While considerable effort has been expended on determining the health effects of exposure to typical urban concentrations of O3, little is known about the chemical events responsible for toxicity. Phospholipids containing unsaturated fatty acids in the cell membranes of lung cells are likely reaction sites for inhaled ozone (O3). In this study, we examined the reaction of O3 with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) in unilamellar phospholipid vesicles. Reaction of ozone with the carbon-carbon double bond of POPC yielded an aldehyde and a hydroxy hydroperoxide. The hydroxy hydroperoxide eliminated H2O2 to yield a second aldehyde. Upon further ozonolysis, the aldehydes were oxidized to the corresponding carboxylic acids. A material balance showed that no other reaction consumed POPC and O3 or produced these products. As a mechanistic probe, we measured incorporation of oxygen-18 from 18O3 into aldehyde, carboxylic acid, and H2O2. Approximately 50% of the aldehyde oxygen atoms were derived from O3. Oxygen in H2O2 was derived solely from O3, where both oxygen atoms in a molecule of H2O2 were from the same molecule of O3. One of the carboxylic acid oxygen atoms was derived from the precursor aldehyde, while the other was derived from O3. These results support the following mechanism. Cleavage of the carbon-carbon double bond of POPC by O3 yields a carbonyl oxide and an aldehyde. Reaction of H2O with the carbonyl oxide yields a hydroxy hydroperoxide, preventing formation ozonide by reaction of the carbonyl oxide and aldehyde. Elimination of H2O2 from the hydroxy hydroperoxide yields a second aldehyde. Oxidation of the aldehydes by O3 yields carboxylic acids.

with TLC on silica gel with dimethylformamide (Rf 0.9) or aqueous 80% methanol (Rf 0.8). Attempted recrystallization usually resulted in partial decomposition, as shown by TLC. The analytical sample was dried for 9 h at 0.1 Torr at 100 °C. The compound darkened above 240 °C but did not melt up to 400 °C; 100-MHz !H NMR (Me2SO-d8) 8.55 (s, 1, NCHN), 8.10 (s, 1, CH=CB2), 7.64 (broadened s, 1, NH), 7.18 (broadened s, 1, NH), 3.42 (s, ~10, NH, BOH, and H20 from solvent); on addition of methanol dropwise, the 7.64 peak broadened, shifted downfield, and disappeared, and the 7.18 peak broadened somewhat without shifting; NMR (CD3OD)8.31 (brd s.

The method of Edwards and Roseveare has been used to study the interaction coefficients of the following gaseous mixtures at 30°: COr-Ni, Or-Ní, CO2-O2. _ An apparatus of improved design is described for making the measurements. The results give proof that the method is satisfactory for evaluation of the quantity [2Ba -(Bu + ¿22)], where 512 is the interaction coefficient and Bu and Ba are the individual second virial coefficients of the constituents of the mixture. Values of the interaction coefficients determined in this way for the CO2-N2 and O2-N2 systems agree satisfactorily with theoretical values based on simple combination rules for the force constants involved. The CO2-O2 results show a disagreement with the theoretical values which may be due to these combination rules.

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A laboratory-scale reactor was developed to evaluate the capture of carbon dioxide (CO 2 ) from a gas into a liquid as an approach to control greenhouse gases emitted from fixed sources. CO 2 at 5-50% concentrations was passed through a gas-exchange membrane and transferred into liquid media-tap water or simulated brine. When using water, capture efficiencies exceeded 50% and could be enhanced by adding base (e.g., sodium hydroxide) or the combination of base and carbonic anhydrase, a catalyst that speeds the conversion of CO 2 to carbonic acid. The transferred CO 2 formed ions, such as bicarbonate or carbonate, depending on the amount of base present. Adding precipitating cations, like Ca ϩϩ , produced insoluble carbonate salts. Simulated brine proved nearly as efficient as water in absorbing CO 2 , with less than a 6% reduction in CO 2 transferred. The CO 2 either dissolved into the brine or formed a mixture of gas and ions. If the chemistry was favorable, carbonate precipitate spontaneously formed. Energy expenditure of pumping brine up and down from subterranean depths was modeled. We conclude that using brine in a gas-exchange membrane system for capturing CO 2 from a gas stream to liquid is technically feasible and can be accomplished at a reasonable expenditure of energy.