Design and synthesis of the basic Cu-doped zeolite X catalyst with high activity in oxidative coupling reactions

• A highly crystalline Cu-doped zeolite X (Cu-X) was successfully synthesized.
• Cu-X shows high activity in the oxidative coupling of cinnamic acids with alcohols.
• Cu-X shows good performance in the oxidative coupling of alkenes with aldehydes.
• The Lewis basic sites in Cu-X can activate the CC bond in cinnamic acid.

The decarboxylative coupling of cinnamic acids with alcohols and the oxidative coupling of alkenes with aldehydes are typical organic reactions. Considering the characteristics and mechanisms of the reactions, the Cu-doped zeolite-X catalyst (Cu-X) with Lewis basic sites was synthesized and used for the two reactions. Compared with Cu, Cu2O, and CuBr2 catalysts (4–21%), the Cu-X catalyst (99%) shows extraordinary high activity in the decarboxylative coupling of cinnamic acids with alcohols. In addition, the Cu-X catalyst presents excellent performance in the oxidative coupling of alkenes with aldehydes. The strong interaction between Cu+ and the zeolite framework benefits the transformation of Cu2+ and Cu+ in the redox process, enhancing the reaction activity. More importantly, the Lewis basic sites on the Cu-X catalyst could favor the adsorption of the cinnamic acid, resulting in electron-rich density in the CC bond, and therefore greatly improving the reaction activity.

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