Synthesis, Modification, and Application of Mesoporous Materials Based on Mcm-41

The purpose of the investigation carried out in this research work was to synthesize mesoporous materials based on MCM-41 with high surface areas, large pore sizes, narrow pore size distributions, and high thermal, hydrothermal, and mechanical stabilities. This was completed by following the same procedures reported for the fabrication of the MCM-41 but with alterations in the surfactants and the additives used, and the reaction conditions employed such as the pH, the temperature, and aging time. Moreover, we aimed to modify these synthesized mesoporous materials with different functional groups of interest and evaluate their abilities in adsorption and separation of transition and heavy metal ions, and radioactive materials from aqueous medium. The functionalization of these mesoporous materials was done using different methods in order to maximize the number of groups on the surface and inside the pores. Different techniques such as infrared (IR), solid-state 29Si and 13C nuclear magnetic resonance (NMR), X-ray powder diffraction (XRD), thermal gravimetric analyses (TGA), and scanning and transmission electron microscopes (SEM and TEM) were used to confirm the production of the desired products. The surface area, pore size and pore size distribution were determined using the surface area analysis (BET) method. The surface properties (e.g., number of groups on the surface) of these materials were determined by the adsorption of a proper probing molecule. The adsorption and separation abilities of these modified materials for the transition and heavy metal ions, and radioactive materials in aqueous solution were performed in the pH range from 2 to 8 at room temperature. The equilibrium concentration of the metal ions were determined using lead analysis test kit for the lead and using ultraviolet-visible (UV-Vis), inductive couple plasma (ICP), and atomic absorption spectroscopy (AAS) for the rest of materials.Findings and Conclusions: The synthesized mesoporous materials possess high surface areas, large pore sizes, narrow pore size distributions, and high thermal, hydrothermal, and mechanical stabilities. The modified mesoporous materials were found to have high selectivity and capacity in the adsorption and separation of the transition and heavy metal ions in the aqueous solution. In addition, they showed great selectivity and capacity for the adsorption and separation of the radioactive materials in aqueous medium.Chemistry Departmen

catena-Poly[diquinolinium [[diaqua­cobaltate(II)]-μ-cyclo­tetra­phosphato] hexa­hydrate]

The cyclo­tetra­phosphate anion, [P4O12]4−, forms the title complex with cobalt(II) and quinolinium, {(C9H8N)2[Co(P4O12)(H2O)2]·6H2O}n. In the complex anion, the CoII ion, lying on an inversion center, is surrounded by four phosphate O atoms and two water mol­ecules in a slightly distorted octa­hedral geometry. The crystal structure consists of anionic ribbons of formula {[Co(P4O12)(H2O)2]2−}n extending along [100]. A network of O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds consolidates the crystal packing

A Facile and Convenient Synthesis of some Novel Hydrazones, Schiff’s Base and Pyrazoles Incorporating Thieno[2,3-b]thiophenes

A facile and convenient synthesis of some novel hydrazones, schiff’s base and pyrazoles from thieno[2,3-b]thiophene derivatives 1 have been achieved in high yields assisted by microwave and classical methods. The structures of all the title compounds have been elucidated by elemental analysis, IR, MS, 1H-NMR and 13C-NMR. Generally, these findings represent a new class of sulfur and nitrogen moieties that should also be of interest as new materials

Method for the fast determination of bromate, nitrate and nitrite by ultra performance liquid chromatography–mass spectrometry and their monitoring in Saudi Arabian drinking water with chemometric data treatment

A rapid, sensitive and precise method for the determination of bromate (BrO3(-)), nitrate (NO3(-)) and nitrite (NO2(-)) in drinking water was developed with Ultra performance Liquid Chromatography-Mass Spectrometry (UPLC-ESI/MS). The elution of BrO3(-), NO3(-) and NO2(-) was attained in less than two minutes in a reverse phase column. Quality parameters of the method were established; run-to-run and day-to-day precisions were <3% when analysing standards at 10µgL(-1). The limit of detection was 0.04µg NO2(-)L(-1) and 0.03µgL(-1) for both NO3(-)and BrO3(-). The developed UPLC-ESI/MS method was used to quantify these anions in metropolitan water from Saudi Arabia (Jeddah, Dammam and Riyadh areas) and commercial bottled water (from well or unknown source) after mere filtration steps. The quantified levels of NO3(-) were not found to pose a risk. In contrast, BrO3(-) was found above the maximum contaminant level established by the US Environmental Protection Agency in 25% and 33% of the bottled and metropolitan waters, respectively. NO2(-) was found at higher concentrations than the aforementioned limits in 70% and 92% of the bottled and metropolitan water samples, respectively. Therefore, remediation measures or improvements in the disinfection treatments are required. The concentrations of BrO3(-), NO3(-) and NO2(-) were mapped with Principal Component analysis (PCA), which differentiated metropolitan water from bottled water through the concentrations of BrO3(-) and NO3(-) mainly. Furthermore, it was possible to discriminate between well water; blend of well water and desalinated water; and desalinated water. The point or source (region) was found to not be distinctive

Reactivity of Heteropolymolybdates and Heteropolytungstates in the Cationic Polymerization of Styrene

