Hydrogenation of 2-methylindole using supported metal catalysts

•Selective hydrogenation of 2-methylindole to 2-methylindoline•Hydrogenation using zeolites•Comparison of acidic zeolites with homogeneous acids•TOF for Ir/beta higher than for Pt/C with added p-toluenesulfonic acid

The hydrogenation of 2-methylindole to 2-methylindoline in toluene was studied at 60 °C and 40 bar hydrogen pressure in a batch mode using a range of carbon, alumina, and zeolite supported metal catalysts were performed in toluene. The results were compared with a more conventional catalytic system containing besides 5% Pt/C also 1.2 eq. of p-toluenesulfonic acid in ethanol:water (50:50 v/v). The highest turnover frequency (TOF) was obtained a zeolite supported iridium catalyst.