Kinetic study of the stability of (NH2)2CSSC(NH2)22+
The kinetics of the decomposition of formamidine disulfide dihydrochloride, (NH2)2CSSC(NH2)22+ 2Cl–, in aqueous solution at 25 °C are general base catalysed, and rate constants have been measured over the pH range 1.91–9.03. Analysis of the data yields ionisation constants pK1= 5.49, pK2= 7.66 and rate constants for deprotonation of the substrate by OH– and H2O. For the doubly charged cation, reaction occurs through a small concentration of a reactive tautomer, (HN)(NH3+)CSSC+(NH2)2, which is attacked by H2O. The singly charged cation reacts by parallel pathways involving OH– and H2O as attacking bases.