Temperature-dependent kinetics studies of aqueous phase reactions of hydroxyl radicals with dimethylsulfoxide, dimethylsulfone, and methanesulfonate

Abstract

A laser flash photolysis -long path UV-visible absorption -competitive kinetics technique has been employed to investigate the kinetics of the aqueous phase reactions between the hydroxyl radical (OH) and three organic sulfur species of atmospheric interest, dimethylsulfoxide (DMSO; CH 3 S(O)CH 3 ), dimethylsulfone (DMSO2; CH 3 (O)S(O)CH 3 ), and methanesulfonate (MS; CH 3 (O)S(O)O -). Thiocyanate anion (SCN -) has been employed as the competitor. Temperature dependent rate coefficients for the reactions of interest are reported for the first time. The following Arrhenius expressions adequately summarize the kinetic data obtained over the temperature range 275 -310 K (units are M -1 s -1 ): ln k DMSO = Aquat. Sci. 65 (2003) 425-435 Aquatic Sciences (26.88 ± 0.14) -{(1270 ± 40)/T}; ln k DMSO2 ≤ (22.36 ± 0.17) -{(1690 ± 50)/T}; ln k MS = (25.20 ± 0.13) -{(2630 ± 40)/T}. Uncertainties in the Arrhenius parameters are 2s and represent precision only. The accuracies of individual measured rate coefficient ratios, k X (T)/k SCN -(T) (X = DMSO, DMSO2, or MS), are estimated to be ±5% independent of T and the identity of X. Taking uncertainties in k SCN -(T) into account, we estimate the absolute accuracy of reported rate coefficients to be 16 % at 275 K, 9 % at 295 K, and 12 % at 310 K. The implications of the new kinetics results for understanding the atmospheric sulfur cycle are discussed.

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

“…Therefore, these values were also excluded for the averaging. The averaged rate constant obtained of k 2,aver = 1.13 10 10 m À1 s À1 confirms the selected value from Buxton [3] and fits well into the averaged temperature dependency from Zhu et al [31] ( Figure 3).…”

“…Finally, in the studies of Bardouki et al [30] and Zhu et al, [31] aqueous phase reaction data of interest for the atmospheric multiphase oxidation of dimethyl sulfide (DMS) are available. In this substance group there are eleven new determinations and seventeen remeasurements, most of which are in reasonable agreement with the formerly available measurements (class 2A) with the exception of the measurement of the reaction of OH with methylglyoxal, indexed as 2B and to be discussed in the following (see Table 3).…”

“…Zhu et al [31] averaged the temperature-dependent rate constants from two studies [62,63] and applied the mean values in their study (Figure 3). Both studies were weighted equally with the exception that the values at the highest temperatures (T = 352 K) from Elliot and Simsons [63] were not included.…”

“…Both studies were weighted equally with the exception that the values at the highest temperatures (T = 352 K) from Elliot and Simsons [63] were not included. Since the temperature dependency of R2 was not further investigated in the last years the mean temperature dependency calculated by Zhu in 2003 [31] is still valid. However, as can be seen in Figure 3, if one applies the temperature dependency from Zhu [31] , from Chin and Wine [62] or from Elliot and Simsons, [63] it will not affect the results strongly.…”

Anthropogenic contributions to global carbonyl sulfide, carbon disulfide and organosulfides fluxes

“…Oxidation of DMS at lower temperatures can lead to increasing amounts of organic products, although these are always smaller than SO 2 ; methylsulfinic acid being the largest along with smaller quantities of DMSO and MSA (Karl et al, 2007). The transformation of DMS leads to a wider range of organic and inorganic sulfur species, mainly SO 4 2-, SO 2 , OCS, methanesulfinic acid and MSA (Hatakeyama et al, 1982;Panter and Penzhorn, 1980;Pham et al, 1995;Faloona, 2009), with dimethylsulfone and dimethylsulfoxide as potential products (Harvey and Lang, 1986;Zhu et al, 2003). The small fraction of DMS converted to MSA is extremely soluble in the aerosol phase (Clegg and Brimblecombe, 1985).…”