Evidence for Hypervalent Intermediates in Acid Hydrolysis of Sulfinamide. 18O Exchange and a Break in pH-Rate Profile

NMR Detection and Study of Hydrolysis of HNO-Derived Sulfinamides

“…Sulfinamides are known to undergo hydrolysis to form sulfinic acids, especially under acidic conditions. ,,− We have previously observed the slow conversion of primary sulfinamides to their corresponding sulfinic acids and have now explored this reactivity using the 15 N-edited 1 H NMR method.…”

“…At physiological pH and temperature, the major reactions of sulfinamides involve the reduction to free thiols in the presence of excess thiol and hydrolysis to form sulfinic acids. , There are very few studies on the hydrolysis of sulfinamides, the majority of which have been carried out under aqueous, acidic conditions. − The mechanism is thought to involve a sulfurane intermediate (Scheme ) . Studies conducted with several N-substituted alkyl sulfinamides indicate that aliphatic secondary sulfinamides are relatively stable at basic pH, but hydrolysis can proceed readily at pH 3. , Also, tertiary sulfinamides have been found to be more reactive than secondary sulfinamides .…”

Evidence for Existence of Intermediate in Acid Hydrolyses of Sulfinamide and Carboxamide

“…This suggestion implies that the protonation at the sulfinyl oxygen atom should be more favorable than that at the N-3 atom of N-benzenesulfinyl benzimidazole, which is in accord with our observation of the 18 O-leveled structure in the hydrolyses of benzenesulfinamide derivatives. 2 Likewise, the mechanism for acid hydrolysis of N-benzoyl benzimidazole should be similar to the one proposed in acid hydrolysis of sulfinamide, i.e., acid hydrolysis of carboxamide should proceed through a terahedral intermediate.…”

“…In previous work, acid catalyzed hydrolysis of primary sulfinamides was reported by the authors. 2 Herein, acid catalyzed hydrolysis of sulfinamides involving electrondonating substituent in the aniline leaving group exhibited downward breaks for variation of the pH values. The results provided the first unequivocal evidence that nucleophilic substitution reaction at the sulfinyl sulfur may proceed through a two-step mechanism involving a hypervalent reaction intermediate.…”

Evidence for Hypervalent Intermediate in Aminolysis Reaction of Ethylbenzene Sulfinate

“…These observations were successful in the hydrolysis of sulfinate ester 6 and sulfinamides. 7 However, it is still to be clarified whether the simple nucleophlic substitution reactions at sulfur atom take place through a sulfurane.…”