MgRuAl-layered Double Hydroxides (LDH): An Efficient Multifunctional Catalyst for Aldol Condensation and Transfer Hydrogenation Reactions

Abstract

Background: Layered double hydroxides (LDH) are drawing much attention as solid catalysts in recent years and have applications in various organic transformations as they possess a variety of basic sites which could be obtained by exchange of metal ions or by intercalation of suitable anions into their interlayer space. Ru based complexes have widespread catalytic applications in many organic reactions. Herein, novel ruthenium containing ternary LDH has been synthesized and used as a multifunctional catalyst for Aldol condensation and transfer hydrogenation reactions. Methods: Ternary LDH multifunctional catalyst containing Mg, Ru and Al was prepared by coprecipitation and hydrothermal treatment. The catalyst was characterized by elemental analysis, Powder XRD, FT-IR, BET, TGA, DRS, SEM, EDX, XPS and TEM. The products of the reactions were characterized by 1H NMR and GC-MS. Results: The analysis of catalyst revealed incorporation of Ru in the brucite layers of the LDH and showed the mosaic single crystal with BET surface area of 84.25 m2 g-1. This catalyst yielded 85–98% products for Aldol condensation reactions within 4 h reaction time, and 82–98% products for transfer hydrogenation reactions within 16 h reaction time. Conclusion: The resultant MgRuAl-LDH with acid and base sites was found to be highly active and selective for one-step synthesis of nitrile compounds. The catalyst works more efficiently for Aldol condensation reactions in shorter reaction times compared to transfer hydrogenation reactions.