I've come across some scientific literature (e.g., https://doi.org/10.1021/jm400751p) that notably feature 1-propanesulfonyl chloride (PsCl) in the selective activation of hydroxy groups, such as a primary alcohol at the expense of a secondary one. Since tosyl chloride (TsCl) is so much more commonly used than structural homologues of mesyl chloride (MsCl) in general alcohol activation, this has prompted me to wonder: Starting from and explaining with organic chemistry concepts, how should the reactivity of PsCl for alcohol activation (or amino-group sulfonylation) be expected to compare to TsCl?
Obviously, like MsCl, PsCl has access to alpha-carbon protons (though at least somewhat less acidic due to the longer alkyl chain of EDGs), so sulfene intermediates would be expected to form in the case of a sufficiently strong base such as triethylamine or DIPEA. Then, generating less of a reactive sulfene intermediate at a given time (compared to MsCl, see https://doi.org/10.1021/jo981532p for reference) should favor PsCl's use in ensuring greater selectivity in sulfonylation (specifically, when one substrate site is more nucleophilic than another). From a structural perspective, I am inclined to think of PsCl as being TsCl minus the methyl group and the "bottom" (from a 2-D perspective) three C-atoms of TsCl's benzene ring (along with, of course, no C-C double bonds), so sterically-speaking PsCl's S-atom should be at-least-slightly more available for a nucleophilic attack (e.g., courtesy of a weaker base like pyridine). Though, from the electronics-perspective I'm not sure what impact TsCl's aromaticity would have on the S-atom's electrophilic character (charge delocalization perhaps leading to greater electrophilicity?). TsCl also naturally doesn't have an alpha-carbon with protons, which would seem to preclude its having an E1cB or E2-like reaction capacity.
Here is a paper (https://doi.org/10.1021/jo00821a030) in which one can see that the rate of secondary hydroxy group activation in anhydrous pyridine (serving as solvent, in addition to catalyzing hydroxy-group activation) clearly proceeded faster for PsCl than TsCl. Since pyridine would be catalyzing hydroxy-group activation through an SN2-like attack on the PsCl/TsCl S-atom, this would seem to indicate that steric factors play some role in PsCl being more reactive than TsCl.
