Thermal reactions of organyl chalcogenides with α,β-unsaturated aldehydes

Thermal gas-phase reactions of acrolein, cinnamaldehyde, and benzaldehyde with diorganyl chalcogenides and diorganyl dichalcogenides were studied. Acrolein does not react with chalcogenides at 300–600°C but completely decomposes under reaction conditions. At 600–650°C, cinnamaldehyde reacts only with diorganyl selenides and diselenides to give benzoselenophene. Its highest yield (53%) is achieved in the reaction with dimethyl diselenide at 630°C and at an equimolar ratio of the reactant. The gas-phase reactions of benzaldehyde at 400–500°C afford chalcogen-containing derivatives of several types, among which thioanisole and its selenium or tellurium analogs predominate. The mechanisms of the above reactions were discussed in terms of homolytic substitution of the formyl group at unsaturated carbon atoms by chalcogenyl radicals.