Deutero benzene

Polymer Characterization. Proton NMR spectra at 300 MHz were obtained from a Varian HR-300 NMR spectrometer. Deutero-benzene and spectrograde carbon tetrachloride were used as solvents. The concentration of the polymer solutions was about 1-5%, Carbon-13 NMR spectra were obtained from a Varian CFT-20 NMR spectrometer, using deuterochloroform as the solvent for the polymers. The concentration of the solutions was about 5%. Chemical shifts in both proton and carbon-13 spectra were measured in ppm with respect to reference tetramethylsilane (TMS). All spectra were recorded at ambient temperature. 

The amounts of the various deutero-benzenes and deutero-cyclohex-anes formed during the course of reaction between benzene and deuterium on a number of evaporated metallic films have been followed by a mass-spectrometric technique. The most extensive results were obtained over platinum and palladium films because both the exchange reaction and the deuteration reaction were found to occur simultaneously on these metals, but some results were also obtained with nickel, tungsten, iron, and silver films. 

The amounts of the various deutero-benzenes and deutero-cyclohexanes formed during the course of typical experiment are given in Table I. The detailed results are most easily discussed under a series of headings. 

C. Kemball The Queen s University of Belfast) The mechanism that Professor Burwell has just su ested for the deuteration of benzene may well be correct, since it provides a good explanation of the absence of redistribution. We have no evidence to show whether the six deuterium atoms are added singly or in pairs to the benzene molecule. A substantial difference between the benzene-deuterium system and the ethylene-deuterium system is that the adsorbed radical CeHeD cannot readily lead to deutero-benzenes, whereas the adsorbed C2H4D radical is almost certainly a vital intermediate in the formation of deutero-ethylenes. 

Although heavy water has been mentioned throughout this description as the deuterium compound employed 70 for the moderator, it is recognized that other compounds of deuterium will also be satisfactory, and for example, as deutero carbons such as deutero diphenyl and deutero benzene. 

Another possibility for the comparison of the acid strength of different hydroxyl groups has been proposed, using kinetic data such as the rate of hydrogen-deuterium exchange followed by time-resolved IR spectroscopy, as has been shown upon adsorption of deutero benzene in dealuminated zeolites Y [45j. 

X, Y, Z are mole fractions of benzene-do, deuterobenzene, and deutero-cyclohexane in the hydrocarbons leaving the reactor (X Y Z = 1) ... 

Fig. 5.7 Excess pressures of equimolar solutions of per-protio and per-deuterobenzene and of per-protio and/ter-deuterocyclohexane. AP = (Psolution-[0.5P°(per — protio) + 0.5P°(/ er — deutero]). The upper line refers to cyclohexane (C6H12/C6D12) solutions, the lower to benzene (CeHe/CgDg) (Redrawn with permission from Jakli, Gy., Tzias, P., and Van Hook, W. A. J. Chem. Phys. 68, 3177 (1978). Copyright 1978, American Institute of Physics)...

The 5-deutero and 4,6-dideutero derivatives of 1,2,3-trimethoxy-benzene were prepared by methylating the corresponding deuterated 2,6-dimethoxyphenols with dimethyl sulfate in 10% NaOH at room temperature. 

Complete analyses of the various deutero-ethylenes and deutero-ethanes were first obtained by Turkevich et at. (4), using a nickel wire, and this type of information has since been reported by Wilson et al. 5) for a bulk nickel catalyst and by Kemball 6) for a series of evaporated metallic films. In all cases, the ethanes produced range over the complete spectrum from do-ethane to do-ethane, and Kemball showed that it is possible to correlate the nature and the amount of the deutero-ethylenes formed over metallic films with the distribution of deuterium in the ethanes. Although the detailed mechanisms of the exchange and deuteration of ethylene are still the subject of controversy, it is clear that both are closely related and both involve the half-hydrogenated state, i.e., the adsorbed ethyl radical, as an intermediate. The main objective of the present research was to extend such studies to the benzene-deuterium system. 

Isomerization of l-deutero-l,3-dimethylindine at 30°C in pyridine,benzene, and methanol, using DABCO as catalyst, occurs with relative rates of 6.5, 1.14, and 1.0 respectively24 . The low relative rate in methanol is probably due to hydrogen bonding between the solvent and catalyst. The relative rates in the two aprotic solvents decrease in order of the decreasing dielectric constants of the solvents. 

From a stereochemical point of view, Dauben reported the bromination of enriched a-deutero-ethyl benzene (41) and showed it to be totally non-selective. This suggests that without other mitigating circumstances, the radical is flat. 

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