Deuterium methane

The production of hot radicals and molecules by chemical reaction was recognized by early workers.4 Two important instances were the deuterium-methane exchange mechanism of Taylor and co-workers,5 and the atomic-cracking degradation reaction of hydrocarbons, suggested by Steacie and co-workers.2 Equation (I), in which one of the radicals, Ri and R2, may be a hydrogen atom, generalizes the possibilities in these two processes ... 

VISCOSITY OF HYDROGEN, DEUTERIUM, METHANE, AND CARBON MONOXIDE FROM -50 TO 150 C BELOW 200 ATMOSPHERES. 

Protonated methanes and their homologues and derivatives are experimentally indicated in superacidic chemistry by hydrogen-deuterium exchange experiments, as well as by core electron (ESCA) spectroscopy of their frozen matrixes. Some of their derivatives could even be isolated as crystalline compounds. In recent years, Schmidbaur has pre-... 

The di-7r-methane rearrangement has been studied in a sufficient number of cases to develop some of the patterns regarding substituent effects. When the central sf carbon is unsubstituted, the di-7i-methane mechanism becomes less favorable. The case of 1,1,5,5-tetraphenyl-l,4-pentadiene is illustrative. Although one of the products has the expected structure for a product of the di-7t-methane rearrangement, labeling with deuterium proves that an alternative mechanism operates ... 

The photo-Kolbe reaction is the decarboxylation of carboxylic acids at tow voltage under irradiation at semiconductor anodes (TiO ), that are partially doped with metals, e.g. platinum [343, 344]. On semiconductor powders the dominant product is a hydrocarbon by substitution of the carboxylate group for hydrogen (Eq. 41), whereas on an n-TiOj single crystal in the oxidation of acetic acid the formation of ethane besides methane could be observed [345, 346]. Dependent on the kind of semiconductor, the adsorbed metal, and the pH of the solution the extent of alkyl coupling versus reduction to the hydrocarbon can be controlled to some extent [346]. The intermediacy of alkyl radicals has been demonstrated by ESR-spectroscopy [347], that of the alkyl anion by deuterium incorporation [344]. With vicinal diacids the mono- or bisdecarboxylation can be controlled by the light flux [348]. Adipic acid yielded butane [349] with levulinic acid the products of decarboxylation, methyl ethyl-... 

Fur die Reaktion zwischen Methan und Deuterium sind zwei Mecha-nismen vorgeschlagen worden. 

Coillet, D. W., and G. M. Harris Exchange Reactions of Methane and Monodeuteromethane with Atomic Deuterium. J. Amer. chem. Soc. 75, I486 (1953.). 

The complex TpPtMeH2 was synthesized by reacting TpPtMe(CO) with water (66). While it is stable towards reductive elimination of methane at 55 °C, deuterium incorporation from methanol-c/4 solvent occurs rapidly into the hydride positions and subsequently, more slowly, into the methyl position (Scheme 15). The scrambling into the methyl position has been attributed to reversible formation of a methane complex which does not lose methane under the reaction conditions (75,76). Similar scrambling reactions have been observed for other metal alkyl hydrides at temperatures below those where alkane reductive elimination becomes dominant (77-84). This includes examples of scrambling without methane loss at elevated temperature (78). 

In a bimolecular reaction, at least two bonds change simultaneously. Figure 22.4 shows how bond orders and valences change in the reaction of methane with a H atom (shown in the deuterium-labeled form that can be studied experimentally)... 

Utiyama, M. Hattori, H. Tanabe, K. Exchange reaction of methane with deuterium over solid base catalysts. J. Catal. 1978, 53, 237-242. 

Fio. 20. Geometrical relationships for the simple exchange of methane with deuterium involving adjacent surface atoms each of which has available two octahedral bonding directions suitable for the reaction. 

Table 11.13 Deuterium fractionation in the water-hydrogen-methane system, after Bottinga (1969) (wv = water vapor, me = methane, hy = hydrogen).

Many mechanistic implications have been discussed, but we will concentrate here only on the most important structures in the context of dihydrogen-cation complexes. Deuterium-labeled methane and methyl cations were employed to examine the scrambling and dissociation mechanisms. The protonated ethane decomposition yields the ethyl cation and dihydrogen. Under the assumption that the extra proton is associated with one carbon only, a kinetic model was devised to explain the experimental findings, such as H/D scrambling. ... 

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