Efficient Removal of Cobalt(II) and Strontium(II) Metals from Water using Ethylene Diamine Tetra‐acetic Acid Functionalized Graphene Oxide

Graphene oxide (GO) with high specific surface area was prepared and functionalized with ethylene diamine tetra‐acetic acid (EDTA). The as‐prepared GO and the functionalized one (GO‐EDTA) were characterized using high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), and Raman spectroscopy. The as‐prepared and EDTA funcationalized GO were applied as adsorbent to remove strontium(II) and cobalt(II) from water. The results indicated that the prepared materials are efficient adsorbents for strontium(II) and cobalt(II) removal. The adsorption of Co^II and Sr^II under effects of contact time, temperature, and pH was investigated It is concluded that the maximum adsorption capacities of GO for Co^II and Sr^II were about 168 and 140 mg · g^–1, whereas of GO‐EDTA the values were about 197 and 158 mg · g^–1, respectively. It is indicated that pH 6 and temperature 40 °C are the best condition for Co^II and Sr^II removal from water. The application of Langmuir and Freundlich isotherms indicated that Langmuir isotherm is best fit for Co^II and Sr^II equilibrium adsorption. Adsorption kinetics were studied by applying pseudo first‐order, pseudo second‐order, and intraparticle diffusion models on the experimental data. The results proved that pseudo second‐order model is the best represented adsorption kinetics. Appling the intraparticle diffusion regressions on the experimental data indicated that intraparticle diffusion involved in adsorption process, which was not the only rate‐controlling step.     

A Study on the extraction of uranium(VI) from sulphate leach liquor using LIX63

The sulphate leach liquor obtained from the sulphuric acid leaching process of Egyptian monazite was treated using solvent extraction to recover U(VI) by LIX63. The influence of various basic variables such as pH, concentration of LIX63, temperature, different stripping agent, phase ratio and diluents was examined. Using 10% LIX63 with the aqueous solution at equilibrium pH 5.5 and a phase ratio A/O?=?1/1, a four-stage McCabe-Thiele plot was constructed, which showed 85.57% of U(VI) extraction. The thermodynamic data showed that the extraction process is exothermic with enthalpy change ΔH?=???43.866?kJ/mol, the stripping of U(VI) was quantitative using 4?M HNO₃. The stable complex UO₂(HSO₄)R_org formed during extraction which supports the cation exchange mechanism was confirmed by FTIR spectral analysis. Uranium cake was finally obtained from the strip solution by the addition of hydrogen peroxide and ammonium hydroxide as precipitating agents, and a workable flowsheet was then formulated.     

Design,Synthesis, and Antioxidant/Antidiabetic Activity of Nucleic Acid Bases Bearing Fused N,S‐Heterocyclic Phosphor Esters

Reactions of unsaturated and saturated Wadsworth–Horner–Emmons reactants with N¹‐ and N³‐allyl‐2‐thiouracils, under phase‐transfer catalysis conditions, resulted in the respective N‐bridged thiazolo‐, pyrrolo‐, and thiazino‐phosphor esters. Products were obtained via the regioselective attack of the Wadsworth–Horner–Emmons reagent on the allylic‐1′‐C in tandem of double bond migration processes, followed by a series of transformations. Synthesis of pyrimidin‐1(2H, or 6H)‐yl)but‐1‐ene‐1,1‐diyldiphosphonates was also described. On the basis of the prediction results (PASS program, Moscow, Russia; free available internet version of PASS 2009.1: http://www.ibmc.msk.ru/PASS ), we further estimated the antioxidant and antidiabetic activities of the synthesized compounds. The results showed that all compounds cause moderate to good antidiabetic activities. However, the thiazolophosphonates exhibited the highest inhibitory antioxidant activity; nevertheless, the diphosphonates manifested the best protective effects against DNA damage induced by bleomycin. Biological testing confirmed the results of computational modeling.     

Synthesis of Some New Fused and Binary 1,3,4‐Thiadiazoles as Potential Antitumor and Antioxidant Agents

Annulations of 2‐amino‐1,3,4‐thiadiazole ( 1 ) with α,β‐unsaturated carbonyl compounds 2 , 5 , and 9 afforded thiadiazolo[3,2‐a]pyrimidin 3 , benzamide 7 , and bis‐pyrazole derivative 11 . Cyclization of benzamide 7 with POCl₃ gave binary imidazole derivative 8 . Moreover, alkylation of 1 with 2‐bromo‐1‐(2H‐chromen‐3‐yl) ethanone ( 9 ) followed by cyclization gave imidazo[2,1‐b]‐1,3,4‐thiadiazole derivative 15 . Multicomponent reaction of 1 with heterocyclic and/or aromatic aldehyde and thioglycolic acid afforded the corresponding thiazolidinones 17 and 19 . Finally, a one‐pot synthesis of 1 with isatin and thiosemicarbazide furnished the spirotriazole 20 . The newly synthesized compounds were evaluated as antitumor agents.     

