Articles de revues : « ECO- FRIENDLY REACTION MEDIA »

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Lusiana, Retno Ariadi, Rahmad Nuryanto, Nor Basid Adiwibawa Prasetya, Resa Putri Sherina et Dilla Dayanti. « Eco-Friendly Chitosan-Based Biodiesel Heterogeneous Catalyst Support Membrane ». Jurnal Kimia Sains dan Aplikasi 26, n^o 2 (20 janvier 2023) : 39–49. http://dx.doi.org/10.14710/jksa.26.2.39-49.

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A chitosan-polyvinyl pyrrolidone K-30 (Cs-PVP.K30) membrane was prepared as a heterogeneous catalyst supporting membrane in the transesterification process in the production of biodiesel from palm oil and methanol through the blend reaction between chitosan (Cs) and polyvinyl pyrrolidone K-30 polymer (PVP K-30). Several membranes were characterized by their physicochemical and catalytic properties. Based on physicochemical data, it was found that including the carbonyl group from PVP K-30 into the chitosan framework correlated with an increase in porosity, hydrophilicity, water absorption, and the degree of swelling of the membrane. The results of the analysis using Fourier Transmittance Infra-red (FTIR) showed the spectra of carbonyl (-C=O) and hydroxyl (-OH) groups at wavenumbers 1648 cm-1 and 3363 cm-1, which shows that the reaction of chitosan alloy with PVP K-30 has been successfully carried out. The catalytic site of the Cs-PVP K30-NaOH membrane in the biodiesel production process was studied under several conversion conditions. It was found that the conversion of biodiesel reached 93.90% with a reaction time of 90 minutes, a temperature of 65°C, and an oil/methanol mole ratio of 1:7.

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Yadav, J. S., et H. M. Meshram. « Green twist to an old theme. An eco-friendly approach ». Pure and Applied Chemistry 73, n^o 1 (1 janvier 2001) : 199–203. http://dx.doi.org/10.1351/pac200173010199.

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Owing to present environmental awareness, attempts are being made toward the evolution of environmentally benign processes using solid-supported reagents and microwave-assisted reactions. A newly developed, nonmetallic oxidative reagent, "clayan", has been exploited for various reactions such as deprotection, oxidation, oxidative coupling, and nitration and bromination of activated and deactivated arenes. In another green chemistry endeavor, reactions such as reduction and cyclization have been successfully carried out in dry media under microwave irradiation. The nonsolvent reaction, experimental simplicity, and enhanced selectivity are the main attractive features of the approach.

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Eshetu, Gebrekidan Gebresilassie, Michel Armand, Hiroyuki Ohno, Bruno Scrosati et Stefano Passerini. « Ionic liquids as tailored media for the synthesis and processing of energy conversion materials ». Energy & ; Environmental Science 9, n^o 1 (2016) : 49–61. http://dx.doi.org/10.1039/c5ee02284c.

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Radatz, Cátia Schwartz, Liliana do Amaral Soares, Estéfano Roberto Vieira, Diego Alves, Dennis Russowsky et Paulo Henrique Schneider. « Recoverable Cu/SiO2 composite-catalysed click synthesis of 1,2,3-triazoles in water media ». New J. Chem. 38, n^o 4 (2014) : 1410–17. http://dx.doi.org/10.1039/c3nj01167d.

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Shim, Jae Ho, Seok Hyun Cheun, Hyeon Soo Kim et Deok-Chan Ha. « Enantioselective Organocatalyzed Michael Addition of Isobutyraldehyde to Maleimides in Aqueous Media ». Molecules 27, n^o 9 (25 avril 2022) : 2759. http://dx.doi.org/10.3390/molecules27092759.

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Thiourea was introduced into (R,R)-1,2-diphenylethylenediamine as an organocatalyst to promote the reaction between isobutyraldehydes and maleimides. Enantioselective Michael addition reaction was carried out as an eco-friendly method using water as the solvent. As a result of the reaction between isobutyraldehyde and maleimide, ≥97% yield and 99% enantioselectivity were obtained at a low catalyst loading of 0.01 mol%. The solvent effect can be explained by theoretical calculations that indicate the participation of a transition state, in which the CF3 substituent of the catalyst is a hydrogen bond activated by the surrounding water molecules. This discovery enabled the use of low catalyst loading in the organic reactions of chiral substances for pharmaceutical applications. Furthermore, a solvent effect for Michael reaction of the organocatalysts was proposed, and the organic reaction mechanisms were determined through quantum calculations.

