Mechanism of Reduction of Bis(2-hydroxyethyl) Trisulfide by eaq- and .CO2-. Spectrum and Scavenging of RSS. radicals

Article abstract of DOI:10.1021/j100219a029

Each of the of the reducing radicals e_aq^., .CO2^- and (CH3)2.COH cleaves bis(2-hydroxyethyl) trisulfide in aqueous solution to produce (2-hydroxyethyl)perthiyl (RSS.) radicals and 2-hydroxyethanethiol.The RSS. radical had λ_max = 374 nm, ε_max = 1630 +/- 50 M^-1cm^-1, and a second-order rate constant for dimerization 2k₁₂ = (1.4 +/- 0.3)*10⁹ M^-1s^-1 (2RSS. -> RS4R (12)).It is able to abstract H atoms from dihydroflavin adenine dinucleotide (FH2), but not from formate.Thus, in aqueous solution D_RSS-H must be greater than 60 but less than 90 kcal/mol.Although tetrasulfide and thiol are initial products of reduction, secondary thermal reactions occur and produce sulfanes (RS_nH) and polysulfides (RS_nR).In the early stages of reduction products of n = 2 dominate.However, on prolonged reaction with .CO2^- elemental sulfur precipitated, and this is probably formed by elimination from sulfanes with n much larger and in the region of 8.