The two heteropolyacids H3PW12O40 and H3PMo12O40, and their homologous salts (NH4)3PW12O40, and (NH4)3PMo12O40 were prepared and tested in the cationic polymerization of styrene. The results showed that the heteropolytungstates were more reactive than the heteropolymolybdates. It has been found that the yield and the viscosity averagemolecular weight (Mv) of polystyrene are directly proportional to the acidity strength of the heteropolyanions (H3PW12O40 &gt; H3PMo12O40 &gt; (NH4)3PW12O40 &gt; (NH4)3PMo12O40). The highest yield (68.0%) and Mv (7,930) were obtained by using H3PW12O40. In addition, H3PW12O40 polymerized the styrene under mild conditions and was recyclable, and could behave as a truly heterogeneous catalyst

Gas-Phase Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide Over Co1.5PW12O40 Keggin-Type Heteropolyanion

The reactivity of Co1.5PW12O40 in the direct synthesis of dimethyl carbonate (DMC) from CO2 and CH3OH was investigated. The synthesized catalyst has been characterized by means of FTIR, XRD, TG, and DTA and tested in gas phase under atmospheric pressure. The effects of the reaction temperature, time on stream, and methanol weight hourly space velocity (MWHSV) on the conversion and DMC selectivity were investigated. The highest conversion (7.6%) and highest DMC selectivity (86.5%) were obtained at the lowest temperature used (200 °C). Increasing the space velocity MWHSV increased the selectivity of DMC, but decreased the conversion. A gain of 18.4% of DMC selectivity was obtained when the MWHSV was increased from 0.65 h-1 to 3.2 h-1

Keggin-Type Heteropolyacid for Ring-Opening Polymerization of Cyclohexene Oxide: Molecular Weight Control

Polymerization of 1,2-cyclohexene oxide (CHO) in dichloromethane was catalyzed by 12-tungstophosphoric acid (H3PW12O40·13H2O) as a super solid acid. The effect of polymerization parameters such as reaction time, temperature, and catalyst amount was investigated. The effect of acetic anhydride as a ring-opening agent was also investigated. The resulting poly(1,2-cyclohexene oxide) (PCHO) was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy (1HNMR), gel-permeation chromatography (GPC), and differential scanning calorimetry (DSC). It has been found that the PCHO prepared over H3PW12O40·13H2O has a stereoregularity higher than that prepared over clay and Aluminium alkoxide catalysts. The Tg value obtained is due to the microstructure but not to molecular weight. The yield and the molecular weight of the polymer depend strongly on the reaction conditions. Molecular weights can be readily controlled by changing reaction temperature, reaction time, and catalyst amount. Contrary to most polymerization reactions, the molecular weight increases with the temperature increase. Addition of acetic anhydride to the reaction medium increased the yield threefold

A Facile One-Pot Synthesis of α-Bromo-α,β-unsaturated Esters from Alcohols

Treatment ofN-bromosuccinimide (NBS) with (carboethoxymethylene) triphenylphosphorane (1) in CH2Cl2 followed by the addition of an alcohol in the presence of manganese dioxide under ultrasonic irradiation constitutes a stereoselective one-pot procedure for the preparation of Z-configured α–bromo-α,β-unsaturated esters in good to excellent yield

A Practical Chemo-enzymatic Approach to Highly Enantio-Enriched 10-Ethyl-7,8-dihydro-γ-ionone Isomers: A Method for the Synthesis of 4,5-Didehydro-α-Ionone

Abstract: An efficient and convenient strategy for the enantioselective synthesis of enantiomerically enriched 10-ethyl-7,8-dihydro-γ-ionone isomers (R)-(+)-7, and (S)-(−)-7 are described utilizing a lipase mediated resolution protocol, and reductive elimination of the secondary allylic alcohol as the key step. The enantioselective and diastereoselective lipase kinetic acetylation of 4-hydroxy-γ-ionone derivatives 6a afforded the 4-acetyl-γ-ionone derivatives (−)-8, and the 4-hydrox-γ-ionone derivatives (+)-6a, which are suitable precursors of the desired products. Stereospecific palladium-mediated elimination of allylic acetate provides the target compounds with an excellent enantiomeric excess and yield. Additionally, the novel 4,5-didehydro-α-ionone 13 is obtained from readily prepared (2,6,6-trimethylcyclohexa-2,4-dien-1-yl) methanol 9. The structures of all newly synthesized compounds have been elucidated by 1 H, 13 C NMR, GC-MS, and IR spectrometry. These compounds represent a new class of odorants that may be of pivotal relevance in industrial perfumery

Green synthesis of iron nano-impregnated adsorbent for fast removal of fluoride from water

Iron nano-impregnated adsorbent was synthesized, characterized and applied for fluoride subtraction from the water. Maximum fluoride removal (90%) was at 4.0 mg/L concentration, 25.0 min. contact time, 7.0 pH, 2.5 g/L dose and 293 K temperature. Iron nanocomposite adsorbent was selective for fluoride removal. The experimental data obeyed Langmuir, Freundlich and Temkin models. The values ΔG° were - 1.89, - 0.86 and - 0.74 kJ/mol at 293, 298 and 303 K temperatures. ΔH° value was - 7.61 kJ/mol; indicating exothermic adsorption. ΔS° value was - 2.30 x 10- 2 kJ/mol K; a signal of entropy decrease during adsorption. The adsorption process was in the order of 293 > 298 > 303 K. Kinetic modeling confirmed pseudo-first-order and liquid film diffusion mechanisms. The mechanism of adsorption is also determine