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Shim, Jae Ho, Seok Hyun Cheun, Hyeon Soo Kim et Deok-Chan Ha. « Enantioselective Organocatalyzed Michael Addition of Isobutyraldehyde to Maleimides in Aqueous Media ». Molecules 27, n^o 9 (25 avril 2022) : 2759. http://dx.doi.org/10.3390/molecules27092759.

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Thiourea was introduced into (R,R)-1,2-diphenylethylenediamine as an organocatalyst to promote the reaction between isobutyraldehydes and maleimides. Enantioselective Michael addition reaction was carried out as an eco-friendly method using water as the solvent. As a result of the reaction between isobutyraldehyde and maleimide, ≥97% yield and 99% enantioselectivity were obtained at a low catalyst loading of 0.01 mol%. The solvent effect can be explained by theoretical calculations that indicate the participation of a transition state, in which the CF3 substituent of the catalyst is a hydrogen bond activated by the surrounding water molecules. This discovery enabled the use of low catalyst loading in the organic reactions of chiral substances for pharmaceutical applications. Furthermore, a solvent effect for Michael reaction of the organocatalysts was proposed, and the organic reaction mechanisms were determined through quantum calculations.

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Bhatt, Nikita, Smriti, Richa Khare et Monika Kamboj. « Suzuki-Miyaura Cross Coupling Reaction in Various Green Media ». Asian Journal of Chemistry 33, n^o 9 (2021) : 1976–84. http://dx.doi.org/10.14233/ajchem.2021.22584.

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Suzuki-Miyaura cross-coupling reaction is an efficient and utilized method for the direct formation of carbon-carbon bonds. The effectiveness and efficiency of Suzuki-Miyaura cross-coupling reaction and its applications have been the topic of interest for synthetic chemists for the last few decades. Green chemistry is the area where we use eco-friendly products. Suzuki coupling includes palladium or nickel catalyzed coupling reaction, which involves ester of boric acids or simply boric acids with the organic halides or pseudohalide. In recent years, these catalytic systems have been developed in a green environment for Suzuki reaction (Suzuki-Miyaura cross-coupling reaction). This review epitomizes the Suzuki-Miyaura cross-coupling reaction using efficient catalysts in various green media.

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Gao, Li Ya, Xue Jun Tan, Wei Xue, Dong Sheng Zhang, Xin Qiang Zhao et Yan Ji Wang. « An Eco-Friendly Catalytic Route for One-Pot Synthesis of Phenols from Aromatics and Hydroxylamine ». Advanced Materials Research 781-784 (septembre 2013) : 163–68. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.163.

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A series of ionic liquids were used as a co-solvent in the reaction of one-pot synthesis of phenols from aromatics and hydroxylamine. Then an eco-friendly catalytic system, i.e., [HSO3-bmi [CF3SO3]-H2O-HAc media with (NH4)6Mo7O24·4H2O catalyst, was designed for the reaction. The results showed that aromatics were successfully hydroxylated to give the corresponding phenols. Recycling experiments suggested that the catalytic system was stable enough to be recycled.

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Rehman, Khalil ur, Shaista Airam, Long Song, Jian Gao, Qiang Guo, Yukun Xiao et Zhipan Zhang. « MnS-Nanoparticles-Decorated Three-Dimensional Graphene Hybrid as Highly Efficient Bifunctional Electrocatalyst for Hydrogen Evolution Reaction and Oxygen Reduction Reaction ». Catalysts 10, n^o 10 (3 octobre 2020) : 1141. http://dx.doi.org/10.3390/catal10101141.

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The search for renewable energy resources has attracted considerable research interests in electrochemical reactions of hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) that are essential for fuel cells. Earth-abundant, eco-friendly and cost-effective transition metal compounds are emerging candidates as electrocatalysts in these reactions. Herein, we report the growth of manganese sulfide nanoparticles on three-dimensional graphene, through an easy, progressive successive ionic layer adsorption and reaction (SILAR) method, where manganese sulfide nanoparticles (MnS-NPs), diameter of 4–5 nm are homogeneously decorated on the 3D graphene matrix. The formed hybrid shows improved HER activity in 0.1 M KOH when compared to bulk MnS. Moreover, MnS-NPs@3DG is also active in catalyzing ORR, qualifying it as a new type of bifunctional electrocatalyst in alkaline media.

