One–pot A3–coupling solvent–free synthesis of propargylamines by Pd–impregnated Al–based LDHs synthesized from aluminum salt slag

• Pd–impregnated LDHs were ecofriendly synthesized from aluminum salt cake. • Propargylamines were synthesized solvent – free using Pd–LDHs as catalyst. • The Pd–nial catalyst showed the best results in A 3 –coupling reaction. • Optimum reaction conditions were: catalyst dosage 30 mg, 5 h and 80 °C. • Good catalytic behavior of Pd–nial catalyst. Several Al 3+ –based LDHs with different divalent cations have been synthesized by coprecipitation from aluminum salt slag and have been impregnated with Pd. After their characterization by PXRD, FT–IR, thermal analysis, N 2 adsorption–desorption isotherms at –196 °C and electron microscopy (SEM and TEM), they were used as heterogeneous catalysts in the A 3 –coupling reaction (benzaldehyde + morpholine + phenylacetylene) to produce propargylamines. The catalyst that showed the best results was NiAl–Pd and the optimal reaction conditions were: catalyst dose 30 mg, temperature 80 °C and reaction time 6 h. In addition, this catalyst showed a good cyclic behavior, retaining a catalytic activity higher than 80 % after 4 cycles.