Chemical properties of complex aluminum ions

The objective of this research work was to study the synthesis of metallic salts and to analyze their properties. For this purpose, tests were carried out using basic and acid solutions. These tests allowed to identify that the reaction of aluminum in the presence of sulfuric acid is an exothermic reaction whose first stage is the formation of the tetrahydroxoaluminate (III) ion complex, a process in which a significant amount of heat is released from the system and a large amount of hydrogen gas for the oxidation of aluminum, a second stage in which sulfuric acid was added to neutralize the basicity of the solution transforming the complex into disulfate-aluminate (III), Then a third stage consisted in subjecting the solution in an ice bath to decrease the solubility of the complex and the formation of whitish crystals and finally the removal of excess crystals by washing with ethanol, these tests revealed the importance of excess sulfuric acid in the stabilization of the aluminate ion and the ease of the complex ion to bind to water molecules, thus determining important properties of the reaction as the type, orientation, solubility and the intermediates affected by the metal catalysis.

Enhancement of EPDM Crosslinked Elastic Properties by Association of Both Covalent and Ionic Networks

The objective of this study was to replace elastomer crosslinking based on chemical covalent bonds by reversible systems under processing. One way is based on ionic bonds creation, which allows a physical crosslinking while keeping the process reversibility. However, due to the weak elasticity recovery of such a physical network after a long period of compression, the combination of both physical and chemical networks was studied. In that frame, an ethylene-propylene-diene terpolymer grafted with maleic anhydride (EPDM-g-MA) was crosslinked with metal salts and/or dicumyl peroxide (DCP). Thus, the influence of these two types of crosslinking networks and their combination were studied in detail in terms of compression set. The second part of this work was focused on the influence of different metallic salts (KOH, ZnAc2) and the sensitivity to the water of the physical crosslinking network. Finally, the combination of ionic and covalent network allowed combining the processability and better mechanical properties in terms of recovery elasticity. KAc proved to be the best ionic candidate to avoid water degradation of the ionic network and then to preserve the elasticity recovery properties under aging.

Laminar N-Doped Carbon Materials from a Biopolymer for Use as a Catalytic Support for Hydrodechlorination Catalysts

Nitrogen-doped porous carbons were prepared using a chitosan biopolymer as both a carbon and nitrogen precursor and metallic salts (CaCl2 and ZnCl2-KCl) as a templating agent with the aim of evaluating their performance as catalyst supports. Mixtures of chitosan and templating salts were prepared by simple grinding subjected to pyrolysis and finally washed with water to remove the salts. The resulting materials were characterized, showing that homogeneous nitrogen doping of carbon was achieved (7–9% wt.) thanks to the presence of a nitrogen species in the chitosan structure. A lamellar morphology was developed with carbon sheets randomly distributed and folded on themselves, creating slit-shaped pores. Substantial porosity was observed in both the micropore and mesopore range with a higher surface area and microporosity in the case of the materials prepared by ZnCl2-KCl templating and a larger size of mesopores in the case of ZnCl2. Catalysts with well-dispersed Pd nanoparticles (around 10 nm in diameter size) were synthesized using the chitosan-based carbons obtained both by salt templating and direct chitosan pyrolysis and tested in the aqueous phase hydrodechlorination of 4-chlorophenol. The fast and total removal of 4-chlorophenol was observed in the case of catalysts based on carbons obtained by templating with CaCl2 and ZnCl2-KCl in spite of the low metal content of the catalysts (0.25% Pd, wt.).

Facile One-Pot Synthesis of PdM (M=Ag, Ni, Cu, Y) Nanowires for use in Mixed Matrix Membranes for Efficient Hydrogen Separation

Palladium and palladium alloy nanowires (PdM; M= Ag, Ni, Cu, Y) of varying compositions were synthesized by facile and scalable one-pot polyol reduction of metallic salts using poly(vinylpyrrolidone) (PVP) as...

Electrochemical sandwich-type immunosensor for detection of PSA based on trimetallic AgAuPt nanocomposite synthesized using galvanic replacement reaction

A sandwich-type electrochemical immunoassay was introduced to the determination of prostate-specific antigen (PSA) biomarker. A direct and simple galvanic replacement reaction was performed between the Ag framework and metallic salts...

