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Fe 3 O 4 ‐Methylene diphenyl diisocyanate‐guanidine (Fe 3 O 4 –4,4′‐MDI‐Gn): A novel superparamagnetic powerful basic and recyclable nanocatalyst as an efficient heterogeneous catalyst for the Knoevenagel condensation and tandem Knoevenagel‐Michael‐cyclocondensation reactions
Author(s) -
Maleki Razieh,
Koukabi Nadiya,
Kolvari Eskandar
Publication year - 2018
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.3905
Subject(s) - knoevenagel condensation , thermogravimetric analysis , chemistry , catalysis , superparamagnetism , nuclear chemistry , decantation , scanning electron microscope , methylene , organic chemistry , magnetization , materials science , physics , quantum mechanics , magnetic field , composite material
In this paper, guanidine groups (Gn) supported on modified magnetic nanoparticles (Fe 3 O 4 –4,4′‐MDI) were synthesized for the first time. The catalyst synthesized was characterized by various techniques such as SEM (Scanning Electron Microscopy), TEM (Transmission electron microscopy), XRD ( X‐ray Diffraction), TGA (Thermogravimetric ananlysis), EDS ( Energy‐dispersive X‐ray spectroscopy) and VSM (vibrating sample magnetometer). The catalyst activity of modified MNPs–MDI‐Gn, as powerful basic nanocatalyst, was probed through the Knoevenagel and Tandem Knoevenagel–Michael‐cyclocondensation reactions. Conversion was high under optimal conditions, and reaction time was remarkably shortened. This nanocatalyst could simply be separated and recovered from the reaction mixture by simple magnetic decantation and reused many times without significant loss of its catalytic activity. Also, the nanocatalyst could be recycled for at least seven (Knoevenagel condensation) and six (Knoevenagel and Tandem Knoevenagel–Michael‐cyclocondensation) additional cycles after they were separated by magnetic decantation and, washed with ethanol, air‐dried, and immediately reused.