Hydrophobic <i>N,N-</i>Diarylammonium Pyrosulfates as Dehydrative Condensation Catalysts under Aqueous Conditions

Oil-soluble <i>N,N-</i>diarylammonium pyrosulfates as nonsurfactant-type catalysts for the dehydrative ester condensation under aqueous conditions are described. Preheat treatment of dibasic sulfuric acid with bulky <i>N,N-</i>diarylamines generates water-tolerant salts of pyrosulfuric acid as active catalyst species. The present catalysts in water can also widely be applied to unusual selective esterifications and dehydrative glycosylation.