdy and with sensitization (343—349). Photolysis products found were hydrogen, nitrogen, ethylene, ammonium, saturated hydrocarbons (methane, ethane, propane, / -butane), and the dimer of the ethyleneimino radical. The nature and the amount of the reaction products is highly dependent on the conditions used. For example, the photoproducts identified ia a fast flow photoreactor iacluded hydrocyanic acid and acetonitrile (345), ia addition to those found ia a steady state system. The reaction of hydrogen radicals with ethyleneimine results ia the formation of hydrocyanic acid ia addition to methane (350). Important processes ia the photolysis of ethyleneimine are nitrene extmsion and homolysis of the N—H bond, as suggested and simulated by ab initio SCF calculations (351). The occurrence of ethyleneimine as an iatermediate ia the photolytic formation of hydrocyanic acid from acetylene and ammonia ia the atmosphere of the planet Jupiter has been postulated (352), but is disputed (353). 

Addition of methane to the ion source at a pressure of about 0.5 Torr causes almost all of the electrons entering the ion source to collide with methane molecules. The first event is the expected production of a molecular ion (eq. 3). The molecular ion can then undergo fragmentation (eq. 4) or because of the high pressure of neutral methane, ion-molecule reactions can occur (eqs. 5 and 6). 

Snider and coworkers125 have reported the Lewis acid catalyzed [2 + 2]cycloaddition of (phenylsulfonyl)allene 112. The reaction with methylenecyclohexane in dichloro-methane gives a 25% yield of an 8 1 mixture of 210 and 211 (equation 132). An addition reaction of l-(p-tolylsulfonyl)ethylene with enamines gives aminocyanobutanes via the zwitterionic intermediate (212) as shown in equation 133126. 

Waters61 have measured relative rates of p-toluenesulfonyl radical addition to substituted styrenes, deducing from the value of p + = — 0.50 in the Hammett plot that the sulfonyl radical has an electrophilic character (equation 21). Further indications that sulfonyl radicals are strongly electrophilic have been obtained by Takahara and coworkers62, who measured relative reactivities for the addition reactions of benzenesulfonyl radicals to various vinyl monomers and plotted rate constants versus Hammett s Alfrey-Price s e values these relative rates are spread over a wide range, for example, acrylonitrile (0.006), methyl methacrylate (0.08), styrene (1.00) and a-methylstyrene (3.21). The relative rates for the addition reaction of p-methylstyrene to styrene towards methane- and p-substituted benzenesulfonyl radicals are almost the same in accord with their type structure discussed earlier in this chapter. 

The reaction of [MeCo(DMG)2py] in DMF with 1,4-butanedithiol in an atmosphere of COj produces small amounts (up to 1%) of acetic acid in addition to methane 157). 

The main by-products of the reaction were ethane, CH3F, CH3CI, and propane. The selectivities as a function of time are depicted in Figure 7a and b. At low hydrogen to CCI2F2 feed ratios the selectivities to ethane and propane are higher. Addition of methane or CHCIF2 to the feed also leads to an increase in the selectivities to ethane and propane, methane CHClFj... 

Thus it is clear from both the remarkable constant selectivity to methane and the influence of addition of methane on the selectivities to CHCIF2 and CH2F2, that the serial reaction mechanism has to be modified in order to explain the observed phenomena. Therefore, more measurements will be performed in order to determine the adsorption of CFCs on the metal surface and the influence of other products, such as CH2F2 and HCl on the catalyst performance [11]. 

In some cases, microorganisms can transform a contaminant, but they are not able to use this compound as a source of energy or carbon. This biotransformation is often called co-metabolism. In co-metabolism, the transformation of the compound is an incidental reaction catalyzed by enzymes, which are involved in the normal microbial metabolism.33 A well-known example of co-metabolism is the degradation of (TCE) by methanotrophic bacteria, a group of bacteria that use methane as their source of carbon and energy. When metabolizing methane, methanotrophs produce the enzyme methane monooxygenase, which catalyzes the oxidation of TCE and other chlorinated aliphatics under aerobic conditions.34 In addition to methane, toluene and phenol have been used as primary substrates to stimulate the aerobic co-metabolism of chlorinated solvents. 

In this chapter, we will study the elementary reaction steps of these mechanisms focusing primarily on the anthraphos systems. This chapter begins with a description of the impact of different methods (coupled cluster, configuration interaction and various DFT functionals), different basis sets, and phosphine substituents on the oxidative addition of methane to a related Ir system, [CpIr(III)(PH3)Me]+. Then, it compares the elementary reaction steps, including the effect of reaction conditions such as temperature, hydrogen pressure, alkane and alkene concentration, phosphine substituents and alternative metals (Rh). Finally, it considers how these elementary steps constitute the reaction mechanisms. Additional computational details are provided at the end of the chapter. 

The structure of a soluble prepolyner, resulting from the addition reaction of bisnaleimidodiphenyl methane to diallyl bisphenol A at approximately ISO °C, is confirmed by a detailed high resolution IMR... 

Fluorotris(trimethylsilyl)methane addition reactions. Synthesis of... 

In a number of cases, an addition reaction of OH radicals to olefins has been required to explain several of the major products. Although OH abstracting from olefins and H02 reactions with olefins can also explain some of the products, only the addition reaction is uniquely satisfactory. Thus, it is difficult to see how CH3 radicals, required to explain the presence of methane, can be obtained from C2H3 radicals which would be formed in an abstraction reaction of OH with C2H4. Similarly, while acetone and propylene can be plausibly formed if H02 attack is mainly responsible for the removal of 2-butene, it is not easy to see how the large quantities of methane are produced. It is not possible, of course,... 

As you can see, the reaction formally amounts to the addition of methanal as H—CHO to the alkene double bond. Because one additional carbon atom is introduced as a formyl CHO group, the reaction often is called hydroformylation, although the older name, oxo reaction, is widely used. 

Exercise 17-21 a. A useful modification of aldol addition to methanal, known as the Mannich reaction, uses a secondary amine (usually as its hydrochloride salt) to selectively introduce one carbon atom at the alpha position of an aldehyde or ketone. The actual product is the salt of an amino ketone. For example,... 

Many phenols undergo aldol-like addition reactions with carbonyl compounds in the presence of acids or bases. Thus benzenol reacts with methanal under mild alkaline conditions to form (4-hydroxyphenyl)methanol ... 

At present this method is excluded by a more economical process of methane reforming (considered in Section XIV). The exhaustion of natural gas resources may, however, restore the importance of coal gasification. In addition, reaction (377) is a constituent part of the blast furnace process. Reaction (378) is employed in the production of activated charcoal. 

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