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Naeimi, Hossein, et Vajihe Nejadshafiee. « Efficient one-pot click synthesis of β-hydroxy-1,2,3-triazoles catalyzed by copper(i)@phosphorated SiO2via multicomponent reaction in aqueous media ». New J. Chem. 38, n^o 11 (2014) : 5429–35. http://dx.doi.org/10.1039/c4nj00909f.

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Mohammadi, Seddigheh, Dadkhoda Ghazanfari et Zahed Karimi-Jaberi. « An Efficient, Potassium Carbonate-Catalysed, Three-Component Reaction of Aldehydes, Malononitrile and Amidines Leading to Highly Functionalized Pyrimidines in Aqueous Media ». Letters in Organic Chemistry 17, n^o 4 (25 mars 2020) : 281–86. http://dx.doi.org/10.2174/1570178616666190401190207.

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Various 4-amino-5-cyanopyrimidines were readily prepared in a few minutes with good yields through a one-pot, three-component reaction of aldehydes, malononitrile and amidines in aqueous media in the presence of catalytic amounts of potassium carbonate. Short reaction times, high efficiency, generality of the method, synthesis of new derivatives, inexpensiveness, and non-toxicity of the catalyst/solvent are the interesting features of this method, which make it eco-friendly and highly attractive.

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Jelali, Hamida, A. Chakchouk-Mtibaa, Lasaad Baklouti, Hallouma Bilel, Yaser Bathich, L. Mellouli et Naceur Hamdi. « Development of New Multicomponent Reactions in Eco-Friendly Media-Greener Reaction and Expeditious Synthesis of Novel Bioactive Benzylpyranocoumarins ». Journal of Chemistry 2019 (21 août 2019) : 1–10. http://dx.doi.org/10.1155/2019/8693614.

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Multicomponent cyclocondensation of hydrazine derivatives, ethyl acetoacetate, aromatic aldehydes, and 4-hydroxycoumarin has been reported. The optimization details of the developed novel protocol are recorded. The novel procedure features short reaction time, moderate yields, and simple workup. In addition, BMIM[triflate] was chosen as a green solvent. The structures of the obtained benzylpyrazolyl coumarins were determined and confirmed by 1H NMR, 13C NMR, IR, and elemental analysis. The MIC values of benzylpyrazolyl coumarin derivatives were determined by the microbroth dilution method using 96-well plates. However, the derivatives 5a, 5b, 5d, and 5g possess the strongest activities. Compound 5b was the most active derivative against Candida albicans. Moreover, the antioxidant activity determination of these coumarins derivatives 5(a–g)–6(a–g) were studied with the DPPH and compared with gallic acid (GA)and butylated hydroxytoluene (BHT). Molecular modelling studies using DFT (density functional theory) calculations showed that there two tautomers A and B in which A is more stable than B. The benzylpyrazolyl coumarin derivatives 5e and 6f exhibited the most cytotoxic effect on the promising cytotoxic activity with IC50 values 4.45 μg/mL against MDA-MB-231 and 4.85 μg/mL against MCF7, respectively.

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Ambhore, Ajay N. « Eco-friendly Synthesis of Some New Benzylidene-iminothiazolyl-pyrazol-3-ol Derivatives via One-Pot Multicomponent Reaction and Evaluation of Antioxidant Activities ». Asian Journal of Organic & ; Medicinal Chemistry 6, n^o 4 (31 décembre 2021) : 264–69. http://dx.doi.org/10.14233/ajomc.2021.ajomc-p348.

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In present work, one-pot multicomponent reaction (MCR) route for the synthesis of benzylideneiminothiazolyl- pyrazol-3-ol derivatives (5a-p) by reacting ethyl cyanoacetate (1), substituted benzaldehyde (2a-c), thiosemicarbazide (3) and substituted phenacyl bromide (4a-g). This reaction proceeds by using bleaching earth clay (BEC) (pH 12.5) in PEG-400 as a green reaction media. All the synthesized compounds were characterized by IR, 1H NMR, 13C NMR and mass spectral data. The pharmacological investigation of the synthesized compounds suggest that most of them showed good antioxidant activity.

