The gas phase reactions of both S('D) and S(?P) atoms with propadiene afford methylenethiirane in nearly quantitative yields at high pressure. With 1,2-butadiene the three novel unsaturated isomeric thiirane products, resulting from addition to the 2,3 double bond and cis-and trans-addition to the 1,2 double bond, have been characterized. The yields are pressure and exposure-time dependent and, at zero conversion and high pressures, comprise -94% of the C4H,S adducts, the remainder being two thiol insertion products. The ratio of 2,3-addition to 1,2-addition is -1.3 for S('D) atoms and -2.1 for S(?P) atoms.Rate parameters for the S(") + 1.2-butadiene reaction were determined in competition with the S(?P) + I-C,H, reaction and found to be A = 6.4 + I. l X 10"' M -' s-' and E, = 1.4 + 0.2 kcal mol-'. The E,,'s associated with 1.
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