Reaction of hydrogen atoms with diethyldisulfide and ethylmethyldisulfide

H atoms react with C 2 H 5 SSC 2 H 5 to give C 2 H 5 SH as the sole retrievable product with ϕ = 2.32 at 25°C and 2.84 at 145°C. The primary reaction is postulated to be H + C 2 H 5 SSC 2 H 5 ← C 2 H 5 SH + C 2 H 5 S with k 1 = (4.73 ± 0.64) × 10 13 exp [−(1710 ± 69)/ RT ] cm 3 /mol·s relative to the rate constant of the H + C 2 H 4 ← C 2 H 5 reaction. The high value of the entropy of activation suggests the presence of partial hydrogen bonding in diethyldisulfide which is broken in the transition state. Ethylmethyldisulfide reacts similarly: H + C 2 H 5 SSCH 3 ← C 2 H 5 SH + CH 3 S or CH 3 SH + C 2 H 5 S. The thiyl radicals propagate a chain of radical exchange reactions forming the symmetrical disulfides with exposure‐time‐dependent quantum yields. The overall kinetics conform to a 16‐step mechanism from which the rate constants of the elementary reactions could be established by computer modeling. Thiyl radicals react considerably more slowly with disulfides than H atoms.