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In this work, a chain of reactions has been proposed as a new heterogeneous technique, based on the use of natural treated clays as an environmentally friendly catalysts for the synthesis of poly(1,4-bis(methacryloyl)piperazine). We first synthesized the monomer; 1,4-bis(methacryloyl)piperazine (NBMP) in bulk (without solvent) by the condensation o...
Citations
... Its aluminum/silicon portion is relatively higher when compared to other world clays [30]. The chemically activated Maghnite has shown a large catalytic capacity, which has enabled it to be used in a large number of polymerization reactions, published by the polymer chemistry laboratory of the University of Oran in Algeria [31][32][33]. ...
... The increase in basal spacing corresponding to the space of montmorillonite layers; from 10.5 Å in raw-Maghnite to 15.02 Å in Maghnite-H + [10] was reflected by the shift of the montmorillonite peak towards the small values of θ (8.41° to 5.87°) [36]. This is explained by the replacement of interlamellar ions such as Mg 2+ and Ca 2+ by gigantic hydronium ions of the relatively large molecular radius [31]. In general, we note that acid treatment of Maghnite increased basal spacing of montmorillonite, but did not affect the original Maghnite structure, which was confirmed by the absence of the appearance or disappearance of peaks in XRD spectrum of Maghnite-H + . ...
Although the use of conductive polymers has invaded the electronics industry, the insolubility parameter presents a major problem against their direct application on the surfaces of materials. Attachment of cyclic compounds to polymer chains is recommended to increase the solubility of conductive polymers. The aim of this study is to synthesize a new type of intrinsic conductive polymer, soluble in common solvents. The technique is based on the copolymerization of thiophene with a synthesized monomer phenylazepane-2-one. The reaction was catalyzed by a solid catalyst, prepared by the acid treatment of natural clay, generating active sites responsible for the adhesion of the thiophene and benzene rings. Proton and carbon nuclear magnetic resonances (1 H NMR/ 13 C NMR), ultraviolet spectroscopy (UV-Visible), infrared spectroscopy (IR) and differential scanning calorimetry (DSC) were used to identify the material obtained poly [(phenylazepane-2-one)-co-(thiophene)] abbreviated poly (PAT). Thermogravimetric analysis (TGA) showed the thermal stability of poly (PAT) before 200 °C. The solubility of poly (PAT) has been tested and confirmed in various common solvents. The indirect bandgap was calculated at 1.12 eV using Tauc formula. Ac electrical conductivity and dielectric permittivity have been studied versus frequency and temperature, showing the semiconductor character of poly (PAT). The results obtained showed that this novel polymer can play a pioneering role to replace conventional insoluble conducting polymers.
... Maghnite has been chemically modified by the Polymer Chemistry Laboratory team at the University of Oran in Algeria, giving it a catalytic appearance. This has made it used as a catalyst in several polymerization reactions [26][27][28][29] and also as a catalyst/reinforcement for the synthesis of nanocomposite materials [30]. ...
An effective technique is proposed in this study to synthesize a novel polymer, based on the copolymerization of pyrrole with a synthesized monomer (phenylazepane-2-one), combining the character of both conductivity and solubility. The reaction was cationically catalyzed, using an acid exchanged clay (Maghnite-H⁺) as an ecological catalyst. The reaction synthesis of poly[(phenylazepane-2-one)-co-(pyrrole)] abbreviated poly(PAP) has been carried out in dichloromethane. The reaction yield was 85% at a temperature of 25 °C for 4 h using 4% of catalyst. Chemical structures have been characterized by proton and carbon nuclear magnetic resonance (¹H-NMR and ¹³C-NMR), ultraviolet/visible spectroscopy (UV–Vis) and Fourier transform infrared spectroscopy (FT-IR). Thermal properties have been evaluated by differential scanning calorimetry and thermal gravimetric analysis, showing the thermal stability of the poly(PAP) up to 333 °C. Solubility tests confirmed the solubility of poly(PAP) in various common solvents. The indirect band-gap was found 1.22 eV using Tauc’s formula. The semiconductor behavior poly(PAP) has been proven by the evolution of ac electrical conductivity and dielectric properties as a function of frequency and temperature. These new properties allow direct application of poly(PAP) on all desired surfaces rather than conventional materials.
