Silver Cyanide Powder‐Catalyzed Selective Epoxidation of Cyclohexene and Styrene with its Surface Activation by H 2 O 2(aq) and Assisted by CH 3 CN as a Non‐Innocent Solvent

We undertake silver cyanide (AgCN) powder for its catalytic epoxidation of cyclohexene or styrene in CH 3 CN with variable substrate‐to‐solvent volume ratios using H 2 O 2(aq) at 60 °C. The reaction mixtures can facilely separate into organic and aqueous layers. Cyclohexene oxide can be produced in the organic layer with 100 % selectivity from the substrate cyclohexene, while styrene oxide was identified with 80 % selectivity against benzaldehyde in styrene oxidation. After reactions, we can recycle the AgCN particles with comparable bulk property clarified via XRD, XPS, XAS, FT‐IR, and 13 C‐SS NMR spectroscopy. Using H 2 18 O 2 as the oxidant, both epoxide products and acetamide are highly enriched with 18 O‐atom, indicating that the π bond‐activation is essential for forming the cyclohexene/styrene oxides in the organic and acetamide in the aqueous layers. The oxidation of cyclohexene/styrene catalyzed by AgCN powder through surface activation by H 2 O 2(aq) and assisted by the non‐innocent CH 3 CN‐originated acetamide can achieve highly selective π‐bond activation with high reactivity.