Effect of Deuterium Oxide

Rates of hydrolysis of several substrates in water and in D20 have been compared (9). Average values of Vh2o/Vd2o were, for glutamine, 1.16 for methyl glutamate, 1.38 for glutamyl methylamide, 1.10 and for glutamic acid, 1.50. 

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Effect of Deuterium Oxide on Protein Aggregation in Deuterio and Protio Phycocyanin and Other Proteins... 

Effect of Deuterium Oxide and Water on Mutarotation Reactions. 31... 

P. Camilleri et al.. Effect of deuterium oxide on the resolution of the optical isomers of ibuprofen on an alpha-l-acid glycoprotein column J. Chromatogr., 518(1990)277. 

Sailer, B. L. Nastasi, A. J. Valdez, J. G. Steinkamp, J. A. Crissman, H. A. Differential effects of deuterium oxide on the fluorescence lifetimes and intensities of dyes with different modes of binding to DNA. J. Histochem. Cytochem. 1997, 45, 165-175. 

The spectrum of a solution in deuterochloroform (Fig. 3.65) shows three absorptions at <5 4.5, 5.08 and 7.3 with an intensity ratio of 2 1 5. The effect of adding a few drops of deuterium oxide to the sample tube and shaking vigorously is shown in the re-recorded spectrum (Fig. 3.66). The absorption at S 5.08 in the original spectrum which disappears on deuteration is clearly due to the hydroxyl proton. 

The use of deuterium oxide as D source under the action of Pd/C ad catalyst is shown in Scheme 3. The catalyst was prepared from 10% Pd on charcoal and H2 gas and shown to be effective for H-D exchange on benzylic carbon [11a]. 

Studies of anhydro-8-hydroxy-2,3-dihydrothiazolo[3,2-a]pyridinium hydroxide systems show that selective deuterations can be achieved. Thus the 5-methyl group in (473) can be selectively deuterated via its anhydro base, the difficulty being to avoid deuteration at C-3. A proton at C-5 (474) is exchanged under mild alkaline conditions. Deuteration at C-3 is best effected via the 3-carboxy derivative (475) which readily exchanges the remaining H-3 and is subsequently decarboxylated in the presence of deuterium oxide. Deuteration at C-2, which is the least reactive position, is best carried out before cyclization <8lH(l5) 1349). 

The mixtures showed broadened absorption spectra compared to those of individual spectra indicating the formation of aggregate due to the electrostatic attractions between the cationic and anionic porphyrins. The size of the aggregate were expected larger than 5 x lO m since the filtrated solution from a membrane filter showed neither absorption nor. photoactivity. Use of deuterium oxide or heavy water as solvent had no effect on the emission intensities suggesting involvement of singlet oxygen is unlikely in this process. 

Warshel, a., Bromberg, A., Oxidation of 4a,4b-Dihydrophenanthrenes. III. A Theoretical Study of the Large Kinetic Isotope Effects of Deuterium in the Initiation Step of the Thermal Reaction With Oxygen, J. Chem. Phys. 1970, 52, 1262. 

Supportive of the suggestion that ionization is not a major pathway in the Claisen rearrangement of the parent compound is the fact that the SDKIEs in aqueous solution are comparable to those in the gas phase and in m-xylene. Furthermore, attempts to solvolyze 1,1-dideuterioaUyl mesylate in aqueous methanol resulted in no ionization to an allyl cation instead, the direct displacement product was formed exclusively. Finally, determinations of a solvent kinetic isotope effect in deuterium oxide resulted in values around unity 10%. ° In the solvolysis reaction of tert-butyl chloride the value is 40% at room temperature. " It is possible to cause allylvinyl ethers to ionize by providing cation stabilizing substituents and Lewis acids or Lewis acidic solvents. ... 

Effect of Impurities on the Critical Solution Temperature. The addition of even a small amount of a third component to a two-liquid system will ordinarily alter the C.S.T. considerably. Thus, for example, the addition of 0.2 per cent of water to glacial acetic acid raises the C.S.T. with cyclohexane from 4.2 to approximately 8.2 C. Useful methods of analysis have been devised based on such observations. For example, the amount of deuterium oxide in water can be estimated by measuring the C.S.T. with phenol and the aromatic hydrocarbon content of petroleum fractions by the C.S.T. with aniline. In general, the C.S.T. will be raised if the added component is highly soluble in only one of the original components (salting out) and lowered if it is highly soluble in both. Such systems properly must be considered as three-component mixtures, however. 

The most important piece of evidence for proton transfer in enzymatic systems comes from the application of deuterium oxide kinetic solvent isotope effects. If the enzymatic rate-limiting step involves a proton transfer in the transition state, a solvent isotope effect ( hjoAdzo) of 2 to 3 is observed, in good agreement with values observed in non-enzymatic proton transfer reactions [13]. The... 

The physical and thermodynamic properties of elemental hydrogen and deuterium and of their respective oxides illustrate the effect of isotopic mass differences. 

Complete exchange of protons in a sterically unhindered position a to a carbonyl group can be achieved by heating a solution of the ketone in O-deuterated solvents in the presence of an acid or base catalyst, the latter being the more effective. The most commonly used solvents are methanol-OD, ethanol-OD, and the aprotic solvent anhydrous tetrahydrofuran or dioxane mixed with deuterium oxide. Under alkaline conditions the exchange rate in 153 2 14,164 stcroids, for example, is usually... 

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