Eco-friendly Methods of Natural Dye Extraction from Bark of Ficus religiosa and Their Impacts on Dyeing Technology in Nepal

Plant-based natural dyes are eco-friendly and less allergic to the human body. Different reports on toxicity and allergic reactions that appeared in synthetic dyes cause interest in natural dyes in recent years. The present study focused on the feasibility of aqueous extraction of plant dyes from the bark of Ficus religiosa (Peepal), a historical tree of Hindu culture. Extracted dyes were characterized by ultra-violet visible (UV-Vis) spectroscopy and Fourier transform infrared (FTIR) spectroscopy to reveal the structural and functional confirmation of extracted dye. Dye was used for dyeing fabric using both natural and commercial mordant. Mordants such as lemon juice and metallic salts such as potassium dichromate (K2Cr2O7), copper sulphate (CuSO4.5H2O), and iron sulphate (FeSO4) are used to set extracted dye on cotton fabrics and other fibers. This research aims to find the effectiveness and feasibility study of the use of natural mordant instead of metallic mordant. The use of natural dyeing with natural mordant is very effective for health purpose but found to be expensive.

Toward a New Way for the Valorization of Miscanthus Biomass Produced on Metal-Contaminated Soils Part 2: Miscanthus-Based Biosourced Catalyst: Design, Preparation, and Catalytic Efficiency in the Synthesis of Moclobemide

The conception of two biosourced catalysts (biocatalysts) using stems of miscanthus from the first part of this study are described herein. The temperature and the process used to extract metals from plant as mixture of Lewis acids were investigated in detail and proved to be essential in the design of the biosourced catalysts and their catalytic efficiency. One part of the crude mixture of Lewis acids extracted from the aerial parts of miscanthus plants was used without further treatment as a homogeneous biocatalyst (M1), and the other part was supported on montmorillonite K10 to provide a heterogeneous biocatalyst (MM1). M1 and MM1 were next tested in the synthesis of moclobemide (main ingredient of a drug used to treat depression) and led to excellent yield. Additional comparative experiments with different commercial metallic salts (NaCl, KCl, CaCl2, MgCl2, CuCl2, ZnCl2, FeCl2, FeCl3, MnCl2, and AlCl3) and their mixtures were carried out and underlined the importance of the multimetallic synergy on catalytic activity. Finally, a comparison of this new synthetic method assisted by the biosourced catalyst with the previously described procedures to access moclobemide was realized by calculating their green chemistry metrics. This study revealed that the use of the biosourced catalyst led to one of the greenest synthetic methods described today to produce moclobemide.

α-Ketophosphonates in the Synthesis of α-iminophosphonates

The potentialities of condensation of α-ketophosphonates with primary amines for direct synthesis of α-iminophosphonates have been revealed. Diesters of α-ketophosphonic acids react with the primary amines by two competitive pathways: with a formation of α-iminophosphonates or a C-P bond cleavage resulting in a hydrogen phosphonate and an acylated amine. In many cases, the latter undesirable pathway is dominant, especially for more nucleophilic alkyl amines. Using metallic salts of α-ketophosphonates avoids the C-P bond cleavage, allowing direct preparation of α-phosphorylated imines by the reaction with primary amines. This strategy provides an atom economy single-stage synthesis of iminophosphonates – precursors of bio relevant phosphorus analogs of α-amino acids. Methyl sodium iminophosphonates, bearing aryl or heteryl substituents at the imino carbon atom exist in solutions at room temperature as an equilibrium mixture of Z- and E-isomers. A configuration of the C=N bond can be controlled by the solvent: changing the aprotic dipolar solvent DMSO-d6 by water or alcohols leads to the change from a predominant Z-isomer to almost an exclusive E-form. In contrast, diesters of the respective iminophosphonates exist in non-protic solvents predominantly in Econfiguration. The solvent effect on E-Z stereochemistry is demonstrated by DFT calculations.