Synthesis of pure aromatic, aliphatic, and araliphatic diselenides

Organodiselenides are potential building blocks for a new class of self-assembled monolayers e.g. on coinage metals. For this, the diselenides have to be extremely pure and in particular must not contain any traces of higher organoselenides. Several strategies for the preparation of organodiselenides were compared in their efficiency in particular regarding the purity of the products. It could be shown that most literature-established procedures generate significant amounts of triselenides which are hard to detect with conventional analytic methods. While in case of the aromatic diselenides the direct synthesis via the corresponding Grignard reagent resulted in pure diselenides, the preparation of the aliphatic and araliphatic derivatives required a more indirect route through the corresponding selenocyanates.