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 alk yl 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) molecu le(-1) s(-1) for the reaction of Cl with n-butane, the following value s for the reaction-rate coefficients were determined in the presence o f nitrogen (in units of 10(-10) cm(3) molecule(-1) s(-1)) to be: dimet hyl sulfide, 3.61 +/- 0.21; ethylmethyl sulfide, 4.89 +/- 0.29; diethy l sulfide, 5.98 +/- 0.23; and dipropyl sulfide, 7.02 +/- 0.81. The rel ative-rate experiments were conducted in an atmosphere of either nitro gen or synthetic air to investigate the effect of the presence of oxyg en on the rate coefficient; only the rate coefficient for the reaction of Cl with dimethyl sulfide showed an appreciable difference, yieldin g a value of (4.19 +/- 0.16) x 10(-10) cm(3) molecule(-1) s(-1). Furth er experiments were undertaken to measure the relative-rate coefficien ts of the series of alkyl sulfides using cyclohexane as the reference compound. In most cases, the value of k(sulfide)/k(n-butane) divided b y the value of k(sulfide)/k(cyclohexane) produced a value of k(cyclohe xane)/k(n-butane), consistent with our experimentally determined value of k(cyclohexane)/k(n-butane) = 1.69 +/- 0.04. The results are discus sed with respect to the literature data, structure activity relationsh ips, chemical mechanisms and the chemistry of the marine atmosphere.