Concerted Solvent Processes for Common Sulfonyl Chloride Precursors used in the Synthesis of Sulfonamide-based Drugs

Specific rates of solvolysis in hydroxylic solvents available for the solvolysis of 2-thiophenesulfonyl chloride and phenylmethanesulfonyl chloride are supplemented by determining the values in fluoroalcohol-containing solvents. The data sets are then correlated using the extended Grunwald-Winstein equation. For both substrates, it is found that a single correlation controls the influence of solvent over the full range of solvent composition. The sensitivities to solvent nucleophilicity and solvent ionizing power are compared to values available for other substrates. Three of these previous studies are upgraded by the incorporation of additional specific rate values from the recent literature. With a methyl, isopropyl, benzyl, aromatic or heteroaromatic group as the R group of RSO(2)Cl, a concerted S(N)2 mechanism is proposed for the solvolysis.