Reactions of the nitrate radical with a series of reduced organic sulphur compounds in air

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 3 CH 2 SH, (CH 3 CH 2 ) 2 S, (CH 3 CH 2 ) 2 S 2 , and CH 3 CH 2 SCH 3 in air. The products CH 3 CH 2 SO 3 H, SO 2 , H 2 SO 4 , CH 3 CHO, and CH 3 CH 2 ONO 2 were identified and quantified in the reactions of the first three compounds, CH 3 CH 2 SH, (CH 3 CH 2 ) 2 S, and (CH 3 CH 2 ) 2 S 2 . The reaction products were CH 3 CH 2 SO 3 H, CH 3 SO 3 H, SO 2 , H 2 SO 4 , CH 3 CHO, and CH 2 O in the reaction of CH 3 CH 2 SCH 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 3 SCH 3 , CH 3 SH, and CH 3 SSCH 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 2 SO 4 , RSO 3 H, RCHO, and RCH 2 ONO 2 , as the main reaction products. The inital step of the reaction of NO 3 with RSR and RSH type (R = CH 3 , CH 2 CH 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 RSSR type compounds, evidence for an addition‐decomposition reaction, as the initial steps, was obtained. RS·, RS(O)·, and RS(O) 2 · appear to be formed as intermediates in all the reactions. © John Wiley & Sons, Inc.