Oxyfunctionalization of natural terpenes catalyzed by La 1−x Sr x MnO 3 in water as solvent: an experimental and theoretical study

The catalytic behavior of La 0.4 Sr 0.6 MnO 3 ( PM3 ), La 0.8 Sr 0.2 MnO 3 ( PM2 ), and LaMnO 3 ( PM1 ) has been studied in the oxidation of natural terpenes (α-pinene, β-pinene, limonene, and valencene) in water. To find the best catalytic performance, several parameters were investigated such as the catalyst amount, the nature of the oxidant agent, the oxidant ratio, the temperature, the reaction time, and the nature of the solvent with the α-pinene as the model substrate. PM3 catalyst exhibited the best activity in the oxidation reaction using hydrogen peroxide as an oxidant agent giving a good yield towards verbenone with 50%. The recyclability of the catalyst performances showed remarkable stability after four cycles. Moreover, the photocatalytic mechanism of α-pinene using La 1−x Sr x MnO 3 catalyst was performed through the density functional theory method, and the possible attack site for the photocatalytic reaction between α-pinene and the hydroperoxyl radical (⋅OOH) was predicted using the condensed Fukui function and obtained findings are in good agreement with the experimental results.