Diacetone-L-sorbose (DAS) is an intermediate product in the synthesis of ascorbic acid. DAS is obtained by acetonating L-sorbose in the presence of a catalyst. Possible catalysts are oleum, zinc chloride, copper sulfate, sulfonic acids, and ion exchange resins. In addition to DAS, the process of sorbose acetonation yields 1, 2-and 2, 3-monoacetonesorbose (1, 2- and 2, 3-MAS)[1]:
