o-Benzenedisulfonimide as Reusable Brønsted Acid Catalyst for Acid-Catalyzed Organic Reactions

Acid-catalyzed organic reactions, such as etherification, esterification, acetal synthesis, cleavage, and interconversion, and pinacol rearrangement were carried out in the presence of catalytic amounts of o-benzenedisulfonimide as Brønsted acid catalyst; the conditions were mild and selective. The catalyst was easily recovered and purified, ready to be used in further reactions, with economic and ecological advantages.