Ecofriendly Synthesis of Ceria Foam via Carboxymethylcellulose Gelation: Application for the Epoxidation of Chalcone

Abstract

A simple and innovative process is described for the eco-friendly preparation of ceria foams via the carboxymethylcellulose gelation by Ce 4+ cations; heat treatment of the ensuing xerogels produces ceria foams. The influence of the concentration of cerium and of the calcination temperature of the xerogels is studied. Several characterization methods have been used and the obtained results demonstrate that this technique allows the controlled growth of ceria foams. The foamy structure apparently is responsible for UV absorption and the ceria foam is basic enough to promote the epoxidation of chalcone; comparison of the catalytic activity of the ceria foam versus ceria prepared via co-precipitation method shows that the ceria foam is most active as it promotes epoxidation of electron-deficient alkenes with dilute aqueous hydrogen peroxide. spectrometer equipped with a monochromatic Al Kα X-ray source (hν = 1486.6 eV), operating at 150 W, using a multi-channel plate and delay line detector under 1.0x10-9 Torr vacuum. The survey and highresolution spectra were collected at fixed analyzer pass energies of 160 and 20 eV, respectively. The instrument work function was calibrated to give an Au4f7/2 metallic gold binding energy of 83.95 eV.The spectrometer dispersion was adjusted to give a binding energy of 932.63 eV for metallic Cu 2p3/2. Samples were mounted in a floating mode in order to avoid differential charging; charge neutralization was required for all samples. The electronic binding energy of C 1s (284.80 eV) was used as the internal standard. These data were analyzed with commercially available software, CasaXPS. The individual peaks were fitted with a Gaussian (70%)-Lorentzian (30%) (GL30) function after Shirley type background subtraction. For the UV characterization, a spectrophotometer LAMBDA 1050 UV/Vis/NIR of the company PerkinElmer was used, with a wavelength range spanning from 100 nm to 3300 nm. SYNTHESIS OF CERIA FOAMS.The synthesis of ceria foams was accomplished using the carboxymethylcellulose (CMC) gel. 5 g of CMC were dissolved in 100 mL of deionized water (18 MΩ) at room temperature, forming a viscous solution. A separate solution was prepared by dissolving 5.5g of (NH 4 ) 2 Ce(NO 3 ) 2 in 100 mL of deionized water. Then, the CMC gel (5%: w/w) was added dropwise, at room temperature, to the cerium (IV) precursor solution via a syringe with a 0.8 mm diameter needle and constantly stirred for 1 hour. The hydrogels obtained were washed with distilled water then dried at room temperature for 24 hours or by supercritical CO 2 in order to prepare xerogels and aerogels, respectively. These beads (xerogels or aerogels) were then calcined at different temperature (350°C, 500 °C, 700 °C, 900 °C and 1100 °C). CATALYTIC APPLICATION-EPOXIDATION OF CHALCONE WITH H 2 O 2 .Chalcone (0.581 mmol), methanol (1 mL), and catalyst (0.5 %mol) were added to a 10 mL flask. The reaction was started with the addition of aqueous hydrogen peroxide (30 wt%, 0.35 mL) at room temperature within the appropriate time under stir...

One Pot and Two Pot Synthetic Strategies and Biological Applications of Epoxy-Chalcones

“…Hydrogen peroxide (H 2 O 2 ) with sodium hydroxide in THF [27], ceric foam (CeO 2 ) [124] and hydrotropic sodium tosylate (NaOTs) [125] are another type of catalysts used for the epoxidation of chalcones with an excellent yield (90-95%). In some conditions, H 2 O 2 could only produce cinnamic acid instead of epoxide in acetonitrile [126].…”

Hybrid Alginate–Brushite Beads Easily Catalyze the Knoevenagel Condensation On-Water

“…In continuation of our previous works, − in the present study, we propose the development of a new catalytic system in the form of a microreactor with high-performance catalytic ability under mild conditions for the synthesis of the α,β-unsaturated carbonyl compounds. For this purpose, hybrid xerogel beads (alginate@brushite: Alg@Br) were synthesized via phosphated alginate gelation, and their structural, thermal, and morphological characterizations were studied.…”

Synthesis, Molecular Docking and Antimicrobial Activity of α, β‐Unsaturated Ketone Exchange Moiety for Chalcone and Pyrazoline Derivatives

“…[9] The presence of electron withdrawing moieties (i. e. trifluoromethyl and halogens) with (À COOH) chalcone, however, can potentially reduce the biological activities due to poor solubility and lipophilicity. [6] The unsaturated α,βketo moiety in the chalcone network is also very reactive for the formation of heterocyclic organic chalcone derivatives such as pyrimidine, [10] epoxy chalcone, [11] pyrazoline. [12] Pyrazoline is an eye catching heterocyclic molecule due to the presence of heteroatom nitrogen in cyclic ring, which played marvelous role in the field of medicines (i. e. antiepileptic, [13] antitrypanosomal, [14] antipyretic, [15,16] antioxidant, [17] anti-inflammatory, [18] antimalarial, [19] antihistaminic [20] ) and electronics (e. g. photographic conductor, [21] chemo-sensor [22] and optoelectronic [23] ).…”