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Hooshmand, Seyyed Emad, Bahareh Heidari, Roya Sedghi et Rajender S. Varma. « Recent advances in the Suzuki–Miyaura cross-coupling reaction using efficient catalysts in eco-friendly media ». Green Chemistry 21, n^o 3 (2019) : 381–405. http://dx.doi.org/10.1039/c8gc02860e.

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The ever-increasing interest in the Suzuki–Miyaura cross-coupling reaction (SMR) and its applications, with more than 40 years of history, has increased exponentially in the last decade, which speaks volumes about its efficiency and effectiveness; recent improvements in terms of efficient catalysts in benign media are highlighted.

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Polshettiwar, Vivek, Mallikarjuna N. Nadagouda et Rajender S. Varma. « Microwave-Assisted Chemistry : a Rapid and Sustainable Route to Synthesis of Organics and Nanomaterials ». Australian Journal of Chemistry 62, n^o 1 (2009) : 16. http://dx.doi.org/10.1071/ch08404.

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The use of emerging microwave (MW)-assisted chemistry techniques in conjunction with benign reaction media is dramatically reducing chemical waste and reaction times in several organic syntheses and chemical transformations. The present review summarizes recent developments in MW-assisted synthesis, name reactions and organic transformations, and rapid generation of nanoparticles with uniform size distribution. Greener protocols have been developed for the synthesis of various bio-active heterocycles, namely 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, 1,3-dioxanes, pyrazoles, hydrazones and 3,4-dihydropyrimidin-2(1H)-ones, which proceed under the influence of microwaves and using eco-friendly conditions. These high-yielding methods were catalyzed efficiently by solid-supported Nafion NR50 under solvent-free conditions and polystyrene sulfonic acid in aqueous media. The eco-friendly nucleophilic substitution chemistry in water to generate cyclic amines via double N-alkylation of primary amines or hydrazines by dihalides or tosylates enables the greener synthesis of a range of pharmaceutically active heterocycles. Similarly, efficient MW synthesis of various azides, thiocyanates, and sulfones in aqueous medium occurs wherein nucleophilic substitution reaction takes place in the absence of a phase-transfer catalyst. Bulk and shape-controlled synthesis of noble nanostructures via MW-assisted spontaneous reduction of noble metal salts using α-d-glucose, sucrose, and maltose is described. MW method also accomplishes the cross-linking reaction of poly(vinyl alcohol) with metallic systems such as Pt, Cu, and In; bimetallic systems, namely Pt–In, Ag–Pt, Pt–Fe, Cu–Pd, Pt–Pd, and Pd–Fe; and single-walled nanotubes, multi-walled nanotubes, and buckminsterfullerenes (C-60). The strategy is extended to the formation of biodegradable carboxymethyl cellulose (CMC) composite films with noble nanometals; such metal decoration and alignment of carbon nanotubes in CMC is possible using a MW approach that also enables the shape-controlled bulk synthesis of Ag and Fe nanorods in poly(ethylene glycol).

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Khandebharad, Amol, Swapnil Sarda, Pravin Kulkarni et Brijmohan Agrawal. « Visible Light Assisted Synthesis of 5-Aryl-1,2,4-thiazolidine-3-thiones Under Catalyst-free Condition ». Current Green Chemistry 7, n^o 3 (2 décembre 2020) : 326–33. http://dx.doi.org/10.2174/2213346107999200729131533.

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Abstract: Light energy can be considered as an ideal eco-friendly source of energy for green chemistry. This perspective was used to synthesize 5-aryl-1,2,4-thiazolidine-3-thiones derivative as a quick, efficient and highly improved protocol. The present method developed an energy competent and integrated technique by one-pot condensations of aromatic aldehyde and thiosemicarbazide under the catalyst-free condition in aqueous-alcoholic media. The impact of light on reaction along with mechanical stirring provided a prominent yield of the product. The mild reaction conditions, short reaction time and easy workup procedure, avoidance of heavy metal catalyst and harsh reaction conditions make this protocol greener.

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Kaur, Navjeet. « Ionic Liquid Promoted Eco-friendly and Efficient Synthesis of Six-membered Npolyheterocycles ». Current Organic Synthesis 15, n^o 8 (17 décembre 2018) : 1124–46. http://dx.doi.org/10.2174/1570179415666180903102542.

