Ceric Ammonium Research Articles

Regioselective semi-synthesis of 6-isomers of 5,8-O-dimethyl ether of shikonin derivatives via an \u2018intramolecular ring-closing/ring-opening\u2019 strategy as potent anticancer agents

Synthesis of 6-isomer of 5,8-O-dimethyl ether of shikonin (13), a promising anticancer scaffold, always remains a huge challenge. Herein a key intermediate for 13, 2-(1-hydroxyl-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene (10), was obtained on the large-scale synthesis. A ring-closing/ring-opening strategy was applied to avoid the undesired reactivity posed by the side chain and racemization of the chiral centre. Incorporation of bulky substituent 4-((tertbutoxycarbonyl)amino)phenyl to hydroxyl group in the side chain redistributed electron density of naphthalene core (10), overwhelmingly favoring the generation of 13 when oxidized by cerium(IV) ammonium nitrate followed by hydrolysis. As a result, three 6-isomers (14a–14c) with very potent antitumor activity were easily synthesized. This study opened an novel avenue to selectively prepare 6-isomers of 5,8-dimethoxy1-1,4-naphthaquinones, bearing the synthetically challenging side chain such as 2-hydroxyl-5-methylpentenyl group.Graphical abstractA novel semi-synthesis of 6-isomer of 5,8-O-dimethyl ether of shikonin (13) was developed in a threestep rounte using a ring-closing/ring-opening strategy and a bulky substituent-mediated oxidative demethylation one

Thermal decomposition synthesis, characterization and electrochemical hydrogen storage characteristics of Co3O4–CeO2 porous nanocomposite

Particle-like Co3O4–CeO2 nanocomposite was synthesized via a facile thermal decomposition process in the presence of fructose as a green capping agent and ammonium cerium(IV) nitrate as Ce source. The effect of various parameters such as different cobalt sources, calcination temperature and time were investigated on the size and morphology of products. The transmission electron microscopy observations indicated that the synthesized products have a particle-like shape with an average diameter of 18–35 nm. For the first time, the electrochemical hydrogen storage performance of Co3O4–CeO2 porous nanocomposite was investigated via chronopotentiometry method in aqueous KOH solution in this paper. The electrochemical measurements showed that this product has a good hydrogen storage capacity at room temperature. Its maximum discharge capacity was 5200 mAh/g after 20 cycles. Therefore, Co3O4–CeO2 porous nanocomposite showed that it is a good candidate for electrochemical hydrogen storage.

Preparation of poly(acrylamide) grafted onto crosslinked poly (HEMA-MMA-EGDMA) beads for the removal of phenol

ABSTRACTPoly(acrylamide) (PAAM) was grafted onto crosslinked poly(hydroxy ethyl methacrylate) (HEMA)-based beads for the removal of phenol from aqueous solution. A beaded polymer with a PAAM surface shell was prepared in two steps: synthesis of crosslinked poly (HEMA (50% mol) - MMA (40% mol) - EGDMA (10% mol)) terpolymers spherical beads (200–420 µm) (resin 1) via the suspension polymerization method; and the grafting of PAAM was carried out by redox initiation from hydroxyl groups on resin1 by using cerium (IV) ammonium nitrate as the initiator.The resulting polymeric sorbent (resin 2) with about 82 wt.% grafted PAAM has been demonstrated to be efficient to remove phenol from water. Moreover, phenol sorption capacities of resin 1 and resin 2 were compared and sorption experiments were performed depending on the initial phenol concentration and pH. Kinetic measurements and models were studied for resin 1 and resin 2.

Synthesis of ferrocene boronic acid-based block copolymers via RAFT polymerization and their micellization, redox responsive and glucose sensing properties

