A Detailed Study of Sulfonate Ester Formation and Solvolysis Reaction Rates and Application toward Establishing Sulfonate Ester Control in Pharmaceutical Manufacturing Processes

Sulfonate esters of lower alcohols possess the capacity to react with DNA and cause mutagenic events, which in turn may be cancer inducing. Consequently, the control of residues of such substances in products that may be ingested by man (in food or pharmaceuticals) is of importance to both pharmaceutical producers and to regulatory agencies. Given that a detailed study of sulfonate ester reaction dynamics (mechanism, rates, and equilibria) has not been published to date, a detailed kinetic and mechanistic study was undertaken and is reported herein as a follow-up to our earlier communication in this journal. The study definitively demonstrates that sulfonate esters cannot form even at trace level if any acid present is neutralized with even the slightest excess of base. A key conclusion from this work is that the high level of regulatory concern over the potential presence of sulfonate esters in API sulfonate salts is largely unwarranted and that sulfonate salts should not be shunned by innovator pharmace...