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Background: The synthesis of N-polyheterocycles by environmentally benign method is highly attractive but challenging proposition. New strategies have been developed for the preparation of polycyclic heterocycles in the last decades. In this review article, the synthesis of nitrogen containing six-membered polycyclic heterocyclic compounds is presented with the application of ionic liquids. This contribution focuses on the literature related to the total synthesis of six-membered N-polyheterocycles. Objective: Ionic liquids not only acted as environmentally benign reaction media but also as catalysts which afforded the very promising replacements of traditional molecular solvents in organic chemistry due to their stability, non-flammability, non-volatility and ease of recyclability. Ionic liquids are utilized in metal catalyzed reactions in place of organic solvents in the last years. It has attracted considerable attention in recent years. Ionic liquids acted as alternatives of organic solvents and these ILs are environment friendly. Conclusion: In the area of green chemistry ionic liquid assisted synthesis is a very promising technique which afforded a flexible platform for the formation of heterocycles. The influence of ILs on the development of efficient and new synthetic protocols over the last decade for the construction of N-polyheterocycles is featured in this review article. These synthetic strategies will continue to attract more attention and will find a wide range of applications in organic synthesis. In conclusion, ionic liquids assisted syntheses have become an efficient and powerful tool in organic chemistry quickly.

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Samani, Amir, Shahrzad Abdolmohammadi et Asieh Otaredi-Kashani. « A Green Synthesis of Xanthenone Derivatives in Aqueous Media Using TiO2-CNTs Nanocomposite as an Eco-Friendly and Re-Usable Catalyst ». Combinatorial Chemistry & ; High Throughput Screening 21, n^o 2 (17 avril 2018) : 111–16. http://dx.doi.org/10.2174/1386207321666180219151705.

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Aim and Objective: The xanthene (dibenzopyran) framework constitutes the core structure of many biologically active compounds, that they have been of interest because of their pharmacological activities like antiviral, antibacterial, anti-inflammatory, and CCR1 antagonist. As heterogeneous catalysts offer several advantages over homogeneous catalysts, the performance of reactions on the surface of nanosized heterogeneous salts has received a great deal of interest in recent years. In the area of nanosized heterogeneous catalysts there is a noticeable range of reactions that are catalyzed efficiently by TiO2 NPs. Moreover, carbon nanotubes (CNTs) as a support can be used to obtain nanoparticles with modified morphology, structural, chemical, electrical, and optical properties. The catalytic activity of titanium dioxide supported on carbon nanotubes has been greatly improved. Materials and Methods: The present methodology focus on the synthesis of 7,7-dimethyl-10-aryl- 6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones, through a condensation reaction of dimedone, aromatic aldehydes and 3,4-methylenedioxyphenol, using a catalytic amount of TiO2- CNTs nanocomposite (15 mol%) at 80 ˚C in aqueous media, within 60-90 min. The TiO2-CNTs nanocomposite was also prepared by a known simple sonochemical method. Results: A series of 7,7-dimethyl-10-aryl-6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones were successfully synthesized in high yields (92-98%). All synthesized compounds were well characterized by their satisfactory elemental analyses, IR, 1H and 13C NMR spectroscopy. The synthesized catalyst was fully characterized by SEM, TEM, XRD, and EDX techniques. Conclusion: In summary, this investigation constitutes a novel and efficient route for the synthesis of 7,7-dimethyl-10-aryl-6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones in high yields, by a three-component reaction of dimedone, aromatic aldehydes and 3,4-methylenedioxyphenol in water and in the presence of the TiO2-CNTs nanocomposite as a green, effective and recyclable catalyst. This novel method has the advantages of high yields, mild reaction conditions, short reaction time, easy work-up, inexpensive reagents and environmentally friendly procedure.

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Iben Ayad, A., C. Belda Marín, E. Colaco, C. Lefevre, C. Méthivier, A. Ould Driss, J. Landoulsi et E. Guénin. « “Water soluble” palladium nanoparticle engineering for C–C coupling, reduction and cyclization catalysis ». Green Chemistry 21, n^o 24 (2019) : 6646–57. http://dx.doi.org/10.1039/c9gc02546d.

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Water stable Pd-NPs prepared in an eco-friendly manner enable highly efficient catalysis of 6 organic reactions in aqueous media with quantities of Pd down to the ppm level and high turnover frequencies.

