Noncatalytic Organic Synthesis Using Supercritical Water: The Peculiarity Near the Critical Point

Pinacol and Beckmann rearrangements can be carried out effectively by using supercritical water (scH(2)O) both as an acid catalyst as well as a medium. In the near-critical region not only are the rates significantly accelerated (see picture), but the nature of supercritical water can be adjusted to give weak acidity, which opens a new reaction pathway to a Diels-Alder adduct between dehydrated products.