Methane from toluene

A system may continue to react, as long as the Gibbs free energy keeps decreasing (AG < 0). This might occur, for example, when the chemical bonds in the products are stronger than those in the reactants. Such reactions are exothermic and proceed with a heat release. An example is the formation of benzene and methane from toluene and hydrogen mentioned in Chap. 1 for the HDA process ... 

Sulfuric acid is number 1 by far, with a volume of over 90 billion lb produced yearly in the U.S. It is way ahead of number 2, nitrogen, which is produced at more than 75 billion lb annually. The highest volume organic chemical is ethylene, the basic petrochemical used to synthesize so many other important organic chemicals. It is the leader of the basic seven organics—ethylene, propylene, the C4 mixture, benzene, toluene, xylene, and methane—from which all other important organic chemicals are derived. Methane does not itself appear in the list because it is not synthesized by a chemical process. However, it is the major constituent in natural gas and is used to make many other chemicals. 

Many investigators have also shown that toluene can be degraded under methanogenic conditions. The first report of this was that of Warder < / (1980) who measured a 5% 14C02 recovery and some methane from 14C-toluene after a 233-... 

Superhydride has also been used for the hydrogenolysis of alkyl toluene-p-sulphonates, and an illustrative example is given in Expt 5.4 for the preparation of cyclooctane from cyclooctyl toluene-p-sulphonate. A sodium borohydride hydrogenolysis of alkyl halides and of alkyl methane- and toluene-p-sulphonates under PTC conditions provides an interesting variant of this reaction.9... 

Reaction (6) occurs in hydrocarbon solvents. It shows that the hydrogens attached to carbon in hydrocarbons can be faintly acidic for in the reaction a hydrogen ion is transferred from toluene (CatUCHg) to the met hide ion, CHj Both toluene and methane are exceedingly weak acids, but toluene is thus shown to be more acidic than methane. 

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. 

Step 5. The distillate stream from the product column is salable benzene. Benzene quality can be affected primarily by two components, methane and toluene. Any methane that leaves in the bottoms of the stabilizer column contaminates the benzene product. The easy separation in the stabilizer column allows us to prevent this by using a temperature to set column steam rate (boilup). Toluene in the overhead of the product column also affects benzene quality. In this column the separation between benzene and toluene is also fairly easy. As a result, we can control product column boilup by using a tray temperature. To achieve on-aim product quality control, we most likely would use an on-line overhead composition analyzer to adjust the setpoint of this temperature controller,... 

In this configuration, the hydrogen and the methane from the demethanizer column are spUt into their component streams. The hydrogen is for use in various downstream processes and the methane is used as a fuel-gas stream. Bottoms from the de-ethaniser are further split into C3 and C4. stream. The C3 is treated similarly to the C2 to produce polymer grade propylene. After removing the C4 fraction, which is passed to downstream separation units, the heavy components form pyrolysis-gasoUne. The latter may be further separated to produce benzene, toluene and xylene. 

They used toluene as carrier gas, and in addition found small amounts of methane and dibenzyl, presumably formed from toluene by the obvious reactions. Rebbert and Laidler state that they were using the toluene carrier gas technique of Szwarc, but in fact they were attempting to use it under conditions where it has no apparent advantage. Szwarc intended that the toluene should mop up the radicals formed by the initial bond fission of the compound under investigation, but clearly this did not happen at the temperatures used here (200-240° G). In fact, the recombination of methyl radicals, which requires no activation energy, is more likely to... 

Imidazole sodium salt (10 mmol), dichloromcthane (20 ml) and methane-sulfonyl chloride (10 mmol) are mixed with stirring and cooling in an ice bath under nitrogen. After stirring at 35 C (24 h) (as for 1-benzoylimidazole, see Section 7.1.4) the mixture is pressure filtered and extracted with dichloromethane (3x5 ml) under nitrogen. The solvent is then removed, and the crude product (82%) is recrystallized from toluene, m.p. 85-87°C. 

How are we to account for the stability of the benzyl radical Bond dissociation energies indicate that 19 kcal/mole less energy (104 — 85) is needed to form the benzyl radical from toluene than to form the methyl radical from methane. 

Tris(trimethylsilyl)methyllithium (88), prepared from methyllithium and tris(trimethylsilyl)methane in THF, can be recrystallized from toluene to give colorless, transparent needles of the unique ate complex [Li(THF)4] [Li C(TMS)3 2] . The structure of one of the anions in this complex is shown as (89). This... 

Examples Oxidative coupling of methane (OCM), oxidative dehydrogenation of C -C4 alkanes, partial oxidation of methane to synthesis gasa, combined oxidative coupling of methane and toluene to styrene Surface-stabilized combustion, partial oxidation of methane to synthesis gasa, synthesis of cyanic acid from methane, ammonia, and oxygen3... 

The more endothermic Eq. 9.50 is, the weaker the acid will be. Therefore Table 9.5 may readily be used to compare gas-phase acid strengths, and HF is a weaker acid in the gas phase than are the other HX acids, as it is also in aqueous solution. In the same way. acetic acid (PACHlCOO- = + 459kJmol-l)isa weaker acid than trifluoroacetic acid (PACFlCOO- = + 1351 kJ mol- ). Which is the stronger acid, methane or toluene Does Table 9.5 confirm or contradict your memory from organic chemistry ... 

Figure 2.19. Hydrogen abstraction transition states (TSs) for some model reactions. The structures for methane and allylic hydroxylation are taken from Ogliaro et alP- and De Visser et alP, the structure for H-abstraction from toluene from Ogliaro et alP, while for ethane hydroxylation from Yoshizawa et alP. Key geometric parameters outside parentheses correspond to the high-spin TS, while those within to the corresponding low-spin structure.

Styrene may be obtained from methane and toluene in addition to some other compounds [81] ... 

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