Current study is focused on the synthesis of three novel diblock copolymers poly(2-methacryloyloxy)ethyl ferrocene carboxylate-b-polymethyl vinyl amido phenyl boronic acid, poly(2-methacryloyloxy)ethyl ferrocene carboxylate-b-poly vinylamido phenyl boronic acid and poly(2-methacryloyloxy)ethyl ferrocene carboxylate-b-polystyrene boronic acid using S-methoxycarbonylphenylmethyl dithiobenzoate as reversible addition–fragmentation chain transfer polymerization agent. The synthesized block copolymers were characterized by gel permeation chromatography, fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, dynamic light scattering, scanning electron microscopy and transmission electron microscopy. Detailed micellization behaviour of poly(2-methacryloyloxy)ethyl ferrocene carboxylate-b-polymethyl vinyl amido phenyl boronic acid (in binary organic solvents mixture and aqueous solution) was studied. Comparative studies of micellization showed that the larger aggregates were obtained in binary organic solvents system than during dialysis in aqueous medium. The redox responsive behaviour of poly(2-methacryloyloxy)ethyl ferrocene carboxylate-b-polymethyl vinyl amido phenyl boronic acid was investigated by water soluble oxidizing (Ammonium cerium nitrate) and reducing (Sodium hydrogen sulphite) agents. Glucose binding/sensing properties of poly(2-methacryloyloxy)ethyl ferrocene carboxylate-b-polymethyl vinyl amido phenyl boronic acid were also explored by micellization. It was found that the increase in polarity and swelling of poly(2-methacryloyloxy)ethyl ferrocene carboxylate-b-polymethyl vinyl amidophenyl boronic acid micelles was due to the redox behaviour of ferrocene, while binding of glucose with boronic acids hydroxyls appears as unimers or small aggregates.

Use of boiled hexamethylenetetramine and urea to increase the porosity of cerium dioxide microspheres formed in the internal gelation process

Cerium dioxide (CeO2) is a commonly used simulant for plutonium dioxide and for plutonium (Pu) in uranium (U) and Pu oxide [(U, Pu)O2] mixtures used in nuclear fuel development. This effort developed CeO2 microspheres with a various porosities and diameters. The internal gelation technique has only been used to produce CeO2 microspheres with limited initial porosity. Previous studies have shown that the crystallite size and porosity of mixed U and thorium oxide microspheres and the (U, Pu)O2 microspheres from the internal gelation process increased when an equal molar solution of hexamethylenetetramine (HMTA) and urea is gently boiled for 1 h prior to its use in the gelation process. In this study with cerium, the combination of ammonium cerium nitrate and 1-h boiled HMTA-urea failed to produce a stable feed broth. However, when the 1-h heated HMTA-urea was combined with unheated HMTA-urea in 1–3 vol ratio or the boiling time of the HMTA-urea was reduced to 15–20 min, a stable solution of HMTA, urea, and Ce was formed at 273 K. This new Ce solution produced very porous CeO2 microspheres, which are suitable simulants for uranium microspheres.

Cerium(IV) ammonium nitrate for the tandem nitration and oxidative rearrangement of 2-acetyl-1-naphthol benzoylhydrazones into 1,2-diacylnaphthalenes; synthesis of benzo[f]phthalazines

Cerium(IV) ammonium nitrate for the tandem nitration and oxidative rearrangement of 2-acetyl-1-naphthol benzoylhydrazones into 1,2-diacylnaphthalenes; synthesis of benzo[f]phthalazines

Crystal structure of methyl (4R)-4-(4-meth-oxy-benzo-yl)-4-{[(1R)-1-phenyl-eth-yl]carbamo-yl}butano-ate.

The title compound, C22H25NO5, was prepared by CAN [cerium(IV) ammonium nitrate] oxidation of the corresponding β-lactam. The dihedral angle between the benzene rings is 13.3 (4)° and the C-N-C(=O)-C torsion angle is 176.1 (6)°. In the crystal, amide-C(4) N-H⋯O and reinforcing C-H⋯O hydrogen bonds link the mol-ecules into infinite [010] chains. Further C-H⋯O hydrogen bonds cross-link the chains in the c-axis direction.

Mesoporous cerium-doped titania for the photocatalytic removal of persistent dyes

Mesoporous titanium dioxide was prepared by Evaporation Induced Self Assembly (EISA) method from titanium isopropoxide as precursor, and cetyl-trimethyl-ammonium bromide as surfactant. This sample was doped with cerium oxide by incipient wetness impregnation (IWI), using cerium ammonium sulfate. Two other samples of mesoporous TiO2 doped with cerium oxide were prepared by EISA, using cerium ammonium sulfate and cerium nitrate as precursors. The samples were calcined at 773, 873 and 973K to remove the templating surfactant. The powder XRD characterization indicated the formation of anatase structure for all the calcination temperatures. The investigation of the porous structure by pure nitrogen adsorption at 77K (BET method) showed that the samples had specific surface areas between 25 and 190m2g−1 and free pore volumes of 0.15–0.35cm3g−1, depending strongly on the nature of the dopant and the preparation procedure. The band gap values of the materials deduced by UV-DR spectroscopy were situated between 2.35–2.93eV. The photocatalytic tests indicated yields of up to 72% for Rhodamin 6G decolorization under UV irradiation. The photocatalytic performances of the different samples were correlated to the results of XPS spectra, the best behavior being due to the synergetic effect of Ce (III), Ce (IV) and Oα species, involved in HO radicals obtaining.

