Salt with deuterium oxide

Bromine (7 ml) is added dropwise to a mixture of white sand (14 g) and red phosphorus (3 g, dried at 165° under vacuum) moistened with 5 ml of deuterium oxide. The apparatus is fitted with an exit tube to allow the liberated deuteriobromic acid to pass through two U-tubes and into a receiving flask. The first trap contains glass beads and is cooled in an ice-salt slurry. The second contains glass beads and red phosphorus moistened with deuterium oxide. The deuterium bromide gas is collected in the appropriate solvent at ice bath temperature. A small amount of phosphorus pentoxide should be added to remove any deuterium oxide if anhydrous reagent is required. 

The undeuterated salt was refluxed with deuterium oxide to effect deuterium exchange, then the excess was evaporated off under vacuum. Towards the end of the evaporation the moist residue exploded violently. The presence of D is not likely to affect instability of the structure. 

As a consequence, benzylic protons in a- and y-alkyl groups (but not in p-positions) are acidic and in water are in equilibrium with the corresponding methylenepyrans water at pH <5. Because the symmetric y-methylenepyrans (y-anhydrobases) are more stable than a-methylenepyrans [57], the isotopic exchange with deuterium oxide proceeds about ten times faster in y than in a, and this allows the synthesis of regiospecifically deuterated alkylpyrylium salts, which can then be converted into other deuterated compounds because the reaction with nucleophiles takes place even faster [58, 59],... 

Tricyclic derivatives of types 205, 248, and 270 contain an active methylene group attached to the carbon atom of the imine moiety. To determine the relative reactivity of the active methylene group, deuteration experiments with deuterium oxide were carried out on the hydrochloride salts of 95, 203, 283, 306, 375, and 376. The results were evaluated means of H-NMR spectroscopy. " The deuteration rates k were ... 

A cycloheptatrienide trianion would have ten ir-electrons and thus might be a stablised (4n+2) electron system. There is evidence for its formation in solution, when either hepta-1,3,6-triene or, more surprisingly, hepta-1,6-diene is treated with n-butyl lithium in tetramethylethylenediamine [390]. The lithium salt is apparently solvated by the amine. Its and n.m.r. spectra show singlets at 6 4.55 and 66.0, respectively. It reacts with deuterium oxide to give a mixture of trideuteriocycloheptadienes and with ethyl sulphate to give a mixture of triethylcycloheptadienes. 

The NMR spectrum shown in Figure 5 was obtained by dissolving hydralazine hydrochloride in deuterium oxide containing 3-(trimethylsilyl)-1-propane-sulfonic acid sodium salt (DSS). The series of peaks at 0, 0.6, 1.8, and 3 ppm are all due to the DSS. The peak at 4.8 ppm is due to HDO which forms on exchange with the solvent and the peaks at 8.01 and 8.61 ppm are due to the aromatic protons. The NMR spectrum of the base (Figure 6) was obtained in a 1 1 mixture of dimethylsulfoxide-d,- deuterochloroform. 

Fig. 5.9. 13Cf1 - NMR spectrum of flavin adenine dinucleotide (FAD), disodium salt, 30 mg in 1 ml, of deuterium oxide 30 °C 100.576/400.133 MHz (13C/ H) 5000 interferograms (32K/15000 Hz) (a) sp3 carbon partial spectrum (20-92 ppm) with expanded output (b) to display carbon-phosphorus couplings (2JCI, for A5 and R5 3Jcr for A4 and R4 carbon nuclei) (c) partial spectrum of heterocyclic carbon nuclei (117-167 ppm). Signals are assigned according to ref. [147].

Alkylation may take place either on sulfur or on oxygen to form either oxosulfonium or alkoxysulfonium salts. Whereas the former are useful in carbanion chemistry, the latter can be used in oxidizing reactions. If trimethylsulfoxonium iodide is heated with a mild base in deuterium oxide, the hydrogen atoms in the salt are replaced by deuterium. 

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