ORGANIC DISULFIDES AND RELATED SUBSTANCES .26. PREPARATION AND OXIDATION OF CYCLIC DISULFIDES

1,2-Dithiolane, 1,2-dithiane, and 1,2-dithiepane were prepared and oxidized to the corresponding dioxides and tetroxides, two of the dioxides and all the tetroxides being obtained for the first time. Alternative routes were compared in the hope that the information will prove useful in the class of cyclic disulfides as a whole. 1,2-Dithiolane seemed best prepared by oxidation with hydrogen peroxide at 75° of 1,3-propanedithiol in acetic acid containing potassium iodide or through depolymerization of its polymer, 1,2-dithiane by cyclization of 1,4-butanedithiol with p-toluenesulfonyl chloride or of the lead dithiolate with sulfur, and 1,2-dithiepane by a reported oxidation with ferric chloride. Oxidation of 1,2-dithiane to the 1,1-dioxide and 1,1,2,2-tetroxide was best achieved using hydrogen peroxide in acetic acid, as were oxidation of 1,2-dithiolane and 1,2-dithiepane to their 1,1-dioxides. The tetroxides of 1,2-dithiolane and 1,2-dithiepane, not obtainable directly from the cyclic disulfides, were prepared by oxidizing the dioxides. Oxidation with ozone of the cyclic disulfides gave mixtures of the corresponding dioxides and (presumed) sulfonic anhydrides. Neither ethyl disulfide nor its disulfide dioxide could be oxidized to the corresponding tetroxide. © 1969, American Chemical Society. All rights reserved.