Carbon dioxide isotope exchange reactions

Halas S, Wolacewicz W (1982) The experimental study of oxygen isotope exchange reaction between dissolved bicarbonate and water. J Chem Phys 76 5470-5472 Halas S, Szaran J, Niezgoda H (1997) Experimental determination of carbon isotope equilibrium fractionation between dissolved carbonate and carbon dioxide. Geochim. Cosmochim. Acta 61 2691-2695... 

Brandner JD, Urey MC (1945) Kinetics of the isotopic exchange reaction between carbon monoxide and carbon dioxide. J ChemPhys 13 351-362... 

By means of the isotopic exchange reaction between uranium dioxide powders with a normal content, and carbon dioxide gas enriched in 1 0, the self-diffusion of oxygen in the stoichiometric and non-stoichiometric dioxide was measured. For essentially stoichiometric UO2, the diffusion of oxygen at 550 to 780C was... 

Katakis and Taube examined the reactions of mixtures of ozone and carbon dioxide irradiated by ultraviolet light, using isotopically labeled reactants to ascertain the mechanism. They found an isotopic exchange to occur between O3 and CO2, and concluded that 0( D) was the intermediate which was responsible. They did not find CO as a product, and thus they felt that reaction (11) was not important in their system, but that exchange occurred via... 

Isotopic exchange of H-5 occurs in the enzymic oxidation of UDP-D-glucose to the D-glucuronic acid analogue, which is explained by enolization of an intermediate aldehydo-species. Study of the acid-catalysed decarboxylation of penturonic, hexuronic, and hepturonic acids showed that the first two gave one equivalent of carbon dioxide nearly qualitatively, which was not the case with the hepturonic compounds. Derivatives of such hepturonic acids have been prepared by application of the Ivanov reaction as outlined in Scheme 4. ... 

It then becomes incorporated into molecules of carbon dioxide by reaction with oxygen or by exchange with stable carbon isotopes in molecules of carbon dioxide or monoxide. Molecules of COa mix rapidly into the atmosphere and hydrosphere as well as living organisms to attain a constant level of concentration representing a steady-state equilibrium maintained because of the continuous production of and its on-going radioactive decay hence. 

Carbon.— The use of isotopes in studies of the mechanisms of reactions of carbon dioxide or carbonates has been reviewed. Measurements using and give a rate constant of 1141 mol s" for the exchange reaction between carbon dioxide and carbonate ion at 25 °C the same techniques have been applied to the bovine carbonic anhydrase-catalysed exchange between carbon dioxide, its related species, and water.The decomposition rates of the alkyl monocarbonates in aqueous alkali and the effect of polyelectrolytes on the conversion of ammonium cyanate into urea have been reported. The application of calculations originally used for 5 b2 processes to the classical Sn2 halide ion-alkyl halide exchange reaction accounts quantitatively for the relative reactivities in terms of steric effects alone it is not necessary to invoke polar effects. Some further evidence for ion-pair intermediates in Sn2 substitutions has been obtained. ... 

Chemical exchange methods for the separation of isotopes utilise the small differences of concentration that exist at equilibrium in a reversible reaction involving two chemical substances. As a method of enriching carbon-13, it was discovered that the formation of salt-type carbamates (2) when carbon dioxide combines with amines (1) in non-aqueous solutions (Equation 2) fulfilled the desired conditions [30—32]. Oxygen-18 enrichment occurred in the gaseous carbon dioxide and carbon-13 in the carbamate (2). The emiched carbamate readily... 

Carbonate salts and many organic compounds form carbon dioxide on heating. Carboxylic acids can be converted to the silver salt by adding silver nitrate to the aqueous solution and then neutralizing with ammonia or any other base (Bentley, 1949a). The precipitated silver salt is filtered or centrifuged, washed, dried, and pyrolyzed to COj at 400 C. The silver salts can also be decarboxylated by treatment with bromine in carbon tetrachloride (the Hunsdiecker reaction). In all cases decarboxylation must be carried out in a water-free environment to avoid isotopic dilution by exchange. 

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