Graphic abstract
... This catalyst was developed in Polymer Chemistry Laboratory «LCP»[. [30][31][32][33][34], it has shown remarkable catalytic capabilities in polymerization reactions of various vinyl and heterocyclic monomers. The new catalyst Maghnite-H + was prepared according to the process reported in our previous study . ...
The overall objective of this study is to synthesize ammonium salts by adding dihalogenated compounds such as dibromides and dichlorides to aniline using the green catalyst "Maghnite-H + ", a new non-toxic catalyst. The important part of this work consisted of carrying out the formation of these ammonium salts under suitable conditions without solvent, at room temperature, for different durations and using several catalyst contents. The effect of time and amount of catalyst on the yield of the addition reactions was studied. All the synthesized products were characterized by IR spectroscopy, 1 H-NMR and 13 C-NMR.
... This catalyst was developed in Polymer Chemistry Laboratory «LCP»[. [30][31][32][33][34], it has shown remarkable catalytic capabilities in polymerization reactions of various vinyl and heterocyclic monomers. The new catalyst Maghnite-H + was prepared according to the process reported in our previous study . ...
The overall objective of this study is to synthesize ammonium salts by adding dihalogenated compounds such as dibromides and dichlorides to aniline using the green catalyst "Maghnite-H + ", a new non-toxic catalyst. The important part of this work consisted of carrying out the formation of these ammonium salts under suitable conditions without solvent, at room temperature, for different durations and using several catalyst contents. The effect of time and amount of catalyst on the yield of the addition reactions was studied. All the synthesized products were characterized by IR spectroscopy, 1 H-NMR and 13 C-NMR.
... Isatin derivatives (10)were synthesized viamannich reaction of isatin(7) with monosubstituted piperazines (8)by the employment of aqueous formaldehyde (9). Derivatives (10)werefurther converted into isoindigo derivatives(11) by employing tris(diethylamino)phosphine in dichloromethane at À60 to 20 C [5]. (Scheme 2) ...
... The prepration of monomer (24) began by the condensation of piperazine(13) with compound (23)under the influence of maghnite-H þ at 5 C for 2 h along with the release of water molecule (25). For the prepration of poly(1,4-bis(methacryloyl)piperazine)(26), the monomer (24) underwent anionic polymerization by employing maghnite-Na þ as a catalyst at 0 C for 24 h [10]. (Scheme 7) ...
Piperazine is two nitrogen containing heterocyclic compound. The fundamental activity of the piperazine is due to the 1,4-position of nitrogen atoms and their substitutions. The SN1 reaction is followed by the others alkylation and substitution reactions. Substituted piperazine derivatives hold an important position for the development of crucial drugs. They exhibit a broad spectrum of biological activities e.g. antitubercular, antibacterial, anti-inflammatory, anticancer, antiviral, antidiabetic and antimalarial. Immense numbers of biological activities dis-played by disubstituted piperazine derivatives are due to the presence of two nitrogen atoms in the ring. Keeping in mind their biological activity profile, a series of novel 1,4-substituted piperazine synthesized derivatives were collected. All the prepared derivatives are expected to show different biological activities particularly enzyme inhibition activities against α-Amylase.
The slow degradability of aliphatic polyesters can be attributed to their poor hydrophilicity. In this article, we report on a series of biodegradable and biocompatible pH‐responsive piperazine‐based copolyesters labeled P2‐P7 synthesized by melt polycondensation approach that exhibit tunable hydrophilicity with antibacterial properties. X‐ray diffraction analysis showed the copolymers to be highly crystalline, with their crystallinity in the range of 41%–55%. Contact angle measurements showed moderate hydrophilicity, with a water contact angle of 59°–71° for P2‐P7 suggesting that the incorporation of piperazine units in the copolymer backbone moderately improves their hydrophilicity. N‐alkylation with methyl iodide further enhanced their hydrophilicity with their measured contact angles changing from 62° in unalkylated P2 to 27° in the fully alkylated analogue P12. The effect of crystallinity and hydrophilicity on polyester degradation was systematically investigated by hydrolytic degradation studies. The quaternized copolymer P10 showed ~39% reduction in molecular weight, whereas only ~19% of P2 was degraded in 8 weeks, thus exhibiting faster degradation in the quaternized polyester. The biocompatibility with U2OS cells and the antibacterial properties established their importance as potential biomedical materials.
