On the reactions of alkanedithiols with picryl halides

The reaction of picryl chloride with ethane-1,2-dithiol and base leads to a spiro-σ-adduct via the initially formed 2-picrylthioethanethiol. Similar behaviour has been found with propane-1,3-diol and picryl iodide. In contrast, with propane-1,3-dithiol in place of ethane-1,2-dithiol the initially formed 3-picrylthiopropane-1-thiol collapses via intramolecular displacement of an ortho-nitro-group; no spiro-σ-adduct was detected. With butane-1,4-dithiol or pentane-1,5-dithiol and picryl chloride only polymers were isolated.