Investigations of the Chemistry of Alkyl Phosphites Toward Nitrogen-Containing Compounds: Efficient Approaches to α-Amino-, β-Amino-, and/or Enaminophosphonates

Abstract

In this study, we report recent investigations of the chemical reactivity of alkyl phosphites, mainly trialkyl and dialkyl phosphites, with molecules containing different nitrogen-containing compounds reported by us and other research groups over the past 25 years. Previous ground-breaking important reports are also considered. The reviewed investigations in this article are grouped according to only the type of the nitrogen-functional groups [amines (primary, secondary, and tertiary amines), imines, amides, thioamides, nitriles, isocyanates, isothiocyanates, oximes, hydrazones, diazo, and azides] and not according to the site of attack or the final products. Furthermore, the present review article focuses on the synthesis of α-amino-, β-amino-, and/or enaminophosphonates. These compounds have important roles in pharmaceutical chemistry.     

Remarkably Efficient and Direct Route to Quinolines and Benzoazepines from the Condensation of Benzoxazinediones with Phosphonium Carbanion Salts

Treatment of 2H‐3,1‐benzoxazine‐2,4(1H)‐dione (1a) with vinyltriphenylphosphonium bromide (2a) gives substituted benzoazepine 8a (48% yield) and indolizinone 12 (27% yield), whereas substituted quinolinone 15 and benzoazepine 8b were isolated from the reaction of N‐methylisatoic anhydride (1b) and 2a. Furthermore, a series of quinoline derivatives was synthesized from the reactions of 1a and 1b with allyl‐(2b), alkyl‐(2c), (2d), and cyanomethyl‐(3) triphenylphosphonium salts.     

Labeling and biodistribution of 99mTc-7-bromo-1,4-dihydro-4-oxo-quinolin-3-carboxylic acid complex

7-Bromo-1,4-dihydro-4-oxo-quinolin-3-carboxylic acid (BDOQCA), was synthesized with a yield of 93% and well characterized. The obtained compound was investigated to label with one of the most important radioactive isotopes (technetium-99m). Effect of BDOQCA concentration, stannous chloride dihydrates (SnCl₂.2H₂O) concentration, pH and reaction time on the percent labeling yield of ^99mTc-BDOQCA complex was studied in details. ^99mTc-BDOQCA complex was obtained at a maximum yield of 97.3% by mixing 2.5 mg of BDOQCA with 25 μg SnCl₂.2H₂O at pH 6 and 30 min reaction time and the formed complex was stable for a time up to 8 h with a maximum yield of 97.3%. Biodistribution studies in mice were carried out using experimentally induced infection in the left thigh using E. coli. Both thighs of the mice were dissected and counted to evaluate the ratio of bacterial infected thigh/contralateral thigh. Higher uptake in the infected thigh was observed after 2 h of IV administration of ^99mTc-BDOQCA complex (T/NT = 7.6 ± 0.6%) than that of the commercially available ^99mTc-ciprofloxacin complex (T/NT = 3.8 ± 1%). The in vitro binding and biodistribution of ^99mTc-BDOQCA complex in the septic and aseptic inflammation bearing mice showed that, ^99mTc-BDOQCA complex is a promising agent for infection imaging and can differentiate between infected and inflamed muscle.     

FUSED PHOSPHONO SUBSTITUTED O-, AND N-HETEROCYCLES via CONDENSATIVE CYCLISATION REACTIONS OF α-PHOSPHONYL CARBANIONS WITH 4-THIAZOLIDINONES

Phosphono substituted-thiazolones 5a, b together with fused phosphono-pyran-5-ones 9a, b and the diolefins 8a–d were regioselectively prepared in reasonable yields from the reactions of 5-arylidene-4-thiazolidinones 1a, b with phosphonoacetates 2a, b. Conversely, Michael addition products 11a, b (～30%) along with the phosphono substituted-thiazole derivatives 12a, b (～33%) were obtained from treating 1a, b with cyanomethylenephosphonates (2c). The reactions of 1a, b with vinylphosphonate 2d proceeded with phase-transfer catalysis, yielding the corresponding 2-thioalkyl-derivatives 14a, b and phosphonates 13a, b.     

Action of Nucleophilic Phosphorus Reagents on Heterocyclic cis-Disulfides

As a contribution to previous studies of the reaction of phosphorus nucleophiles with heterocyclic cis-disulfides,^1,2 the reactivity of trialkyl phosphites 2 toward 5-p-chlorophenyl-4-cyano-1,2-dithiol-3-thione 1a, 5-phenyl-1,2,4-dithiazol-3-thione 1b and its 3-carbonyl derivative 1c has now been investigated.