A new synthesis of poly[(2,5-diyl pyrrole)(4-hydroxy-3-methoxy benzylidene)] copolymer was achieved via the polycondensation of vanillin and pyrrole in bulk and in solution using CH2Cl2 as solvent with acid exchanged montmorillonite clay called Maghnite-H+, a green catalyst initiator, non-toxic and recoverable by simple filtration. The effects of several parameters, such as the amount of catalyst, time and temperature of the polymerization and molar ratio of monomers on the polymers yield were studied. The conjugated polymer was characterized by means of 1H NMR, Fourier transform infrared spectroscopy and UV–Visible spectroscopy, as well as X-ray diffraction. The thermal properties of the prepared polymers were studied by thermogravimetric analysis. Poly[(2,5-diyl pyrrole)(4-hydroxy-3-methoxy benzylidene)] was found to be a semiconductive polymer.
In this article, we report on a new class of biodegradable piperazine-based aliphatic pH-responsive polyesters with tunable hydrophilicity. The aliphatic polyesters PC1-PC4 with high thermal stability up to 340 ℃ were synthesized by polycondensation of dimethyl 2,2’-(piperazin-1,4-diyl)diacetate with a series of alkane diols (C4 to C10). The resulting polyesters are found to be highly crystalline with ∼47-55% crystallinity as estimated from XRD and moderately hydrophilic as the water contact angle was found to be in the range of 63° - 72°. An N-alkylation or protonation approach was used to tune their crystallinity and hydrophilicity so as to enhance biodegradability. Upon quaternization with methyl iodide, a significant effect on functional and structural properties was observed with reduced crystallinity and enhanced hydrophilicity, as the contact angle decreased down to 24° upon methylation. The pH-responsive nature of the material was evaluated with zeta potential measurements, and the surface charge increased up to +41.4 mV with a more positive charge on the polymer backbone at pH 2 for polyester PC2. Further, microbial and hydrolytic degradation studies showed that the quaternized polyesters PC6 and PC9 exhibit faster degradation when compared to their parent polymer PC2, demonstrating their significance as a new class of biodegradable polyesters.
Clays and modified or supported clays have become some of the widely used catalysts for a variety of organic reactions, due to their easy structural modifications and activation, low-cost, eco-friendly nature, ready availability, ability to act as acidic or basic catalyst without being corrosive. The present review is a survey of the literature dealing with most of the important work on clay catalysed organic reactions published during the period 2011–2020, and is a sequel to our previous review covering the literature of 2001–2010. The review consists of various segments starting with introduction that briefly mentions the structure and modification of clay minerals, particularly the most widely used montmorillonite, followed by organic reactions such as condensation, addition, substitution, elimination, reduction, oxidation, wastewater remediation, biodiesel synthesis and a few miscellaneous reactions that are accomplished using these catalysts. Among these, biodiesel synthesis and remediation are widely investigated transformations, and find practical applications.
Graphical Abstract
In the present work, we have developed an original method to synthesize and to polymerize N-alkyl methacrylamide monomers with a new chemical approach by using an heterogeneous catalyst “Maghnite Na⁺” as green and recyclable catalyst in one step with respect to the green chemistry principals. The polymerization of N-alkyl methacrylamide monomers was carried out using an environmentally friendly catalyst, during which the monomers were synthesized at room temperature for 2 h by reacting an amino derivative (heterocyclic and aryl amine) with methacrylic anhydride in presence of “Maghnite H⁺” a green catalyst in a bulk (without solvent). The undertaken green reaction has yielded 85% of conversion and 100% selectivity of the obtained product, and contributed to substitute former used toxic reactant methacryloyl chloride and triethylamine, frequently used in previous published studies. Infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy ¹H and ¹³C subjected the monomers and polymers structures to confirmation.
