Premium
Cu(II) immobilized on guanidinated epibromohydrin‐functionalized γ‐Fe 2 O 3 @TiO 2 (γ‐Fe 2 O 3 @TiO 2 ‐EG‐Cu(II)): A highly efficient magnetically separable heterogeneous nanocatalyst for one‐pot synthesis of highly substituted imidazoles
Author(s) -
Nejatianfar Mahdi,
Akhlaghinia Batool,
Jahanshahi Roya
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.4095
Subject(s) - chemistry , benzil , catalysis , ammonium acetate , magnetization , nuclear chemistry , condensation reaction , crystallography , inorganic chemistry , analytical chemistry (journal) , organic chemistry , high performance liquid chromatography , physics , quantum mechanics , magnetic field
A simple, efficient and eco‐friendly procedure has been developed using Cu(II) immobilized on guanidinated epibromohydrin‐functionalized γ‐Fe 2 O 3 @TiO 2 (γ‐Fe 2 O 3 @TiO 2 ‐EG‐Cu(II)) for the synthesis of 2,4,5‐trisubstituted and 1,2,4,5‐tetrasubstituted imidazoles, via the condensation reactions of various aldehydes with benzil and ammonium acetate or ammonium acetate and amines, under solvent‐free conditions. High‐resolution transmission electron microscopy analysis of this catalyst clearly affirmed the formation of a γ‐Fe 2 O 3 core and a TiO 2 shell, with mean sizes of about 10–20 and 5–10 nm, respectively. These data were in very good agreement with X‐ray crystallographic measurements (13 and 7 nm). Moreover, magnetization measurements revealed that both γ‐Fe 2 O 3 @TiO 2 and γ‐Fe 2 O 3 @TiO 2 ‐EG‐Cu(II) had superparamagnetic behaviour with saturation magnetization of 23.79 and 22.12 emu g −1 , respectively. γ‐Fe 2 O 3 @TiO 2 ‐EG‐Cu(II) was found to be a green and highly efficient nanocatalyst, which could be easily handled, recovered and reused several times without significant loss of its activity. The scope of the presented methodology is quite broad; a variety of aldehydes as well as amines have been shown to be viable substrates. A mechanism for the cyclocondensation reaction has also been proposed.