Thiamine Derivatives of Disulfide Type. XIII. Kinetic Studies on the Degradation of Propyl Propanethiolsulfonate by Hydroxyl Ion

Abstract

Alkaline degradation of propyl propanethiolsulfonate (PrSSO₂Pr) was investigated to study the reaction mechanism for the synthesis of thiamine derivatives of disulfide type. It was postulated that PrSSO₂Pr degrades to thiolsulfinate (PrSSOPr) and sulfinic acid (PrSO₂H) eventually as shown in the following equations. PrSSO₂Pr+OH^-→PrSO₂^-+(PrSOH) 2(PrSOH)→^^(fast)PrSSOPr+H₂O The values of the enthalpy of activation and the entropy of activation were calculated to be 8.2 kcal/mole and -21.7 e. u. PrSSOPr underwent alkaline degradation as PrSSO₂Pr did, but the rate was rather smaller than that of PrSSO₂Pr.