Photocatalysis of S-metolachlor in aqueous suspension of magnetic cerium-doped mTiO2 core-shell under simulated solar light.

Magnetic cerium-doped mesoporous titanium dioxide was synthesized by combining sol-gel method and calcination using tetrabutanate and ammonium cerium nitrate as precursors and Pluronic P123 as a template coating on iron oxide covered with carbon in ethanol. The magnetic Ce-doped catalyst showed only anatase structure with a slight increase in lattice parameters compared to the undoped catalyst. The Ce LIII-edge X-ray absorption near-edge spectroscopy (XANES) spectra showed Ce3+, and the cerium substitution doping into titanium dioxide was proposed. Degradation of S-metolachlor in aqueous magnetic photocatalyst suspension followed (pseudo) first-order kinetics in the presence of 0.5gL-1 of γ-Fe2O3@C@0.16mol% Ce-mTiO2 with a half-life of 55.18±1.63min. Fifteen degradation products were identified, and their transformation routes of the photocatalytic degradation were then proposed. Complementary toxicity assessment of the treated S-metolachlor solution was undertaken with Environment Canada's algal microplate assay measuring growth inhibition (72-h IC50) in the freshwater chlorophyte Pseudokirchneriella subcapitata. This test method revealed a significant decrease in toxicity (1.7-fold reduction after 180min of irradiation treatment), thereby confirming that the by-products formed following photocatalysis would be less harmful from an environmental point of view. Photocatalytic degradation of S-metolachlor thus appears to hold promise as a cost-effective treatment technology to diminish the presence of this herbicide in aquatic systems.

3,3-(Butane-1,4-diyl)bis(1,2-dimethyl-1H-imidazole-3-ium)bromide–cerium(IV) ammonium nitrate: A novel reagent for mild synthesis of 12-aryldibenzo[i,b]pyrano[4,3-b]chromenone of benzyl alcohols

A novel and efficient procedure for the synthesis of pyrano[4,3-b]chromene derivatives via three-component condensation reaction of benzyl alcohol, β-naphthol, and 4-hydroxycoumarin using a catalytical amount of cerium(IV) ammonium nitrate (CAN) and a reusable ionic liquid as a catalyst at room temperature is presented. The method provides several advantages such as simple work-up, environmental friendliness and shorter reaction time along with high yields. All synthesized compounds were elucidated by comparison with authentic samples, IR, 1H, and 13C NMR spectroscopy, and elemental analysis.

Effect of reactive functionalization on properties and degradability of poly(lactic acid)/poly(vinyl acetate) nanocomposites with cellulose nanocrystals

Nanocomposites of poly(lactic acid) (PLA) containing cellulose nanocrystals (CNCs) were prepared by dispersion of CNCs in aqueous poly(vinyl acetate) (PVAc) emulsion followed by melt extrusion with PLA. Functionalization of PVAc by radical grafting of glycidyl methacrylate (PVAc-GMA) was carried out during PVAc polymerization by using ammonium cerium (IV) nitrate as the initiator. The morphology, phase interactions, thermal and mechanical properties and degradability in composting of blends (PLA/PVAc, PLA/PVAc-GMA) and nanocomposites (PLA/PVAc/CNC, PLA/PVAc-GMA/CNC) containing 3wt% CNC were examined by FESEM, AFM, FT-IR, DSC and tensile tests. The study of degradability demonstrated that the disintegration rate of PLA/PVAc-GMA/CNC in soil was higher than that of PLA/PVAc/CNC, likely because the epoxy groups of GMA accelerated the biodegradation rate through the formation of radicals.

ChemInform Abstract: Synthesis of Spiro‐Lactams and Polysubstituted Pyrroles via Ceric Ammonium Nitrate‐Mediated Oxidative Cyclization of N‐Furan‐2‐ylmethyl‐β‐enaminones.

AbstractPolysubstituted pyrroles and diastereoisomeric mixtures of spirolactams are obtained by reacting furfurylamines with ynones followed by oxidation with different amounts of CAN.

