Comparative hydroamination of aniline and substituted anilines with styrene on different zeolites, triflate based catalysts and their physical mixtures

• Hydroamination of aniline and substituted anilines with styrene.
• An enhanced activity and selectivity provided by physical mixtures.
• Reports on effect of ultrasounds irradiation on the preparation of physical mixtures.
• A control of the selectivity by the type of catalyst's acidity and the substrate.

Catalytic performances of different zeolites (Beta and mordenites), scandium triflate based catalysts, mesoporous UVM-7 encapsulated scandium triflate and physical mixtures prepared under ultrasound irradiation were evaluated in the hydroamination of aniline and substituted anilines with styrene. The performances of these catalysts were controlled by the type of acidity and strength. Thus, the conversion was mainly controlled by the strength of the acid sites and their accessibility, while the selectivity appeared to be controlled by the Lewis/Brønsted type of acidity. Lewis acid catalysts directed the reactions mainly to the formation of the Markovnikov adducts while Brønsted acid catalysts to anti-Markovnikov. Zeolites and scandium triflate led to results very close to those reported in the literature. Among different physical mixtures those of scandium triflate with the mesoporous scandium triflate embedded in a UVM-7 structure provided better conversions with a good selectivity in the Markovnikov adduct. These results were attributed to a better dispersion of scandium triflate during the preparation of physical mixtures.

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