1-((4-((4-Hydroxyphenyl)sulfonyl)phenoxy)sulfonyl)pyridin-1-ium is an intermediate in synthesizing Bisphenol S Monosulfate (B519625), a metabolite of Bisphenol S (B447390), which is a commonly used as a reactant in epoxy reactions and is also used as a latent thermal catalyst for epoxy resin.