A 480 L evacuable reaction chamber, equipped with FT-IR spectroscopy on-line and ion chromatography off-line, has been used to study the gas phase reaction between the nitrate radical, NO
3, and the reduced organic sulphur compounds CH
3CH
2SH, (CH
3CH
2)
2S, (CH
3CH
2)
2S
2, and CH
3CH
2SCH
3 in air. The products CH
3CH
2SO
3H, SO
2, H
2SO
4, CH
3CHO, and CH
3CH
2ONO
2 were identified and quantified in the reactions of the first three compounds, CH
3CH
2SH, (CH
3CH
2)
2S, and (CH
3CH
2)
2S
2. The reaction products were CH
3CH
2SO
3H, CH
3SO
3H, SO
2, H
2SO
4, CH
3CHO, and CH
2O in the reaction of CH
3CH
2SCH
3. On the basis of identified reaction products and intermediates observed in the infrared spectra, mechanisms are proposed for the reactions between the NO
3 radical and the four reduced organic sulphur compounds. The results of this study, together with those from previous experiments performed in this laboratory on CH
3SCH
3, CH
3SH, and CH
3SSCH
3 lead to the conclusion that all these species, in the reaction with the NO
3 radical, follow a similar degradation mechanism producing SO
2, H
2SO
4, R? SO
3H, R? CHO, and R? CH
2ONO
2, as the main reaction products. The inital step of the reaction of NO
3 with R? S? R and R? S? H type (R = CH
3, CH
2CH
3) reduced organic sulphur compounds was found to be H-atom abstraction, probably after the formation of an initial adduct. For the reaction between NO
3 and R? S? S? R type compounds, evidence for an addition-decomposition reaction, as the initial steps, was obtained. R? S·, R? S(O)·, and R? S(O)
2· appear to be formed as intermediates in all the reactions. © John Wiley & Sons, Inc.
相似文献