Laboratory investigations of negative ion molecule reactions of propionic,butyric, glyoxylic, pyruvic, and pinonic acids

We have carried out laboratory measurements of gas-phase ion-molecule-react ions of several negative ion species with propionic, butyric, glyoxylic, py ruvic, and pinonic acids. A flow reactor operating at a temperature of 293 +/- 3 K and total gas pressures of 1.5 hPa, 9 hPa, or 40 hPa were used. The negative reagent ion species investigated included CO3-, CO3-H2O, NO3-, NO 3-H2O, NO2-, NO2-H2O and O-3(-). The reactions were found to proceed either via proton transfer, switching, or clustering. A new proton transfer chann el leading to alkylperoxy carboxylate radicals (R-H(OO .)COO-) was observed for propionic, butyric, and pinonic acids.(C) 2000 Elsevier Science B.V.