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Kamakshi, R., et Boreddy S. R. Reddy. « An Efficient, Eco-Friendly, One-Pot Protocol for the Synthesis of 2-Oxazolines Promoted by Ionic Liquid/Indium Chloride ». Australian Journal of Chemistry 59, n^o 7 (2006) : 463. http://dx.doi.org/10.1071/ch06061.

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2-Oxazolines have been synthesized using a solventless ionic liquid melt in good yields at ambient temperatures. The efficiency of various Lewis acid catalysts for the same reaction has been compared. The effectiveness of different alkyl chains in the ionic liquids for the synthesis of oxazolines has been studied and a butylmethylimidazolinium chloride/indium chloride melt has been found to be the best media for promoting the reaction.

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Carvalho, Patrícia M., Rita C. Guedes, Maria R. Bronze, Célia M. C. Faustino et Maria H. L. Ribeiro. « Design of a New Gemini Lipoaminoacid with Immobilized Lipases Based on an Eco-Friendly Biosynthetic Process ». Catalysts 11, n^o 2 (25 janvier 2021) : 164. http://dx.doi.org/10.3390/catal11020164.

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Lipoaminoacids (LAA) are an important group of biosurfactants, formed by a polar hydrophilic part (amino acid) and a hydrophobic tail (lipid). The gemini LAA structures allow the formation of a supramolecular complex with bioactive molecules, like DNA, which provides them with good transfection efficiency. Since lipases are naturally involved in lipid and protein metabolism, they are an alternative to the chemical production of LAA, offering an eco-friendly biosynthetic process option. This work aimed to design the production of novel cystine derived gemini through a bioconversion system using immobilized lipases. Three lipases were used: porcine pancreatic lipase (PPL); lipase from Thermomyces lanuginosus (TLL); and lipase from Rizhomucor miehei (RML). PPL was immobilized in sol-gel lenses. L-cystine dihydrochloride and dodecylamine were used as substrates for the bioreaction. The production of LAA was evaluated by thin layer chromatography (TLC), and colorimetric reaction with eosin. The identification and quantification was carried out by High Performance Liquid Chromatographer-Mass Spectrometry (HPLC-MS/MS). The optimization of media design included co-solvent (methanol, dimethylsulfoxide), biphasic (n-hexane and 2-propanol) or solvent-free media, in order to improve the biocatalytic reaction rates and yields. Moreover, a new medium was tested where dodecylamine was melted and added to the cystine and to the biocatalyst, building a system of mainly undissolved substrates, leading to 5 mg/mL of LAA. Most of the volume turned into foam, which indicated the production of the biosurfactant. For the first time, the gemini derived cystine lipoaminoacid was produced, identified, and quantified in both co-solvent and solvent-free media, with the lipases PPL, RML, and TLL.

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Ojha, Kasinath, Manu Sharma, Hristo Kolev et Ashok K. Ganguli. « Reduced graphene oxide and MoP composite as highly efficient and durable electrocatalyst for hydrogen evolution in both acidic and alkaline media ». Catalysis Science & ; Technology 7, n^o 3 (2017) : 668–76. http://dx.doi.org/10.1039/c6cy02406h.

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Almufarij, Rasmiah S. « Facile Formulation of New Innovative Eco-Friendly Hybrid Protective Coating for Mild Steel in Acidic Media ». Sustainability 15, n^o 3 (3 février 2023) : 2779. http://dx.doi.org/10.3390/su15032779.

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This research deals with the formulation, characterization, and evaluation of new anticorrosive protective coatings. The study objective is to protect mild carbon steel in acidic media by adherent nonporous polymeric coatings formulated from polystyrene and shrimp shells. Solid wastes of shrimp shells are dried into a fine powder and sonicated in toluene. The obtained suspension is refluxed with polystyrene. The hot-melt coatings are applied to the metal surface by the hot dipping technique. The shrimp shells improve the performance of polystyrene. These eco-friendly, low-cost anticorrosive coatings are formulated from solid waste (SW) of shrimp shells and polystyrene (PS) with no aiding additives. Intense vibrational bands in the infrared spectra and the high thermal stability of the coating samples confirm the compatibility of the coating constituents. The results of the evaluation of coating performance by electrochemical impedance spectroscopy and potentiodynamic polarization techniques show that the coating is protective for mild steel in the aggressive acidic media of 1.0 M HCl. The coating protects the metal surface without affecting the corrosion mechanism. Polarization curves show that the coating film retards both the anodic metal dissolution reaction and the cathodic hydrogen evolution reaction, acting as mixed-type inhibitors. The percent protection (%P) increases with the increasing weight percent (wt.%) of PS and the SW of shrimp shells. A %P up to 99% is achieved for the coating composition of 2.0 g/L PS + 0.02 g/L SW. The %P obtained by impedance and polarization measurements are in good agreement. The prepared multi-functional polymeric coating forms an adherent nonporous coating film on the metal surface. Impedance plots show that the coating samples are insulating dielectric coatings that electrically insulate the metal surface from the aggressive acidic media. The coating protects the metal surface by the adsorption mechanism. Shrimp shells fill the pores and increase the stiffness of the polymeric coating film of polystyrene. The obtained results in this study will be useful for all industrial sectors and academic research in the field of corrosion control of metals and alloys.

