Methane oxidative methylation with

A further possibility for side-chain alkylation of toluene is oxidative methylation with methane. Catalysts with occluded alkali metal oxides, prepared by impregnating zeolites with alkali metal hydroxides followed by calcination, usually exhibit better performance.441 Further enhancement was achieved by impregnating ion-exchanged zeolites 442 Significant improvements in stability and the yields of Cg hydrocarbons were also observed when NaX was impregnated with 13% MgO which was found to increase the amounts of active sites.443... 

A new approach we found is based on the initial bromination of methane to methyl bromide, which can be effected with good selectivity, although still in relatively low yields. Methyl bromide is easily separated from exeess methane, whieh is readily recyeled. Hydrolysis of methyl bromide to methyl alcohol and its dehydration to dimethyl ether are readily achieved. Importantly, HBr formed as by produet ean be oxidatively reeycled into bromine, making the overall proeess cat-alytie in bromine. 

Methane oxidations occur only by intermediate and high temperature mechanisms and have been reported not to support cool flames (104,105). However, others have reported that cool flames do occur in methane oxidation, even at temperatures >400 ° C (93,94,106,107). Since methyl radicals caimot participate in reactions 23 or 24, some other mechanism must be operative to achieve the quenching observed in methane cool flames. It has been proposed that the interaction of formaldehyde and its products with radicals decreases their concentrations and inhibits the whole oxidation process (93). 

Hallam SJ, PR Girguis, CM Preston, PM Richardson, EF DeLong (2003) Identification of methyl coenzyme M reductase A (merA) genes associated with methane-oxidizing archaea. Appl Environ Microbiol 69 5483-5491. 

According to Lunsford, most of the observations on methane oxidation over oxide catalysts may be interpreted in terms of methyl radical chemistry.41 Most experimental data support the role of surface O- ions in the formation of methyl radicals. The latter are transformed by reductive addition to methoxide ions, which decompose to formaldehyde or react with water to form methanol. Methyl radicals may desorb to the gas phase and participate in free-radical reactions to yield non-selective oxidation products. 

In 1947, Kinney (15) drew attention to a direct relationship between the amount of acetic acid formed on oxidizing coal with nitric acid and potassium dichromate and the yields of methane obtained by low temperature carbonization. The oxidation method leading to acetic acid is a variation of the standard Kuhn-Roth procedure, and hence what Kinney indicated as the methane yielding structure is obviously the methyl groups in coal. However, the relationship he pointed out can only be qualitative since true C-methyl content (as shown in the present work) cannot be obtained by any... 

HDA [HydroDeAlkylation] A proprietary dealkylation process for making benzene from toluene, xylenes, pyrolysis naphtha, and other petroleum refinery intermediates. The catalyst, typically chromium oxide or molybdenum oxide, together with hydrogen gas, removes the methyl groups from the aromatic hydrocarbons, converting them to methane. The process also converts cresols to phenol. Developed by Hydrocarbon Research with Atlantic Richfield Corporation and widely licensed worldwide. 

According to a report presented by Fu et al. [180], the influence of POSS-triol on epoxy-amine reaction depends mostly on the magnitude of AT (Tg -Tc) used. Since Tg for epoxy cured with linear aliphatic diamine—2-methyl-1,5-pentadiamine (MPDA)—was higher than the Tg of the same epoxy cured with diamine-terminated polypropylene oxide (PPO), when cured at the same temperature, epoxy-cured MPDA showed a greater improvement in the value of Tg. Moreover, the addition of POSS-triol in tetraglycidyl diamino diphenyl methane (TGDDM) cured with MPDA also increased the rubbery plateau modulus (Fig. 6). 

Ogura et al. [124] studied the photochemical and electrochemical oxidation of methane to methyl chloride and methanol. This room-temperature process evolved chlorine at a platinum anode followed by photochemical generation of CT (chloride radical) from CI2. The chloride radical subsequently oxidized methane gas (fed to the anode) to the methyl radical (CH3). The methyl radical reacted with chlorine gas to form methyl chloride which was immediately hydrolyzed to methanol. The formation of methyl chloride and methanol began at t.l V vs. SCE, which corresponds to the onset of chlorine evolution. 

Reaction of periodate-oxidized methyl a-D-glucopyranoside with nitro-methane and sodium methoxide gave an oci-nitro compound which, after acidification and reduction, gave methyl 3-amino-3-deoxy-a-D-mannopy-ranoside hydrochloride. ... 

Himbeline was readily identified as A -demethylhimbacine since methylation with formaldehyde-formic acid gave himbacine (2). The alkaloid was further characterized by its acetyl and methane sulfonyl derivatives rather surprisingly these derivatives could not be hydrolyzed under the usual conditions. In contrast to this unreactivity the double bond of himbeline was easily hydrogenated, readily suffered oxidation by permanganate to yield the lactone acid XVII, and was attacked by performic acid to give the epoxide and glycol. No explanations of these abnormal reactivities have been advanced. 

Horvath has reported conditions under which Pt11 is used to catalyze the conversion of methane to methyl chloride. The reaction conditions employed are indicated below, and avoid the hydrolysis of the methyl chloride to methanol. While the total quantity of methyl chloride formed is less than the amount of platinum initially present, the system is catalytic in Pt11 (Eq. 14), with PtIV serving as a stoichiometric oxidant and Cl2 stabilizing the system against precipitation of Pt° [61]. 

Two examples of low temperature, catalytic, methane oxidation by hydrogen peroxide should be included in this section. The first involves conversion to methanol using cis-[Ru(2,9-dimethyl-l,10-phenanthroline)(solvent)2](PF6)2 as the catalyst [39]. A ruthenium-oxo species has been proposed as the C-H activating species. In the second report, conversion of methane to methyl hydroperoxide is claimed [40]. The catalyst is a combination of [NBuJ V03 and pyrazine-2-carbox-ylic acid. While the mechanism is uncertain, the actual oxidant is believed to be dioxygen with HO derived from hydrogen peroxide acting as the initiator. 

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