This work describes the synthesis and characterization of a heterogeneous catalyst consisting of piperazine-functionalized reduced graphene oxide decorated with Fe3O4 nanoparticles ( Fe3O4@rGO-NH), and the study of its catalytic activity as a magnetic heterogeneous catalyst for the Pechmann synthesis of coumarins. Catalyst Fe3O4@ rGO-NH was fully characterized by various techniques, including IR, XRD, TEM, VSM, TGA, and elemental analysis. Then, the catalyst was used as an efficient and easy-separable heterogeneous catalyst for the solvent-free synthesis of some coumarins by Pechmann reaction. The reaction was optimized in terms of reaction time and temperature, catalyst dosage, and the presence/absence of the solvent. Finally, the reusability of the catalyst was studied.

    Abstract
    1 Introduction
    2 Results and discussion
        2.1 Synthesis and characterization of catalyst Fe3O4@rGO-NH
        2.2 FT-IR
        2.3 TGA​
        2.4 XRD
        2.5 TEM
        2.6 VSM
    3 Experimental
        3.1 General
        3.2 Synthesis of catalyst Fe3O4@rGO-NH
    4 Experimental procedure for the Pechmann reaction (synthesis of compounds 2a-j)
        4.1 7-Hydroxy-4-methyl-[2H]-chromen-2-one (2a)
        4.2 7,8-Dihydroxy-4-methyl-[2H]-chromen-2-one (2b)
        4.3 5,7-Dihydroxy-4-methyl-[2H]-chromen-2-one (2c)
        4.4 7-Methoxy-4-methyl-[2H]-chromen-2-one (2d)
    5 Conclusion
    References

• Esmail Rezaei‑Seresht(Department of Chemistry, School of Sciences, Hakim Sabzevari University)
• Fatemeh Tafazzoli Gazkoh(Department of Chemistry, School of Sciences, Hakim Sabzevari University)
• Behrooz Maleki(Faculty of Chemistry, University of Mazandaran)