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Satish Kumar, Nandigama, L. Chandrasekhara Rao, N. Jagadeesh Babu et H. M. Meshram. « A domino green method for the rapid synthesis of novel fused isoquinoline derivatives via Knoevenagel/Michael/cyclization reactions on aqueous media and their photophysical properties ». RSC Advances 5, n^o 116 (2015) : 95539–44. http://dx.doi.org/10.1039/c5ra15948b.

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An expedient, eco-friendly and green-protocol has been developed for the synthesis of novel 4-imino-2-aryl-4H-pyrido[2,1-a]isoquinoline-3-carbonitrile derivatives via Knoevenagel/Michael/cyclisation reactions in one pot under catalyst-free conditions on aqueous media.

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BARROS, SAFIRA M., REBECCA S. ANDRADE, DEISE TORRES, BRUNA G. CHIARI-ANDRÈO, GABRIELA B. R. VELOSO, CRISTINA GONZALEZ et MIGUEL IGLESIAS. « ECO-FRIENDLY TECHNOLOGY FOR REACTIVE DYEING OF CATIONIZED FABRICS : PROTIC IONIC LIQUIDS AS INNOVATIVE MEDIA ». Cellulose Chemistry and Technology 56, n^o 3-4 (5 mai 2022) : 403–25. http://dx.doi.org/10.35812/cellulosechemtechnol.2022.56.36.

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Because of the limitations of traditional dyeing technologies, large amounts of water and chemical additives are used in the dyeing processes, resulting in enormous quantities of polluted wastewater, which has a huge health and environmental potential impact. In the last few years, the interest in researching alternative techniques/materials for the textile industry to reduce the consumption of water used to improve dyeing quality, has considerably increased. Continuing previous research, in this paper, we present a non-aqueous dyeing procedure, testing different types of fabrics with a polyfunctional reactive dye and protic ionic liquids (PILs) as reaction environment, and with cationization pretreatment of the tested fibers. To analyze the effectiveness of the proposed procedure, currently established dyeing quality parameters, such as color absorption and wash fastness of the dyed multifiber fabrics, have been measured and analysed. The obtained dyeing results should be explained by the affinity of cationized multifibers to the reactive dye, as well as by the efficiency of the mechanisms of dye diffusion and chemical bonding on the tested fabrics in protic ionic liquid environment. This new proposed “universal dye” for all kinds of fibers in PIL environment was analyzed under different operational dyeing conditions. The obtained results were satisfying when compared with standard dyeing quality parameters reported in earlier published literature, thus opening opportunities for innovation and optimization.

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Joshi, K. A., J. M. Dhalani, H. B. Bhatt et K. M. Kapadiya. « Synthesis of some new 6-aryl-3-(4-isopropylphenyl)[1,2,4]triazolo[3,4-b][1,3,4] thiadiazoles and its anti-microbial study ». Current Chemistry Letters 10, n^o 4 (2021) : 479–88. http://dx.doi.org/10.5267/j.ccl.2021.4.003.

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New series of fused 1,2,4-triazoles, i.e., 3-(4-isopropylphenyl)-6-substituted phenyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles (5a-5j) have been synthesized via a four-step procedure and using eco-friendly reaction condition at some steps of the synthesis. It was adopted by the formation of hydrazide of methyl 4-isopropylbenzoate (1) followed by reaction with CS2 in basic media to afford potassium salt, which on cyclized to our essential step, 4-amino-5-(4-isopropylphenyl)-4H-1,2,4-triazole-3-thiol (4). The desired adducts (5a-5j) were formed by (4) on reaction with various aromatic acids in POCl3 media. The newly synthesized triazolo- thiadiazoles have been characterized by different spectroscopic techniques and investigated for their in vitro antibacterial and antifungal activity. It was revealed that the compounds 5a, 5c, 5h, and 5i showed interesting antibacterial and antifungal activity compared to the used reference standard.

