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The ethene−ozone reaction was investigated in a 570 L spherical glass reactor at atmospheric pressure, using long-path FTIR spectroscopy for detection of the individual products. Experiments were performed in the presence of hydroxy and carbonyl compounds to identify the reactions of the Criegee intermediate CH2OO formed in ethene ozonolysis. Using 13C-labeled HCHO, this reaction was found to proceed via an unstable cyclic adduct which decays to the detected products HCHO, HCOOH and CO. [CH2OO + HCHO → HCHO + HCOOH (eq 13); CH2OO + HCHO → HCHO + CO + H2O (eq 14a); CH2OO + HCHO → HCHO + HCO + OH (eq 14b)] The relative rates of the reactions of CH2OO with HCOOH and HCHO were determined from the product analysis. In addition, evidence was found that the reaction of CH3CHO with the CH2OO intermediate does not exclusively produce secondary propene ozonide, but also HCHO and CO2. The results of this study have been combined with data from previous investigations to give a complete description of the gas phase ozonolysis of ethene and are discussed in comparison with ozonolysis reactions occurring in the liquid phase.

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Ozonolysis of C2H4 was carried out at 295 K in 730 torr synthetic air in the concentration ranges of [O3]0 = 1.9–8.2 ppm and [C2H4]0 = 4.0–15.0 ppm, in the absence and presence of the added HCOOH (1 ppm), CH3COOH (1–10 ppm), and CH3OH (36–100 ppm). In the absence of the added compounds, a nearly complete analysis of the reaction products was achieved, with the yields expressed relative to the converted C2H4: HCHO 0.98, CO 0.26, CO2 0.18, HCOOH 0.05, and the sum of formic acid anhydride (FAN) and hydroperoxymethyl formate (HPMF), CHO(SINGLE BOND)O(SINGLE BOND)CH2OOH, 0.19. In the presence of the added HCOOH, the yield of [FAN + HPMF] increased. The addition of CH3COOH suppressed the formation of FAN and HPMF completely. The addition of large excesses of CH3OH also decreased the yield of [FAN + HPMF] significantly. In both cases, new products with the formula R(SINGLE BOND)O(SINGLE BOND)CH2OOH where R = CH3CO and CH3 for CH3COOH and CH3OH, respectively, were formed. The present results, together with the formation of hydroxymethyl hydroperoxide, HO(SINGLE BOND)CH2OOH, with added water vapor (Horie et al., Geophys. Res. Lett., 21, 1523, (1994)) were explained by the reaction of the Criegee biradical CH2OO with the added hydroxy compounds ROH. Formation of the products with the general formula R(SINGLE BOND)O(SINGLE BOND)CH2OOH indicates that the RO(SINGLE BOND)H bond fission has taken place. © 1996 John Wiley & Sons, Inc.

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