73891-30-2Relevant academic research and scientific papers
Effect of Charged Substituents on Rates of the Thiol-Disulfide Interchange Reaction
Hupe, D. J.,Wu, Dorothy
, p. 3100 - 3103 (2007/10/02)
Rate constants in aqueous solution at 25 deg C are reported for the production of p-nitrothiophenol from the mixed disulfides RSSC6H4NO2 upon reaction with the thiol anions R'S-.The R' groups used varied in charge and include -O2CCH2CH2, +H3NCH2CH2, and HOCH2CH2.The R groups used were these same three in addition to -O2CCH2CH2CH2.The solutions of RSSC6H4NO2 were prepared by allowing O2NC6H4S- to react with an excess of RSSR, followed by rapidly mixing R'S- and measuring the return of the absorption due to O2NC6H4S-.The rates for reactions involvingcharged R and R' groups differ from those with uncharged groups of identical pKa by factors of up to 2.5.Negatively charged groups, especially on the central thiol, slow the reaction and positively charged groups speed the reaction to a greater extent than that predicted by the calibrating ionization reaction.Ramifications of these observations are considered for the prediction of rate constants of thiol-disulfide interchange reactions and for the interpretation of β values when reactants of various charge types are used.
