Zinc peroxide as a convenient and recyclable source of anhydrous hydrogen peroxide and its application in the peroxidation of carbonyls

Abstract

In this work, ZnO₂ was unexpectedly discovered as a friendly and renewable source of anhydrous hydrogen peroxide in the acid-catalyzed synthesis of cyclic organic peroxides from carbonyl compounds. In particular, five classes of cyclic organic peroxides, namely, γ-hydroperoxy-γ-peroxylactones, β-hydroperoxy-β-peroxylactones, bridged ozonides, bridged 1,2,4,5-tetraoxanes, tricyclic monoperoxides, and tricyclic diperoxides, were synthesized in good yields using in situ generated H₂O₂ from the reaction of ZnO₂ with H₂SO₄. This approach is convenient, safe, and does not require a concentrated aqueous or ethereal solution of H₂O₂. The starting ZnO₂ was synthesized from zinc acetate using a 1 wt% H₂O₂ solution. The reaction of zinc peroxide with sulfuric acid in an organic solvent results in the release of hydrogen peroxide and the formation of zinc sulfate, which acts as a desiccant by forming a monohydrate phase, ZnSO₄·H₂O. The possibility of recycling zinc peroxide from zinc sulfate monohydrate with a high yield was shown.