The effect of the molecular structure of thiols on the mechanism of their radical scavenging

Experiments on H atom scavenging by alkanethiols in γ-irradiated aqueous solutions have confirmed that the reaction products depend on thiol structure. The percentage of H abstraction decreases with increasing branching at the carbon atom α to sulfur while -SH abstraction simultaneously increases. Methyl and ethyl radicals appear to react only by H abstraction from the thiol group since the yields of methane and ethane are independent of thiol structure. There is no significant temperature dependence of the H₂ and H₂S yields over the range 0–50°C for aqueous solutions of cysteine and penicillamine.