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Why do the tosylation and mesylation of an alcohol proceed via different mechanisms?
More specifically,
In tosylation, the lone pair of the alcohol attacks the sulfur in TsCl, but why does it not do so with MsCl? Surely, TsCl should be more sterically hindered due to the benzene ring.
Why is the sulfene intermediate even formed in mesylation? Can that position be deprotonated by $\ce{Et3N}$? It's clear that this mechanism cannot happen with TsCl which has no alpha protons, but I fail to see why it should happen with MsCl.
Tosylation with pyridine:
Mesylation with triethylamine:
2026-10-20