Zr(IV) and Ce(IV)-based metal-organic frameworks incorporating 4-carboxycinnamic acid as ligand: Synthesis and properties

Two new microporous metal-organic framework materials constructed from Zr(IV) (1) or Ce(IV) (2) ions and 4-carboxycinnamate (CCA) ligand are presented. 1 was prepared by heating a mixture of ZrCl4, H2CCA ligand and acetic acid with a molar ratio of 1:1:10 in N,N′-dimethylformamide (DMF) at 150 °C for 24 h. 2 was synthesized by solvothermal reaction of a mixture of ammonium cerium(IV) nitrate and H2CCA ligand in a DMF/H2O mixture at 100 °C for 20 min. The as-synthesized and the thermally activated forms (1′ and 2′) of the compounds were characterized by X-ray powder diffraction (XRPD), Fourier transform infrared (FT-IR), thermogravimetric (TG) and elemental analysis. 1 and 2 show high thermal stability up to 390 and 300 °C in air atmosphere, respectively. According to XRPD measurements, both compounds show moderate stability in water, but they lose their crystallinity in 1 M HCl. N2 sorption experiments reveal that 1′ and 2′ possess BET surface areas of 870 and 1210 m2 g−1, respectively. The CO2 uptake values of 1′ and 2′ at 0 °C and 1 bar are 2.0 and 1.6 mmol g−1, respectively.

Water-oxidizing activity of ZSM-5 type manganosilicate: The importance of the Mn[sbnd]O[sbnd]Mn bonds

Water-splitting into O2 and H2 is a promising way to prepare eco-friendly fuels in the future. However, the water-oxidation is the bottleneck for this important reaction. Thus, finding more details of water-oxidation mechanism leads to design more efficient water-splitting catalysts for the hydrogen evolution reaction. Herein, an aluminum-free manganese incorporated ZSM-5 type zeolite is synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy (DRS), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Atomic absorption spectroscopy (AAS), Transmission electron microscopy (TEM) and N2 physical adsorption analysis. The water-oxidizing activity of the synthesized sample is studied in the presence of ammonium cerium(IV) nitrate as an oxidant. Water-oxidation experiments confirm that direct cooperation between Mn ions is one of the most important factors for the water-oxidation by Mn oxides.

Synthesis of Nororipavine and Noroxymorphone via N- and O-Demethylation of Iron Tricarbonyl Complex of Thebaine

Thebaine was converted into its iron tricarbonyl complex, which underwent successive N- and O-demethylation with BrCN and BBr 3 , respectively. Decomplexation of the iron tricarbonyl moiety was accomplished with ammonium cerium(IV) nitrate (CAN) and base-catalyzed hydrolysis furnished nororipavine. When excess CAN was used the methoxydiene unit was converted into its C-14 nitrate that on hydrogenation and further hydrolysis furnished noroxymorphone. Full experimental and spectral data are provided for all key compounds.

Convergent Synthesis of Menaquinone-7 (MK-7)

A practical synthesis of menaquinone-7 (MK-7, vitamin K2) in the all-trans form was designed. Stereoselective synthesis of MK-7 was achieved through a “1 + 6” convergent strategy by condensation of two building blocks, menadione monoprenyl derivative (fragment “1”) with hexaprenyl bromide (fragment “6”, 82%). Pd-catalyzed desulfonation with LiEt3BH (78%) was followed by oxidation of the hydroquinone moiety using ammonium cerium(IV) nitrate (72%). The major challenge in our methodology was the preparation of all-trans hexaprenyl bromide by coupling of two triprenyl units derived from trans,trans-farnesol. Manufacturing on a pilot scale was accomplished through our approach. The scalable method was designed especially for a large, kilogram-scale production from easily available intermediates. Furthermore, the proposed methodology avoids many chromatographic purifications and allows for a relatively cost-effective manufacturing. Moreover, our synthesis yielded high-purity (99.9%) final product MK-7, which ca...

Synthesis of Nororipavine and Noroxymorphone via N- and O-Demethylation of Iron Tricarbonyl Complex of Thebaine

Thebaine was converted into its iron tricarbonyl complex, which underwent successive N- and O-demethylation with BrCN and BBr₃, respectively. Decomplexation of the iron tricarbonyl moiety was accomplished with ammonium cerium(IV) nitrate (CAN) and base-catalyzed hydrolysis furnished nororipavine. When excess CAN was used the methoxydiene unit was converted into its C-14 nitrate that on hydrogenation and further hydrolysis furnished noroxymorphone. Full experimental and spectral data are provided for all key compounds.

