Fig. 2.

Reaction scheme for the hydrogenation of cinnamaldehyde. Reaction pathways for CALD hydrogenation as observed for Pd/C catalysts at 80 °C, 90 mg ml⁻¹ of CALD in dioxane, 100 mg catalyst, and 20 ml min⁻¹ hydrogen flow rate at ambient pressure. Only two products were formed under the reaction conditions selected in the present study: HCALD through C=C bond hydrogenation, and PPL through a hydrogenation pathway that does not involve HCALD (i.e., tests performed with HCALD as the reactant showed no conversion, in agreement with Jiang et al. ³⁵). CALC and reaction byproducts were not detected, in agreement with the high (> 97%) carbon balance (Supplementary Tables 2 and 3)