Rate coefficients for the room temperature reaction of Cl atoms with dimethyl sulfide and related alkyl sulfides

Rate coefficients for the reaction of Cl atoms with a selection of alkyl sulfides have been determined using the relative rate technique at 298 +/- 3 K. Based on an absolute value of 1.94 x 10(-10) cm(3) molecule(-1) s(-1) for the reaction of Cl with n-butane, the following values for the reaction-rate coefficients were determined in the presence of nitrogen (in units of 10(-10) cm(3) molecule(-1) s(-1)) to be: dimethyl sulfide, 3.61 +/- 0.21; ethylmethyl sulfide, 4.89 +/- 0.29; diethyl sulfide, 5.98 +/- 0.23; and dipropyl sulfide, 7.02 +/- 0.81. The relative-rate experiments were conducted in an atmosphere of either nitrogen or synthetic air to investigate the effect of the presence of oxygen on the rate coefficient; only the rate coefficient for the reaction of Cl with dimethyl sulfide showed an appreciable difference, yielding a value of (4.19 +/- 0.16) x 10(-10) cm(3) molecule(-1) s(-1). Further experiments were undertaken to measure the relative-rate coefficients of the series of alkyl sulfides using cyclohexane as the reference compound. In most cases, the value of k(sulfide)/k(n-butane) divided by the value of k(sulfide)/k(cyclohexane) produced a value of k(cyclohexane)/k(n-butane), consistent with our experimentally determined value of k(cyclohexane)/k(n-butane) = 1.69 +/- 0.04. The results are discussed with respect to the literature data, structure activity relationships, chemical mechanisms and the chemistry of the marine atmosphere.