Hydrogen Abstraction from Hydrogen Sulfide Molecules by Methyl Radicals

Acetone has been photolyzed in the presence of the varied amounts of hydrogen sulfide in the temperature range from 50° to 140°C. From the analysis of the products at low conversions the initial rates of formation of carbon monoxide, methane and ethane have been determined, which, combined with the mechanism of acetone photolysis already established, give the values of k5/k31⁄2, where k5 and k3 are respectively the rate constants for the reactions CH3+H2S=CH4+HS and CH3+CH3=C2H6. Accepting k3=1013.38 mol−1 cc. sec−1 with zero activation energy as recommended by Shepp, the rate constant of the abstraction reaction is represented by k5=1011.4 exp (−2.6 kcal.mol−1/RT) mol−1 cc. sec−1.