Synthesis and evaluation of a novel cationic konjac glucomannan-based flocculant

A novel cationic flocculant of konjac glucomannan-graft-poly-(2-methacryloyloxyethyl)trimethyl ammonium chloride (KGM-g-PDMC), was successfully synthesized by using acidic ammonium cerium (IV) nitrate (CAN) as initiator in homogeneous aqueous solution. The graft copolymer was characterized using Fourier-transform infrared (FT-IR) spectroscopy, 1H nuclear magnetic resonance (1H NMR), thermogravimetric analysis (TGA) and elemental analysis. The influences of degree of substitution (DS) of KGM, concentration of NaCl and pH value on turbidity removal rate of the cationic flocculant were investigated. The results demonstrated that the flocculant exhibited excellent flocculating ability in the presence of salt and a wide range of pH (1<pH<9). With DS of 0.2, the turbidity removal rate of flocculant to 0.1% kaolin suspension could reach more than 90% at pH 7.0. The flocculation mechanisms were investigated by screening effect and means of zeta potential. Holding the positive charge, the KGM-g-PDMC could efficiently remove the negatively charged contaminants such as kaolin suspension.

Nano-sized Mn oxide/agglomerated silsesquioxane composite as a good catalyst for water oxidation.

Water splitting to hydrogen and oxygen is an important reaction to store sustainable energies, and water oxidation is identified as the bottleneck for water splitting because it requires the high activation energy to perform. Herein a nano-sized Mn oxide/agglomerated silsesquioxane composite was used to synthesize an efficient catalyst for water oxidation. The composite was synthesized by a straightforward and simple procedure and characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, dynamic light scattering, X-ray diffraction spectrometry, and electrochemical methods. Silsesquioxane causes good dispersion of Mn in the composite. The water-oxidizing activity of this composite was studied in the presence of cerium(IV) ammonium nitrate. The composite at the best calcination temperature (300°C) shows a turnover frequency 0.3 (mmol O2/mol Mn.s). Regarding the low-cost, environmentally friendly precursors, simple synthesis, and efficiency for water oxidation, the composite is a promising catalyst that can be used in artificial photosynthetic systems for water splitting. We used Agglomerated silsesquioxane as a support for nano-sized Mn oxide to synthesize a good water-oxidizing catalyst.

Preparation method of Ce1−x Zr x O2/tourmaline nanocomposite with high far-infrared emissivity and its mechanism

Far-infrared functional nanocomposites were prepared by the coprecipitation method using natural tourmaline (XY3Z6Si6O18(BO3)3V3W, where X is Na+, Ca2+, K+, or vacancy; Y is Mg2+, Fe2+, Mn2+, Al3+, Fe3+, Mn3+, Cr3+, Li+, or Ti4+; Z is Al3+, Mg2+, Cr3+, or V3+; V is O2−, OH−; and W is O2−, OH−, or F−) powders, ammonium cerium(IV) nitrate and zirconium(IV) nitrate pentahydrate as raw materials. The reference sample tourmaline modified with ammonium cerium(IV) nitrate alone was also prepared by a similar precipitation route. The results of Fourier transform infrared spectroscopy show that Ce–Zr can further enhance the far-infrared emission properties of tourmaline than Ce alone. Through characterization by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), the mechanism by which Ce(–Zr) acts on the far-infrared emission property of tourmaline was systematically studied. The XPS spectra show that the Fe3+ ratio inside tourmaline powders after heat treatment can be raised by doping Ce and further raised after adding Zr. Moreover, it is showed that Ce3+ is dominant inside the samples, but its dominance is replaced by Ce4+ outside. In addition, XRD results indicate the formation of CeO2 and Ce1−x Zr x O2 crystallites during the heat treatment, and further, TEM observations show they exist as nanoparticles on the surface of tourmaline powders. Based on these results, we attribute the improved far-infrared emission properties of Ce–Zr-doped tourmaline to the enhanced unit cell shrinkage of the tourmaline arisen from much more oxidation of Fe2+ (0.074 nm in radius) to Fe3+ (0.064 nm in radius) inside the tourmaline caused by Zr enhancing the redox shift between Ce4+ and Ce3+ via improving the oxygen mobility in the Ce–Zr crystal.