China
Africa
Explore chapters and articles related to this topic
N-Heterocycles
Published in Navjeet Kaur, Metals and Non-Metals, 2020
Various cyclic guanidines are important medicinal targets and exhibit potent biological activity. Cyclic guanidines can be prepared using many of the techniques used for the synthesis of imidazolidin-2-ones. For instance, as depicted in Scheme 28, Zhao et al. [55] reported that acyclic guanidine undergoes rhodium-catalyzed carbon-hydrogen amination for synthesizing a cyclic guanidine. In another study, they investigated intra- and intermolecular diaminations to produce cyclic guanidines.
Nano magnetite supported phthalocyanine complexes of Cu(II) and Fe(II) as new heterogeneous effective catalysts for synthesis of β-amido ketones
Published in Journal of Coordination Chemistry, 2018
Hossein Naeimi, Soraya Rahmatinejad
Phthalocyanine gives stable metal complexes with Fe and Cu. Phthalocyanine complexes can be prepared from free metals and their salts through chemical and electrochemical methods. Phthalocyanines hold the metal atom in the center of the ring by an electrovalent or a covalent bond [25]. Metal(II) phthalocyanine (M: Cu, Fe) was prepared from the reaction of phthalic anhydride, urea and copper(II) chloride dihydrate or iron(II) chloride tetrahydrate under microwave irradiation. The synthetic strategy for preparation of functionalized silica-coated MNPs is shown in Scheme 1. At first, magnetite nanoparticles were prepared by co-precipitation via iron(II) and iron(III) ions in a basic solution. Then, using tetraethylorthosilicate as the silica source, Fe3O4 core was coated with a layer of silica. This layer avoids any possible iron oxide aggregation or oxidation and provides reactive sites for further functionalization. The obtained Fe3O4@SiO2 nanoparticles were then functionalized with 3-chloropropyltrimethoxysilane (CPTMS). For preparing guanidine-modified Fe3O4@SiO2, Fe3O4@SiO2-CPTMS was treated with guanidine in water under ultrasound irradiation for 1 h (Fe3O4@SiO2-GA). Guanidine and its derivatives have been used in different organic reactions as a strong base catalyst [41]. Additionally, guanidines have found a lot of applications in coordination and organometallic chemistry as ligands and a large number of complexes containing guanidine ligand have been reported [42]. Ultimately, Fe3O4@SiO2-GA was treated with metal (Cu, Fe) Pc complexes in ethanol to yield the corresponding heterogeneous catalyst (Fe3O4@SiO2-GA-MPc).
Exploring the influence of urea on the proton-transfer reaction in aqueous amine solutions with Raman and ultrasonic relaxation spectroscopy
Published in Molecular Physics, 2023
M. Risva, S. Tsigoias, S. Boghosian, S. Kaziannis, A. G. Kalampounias
Guanidine is a strong base commonly used in the production of plastics and explosives, while in the human body it is detected in urine after protein metabolism [16]. In addition, guanidine under atmospheric conditions is a colourless liquid, soluble in polar solvents [17–19]. Guanidine corresponds to the nitrogen analog of carbonic acid where the (C=O) and (–OH) functional groups have been replaced by (C=NH) and (–NH2), respectively [17].