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Ameta, K. L., Biresh Kumar et Nitu S. Rathore. « Microwave Induced Improved Synthesis of Some Novel Substituted 1, 3-Diarylpropenones and their Antimicrobial Activity ». E-Journal of Chemistry 8, n^o 2 (2011) : 665–70. http://dx.doi.org/10.1155/2011/165047.

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Application of solid support, solvent free reaction condition and a dynamic microwave power system in the chemical synthesis of some novel 1, 3-diaryl-propenones has been described. A series of chalcones(3a-h)were synthesized by the condensation of 4-hydroxy-3,5-dinitroacetophenone with various substituted aromatic aldehydes in presence of montmorrilonite K10 as a catalyst and solid support media under microwave irradiation. The protocol offers several advantages such as simple procedure, fast reaction rate, mild reaction condition, eco-friendly and improved yield as compared to conventional methods. These compounds have been screened for their antibacterial and antifungal activities against different microorganisms. The structures of novel synthesized compounds have been established on the basis of elemental analysis,1H NMR,13C NMR and IR spectral data.

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Thorat, Nitin M., Kiran D. Dhawale, Sandeep B. Kasar, Manali S. Thopate, Limbraj R. Patil et Shankar R. Thopate. « Efficient and Green Synthesis of Bis(indolyl)Methanes using Thiamine Hydrochloride as an Organocatalyst : A Parallel Scrutiny of Microwave Irradiation versus Ultrasonicator Heating in Water ». Current Organic Synthesis 17, n^o 8 (28 octobre 2020) : 679–84. http://dx.doi.org/10.2174/1570179417666200620215101.

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Thiamine hydrochloride is reported to be a highly competent promoter for the synthesis of bis(indolyl)methanes under solvent free conditions using microwave irradiation and ultrasonicator heating in aqueous media. Vitamin B1 is an economical, non-toxic, nonflammable and water soluble green organocatalyst. Moreover, the simple approach, easily operational, short reaction time, high yield and using a little quantity of thiamine hydrochloride makes this method an alternative approach. Present protocol is a simple and eco-friendly approach for the synthesis of bis(indolyl)methanes under microwave and ultrasonicator conditions.

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Qian, Siran, Mingjie Li, Jiaming Liu et Cunde Wang. « A simple green protocol for the synthesis of ethyl 3-amino-1-aryl-1H-benzo[f] chromene-2-carboxylates in aqueous media ». Journal of Chemical Research 41, n^o 8 (août 2017) : 487–90. http://dx.doi.org/10.3184/174751917x15016663252830.

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An eco-friendly and efficient straightforward method has been developed for the synthesis of ethyl 3-amino-1-aryl-1 H-benzo[ f]chromene-2-carboxylate derivatives via 1,4-diazabicyclo[2.2.2]octane (DABCO)-catalysed cyclisation of β-naphthol and 3-aryl-2-cyanoacrylates using water as a green solvent. All products precipitated from the reaction mixture and were isolated by simple filtration. No further work-up nor purification was necessary. The structure of ethyl 3-amino-1-aryl-1 H-benzo[ f]chromene-2-carboxylate was further confirmed by X-ray single crystal analysis.

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Mofidian, Roozbeh, Mojtaba Jahanshahi, Seyed Sharafoddin Hosseini et Mehdi Miansari. « CFD Simulation of Methanol Dehydration Step through an Adiabatic Fixed-bed Reactor of DME Synthesis ». Iraqi Journal of Chemical and Petroleum Engineering 24, n^o 4 (30 décembre 2023) : 31–37. http://dx.doi.org/10.31699/ijcpe.2023.4.3.

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Today, dimethyl ether (DME) is changing to ordinarily worn as a superb aerosol propellant and refrigerant for its eco-friendly characteristics. Lately, with the development of novel chemical energy in the coal industries, it has become a fascinating field of research as an alternative green fuel for diesel machines due to the high cetane number. The DME synthesis processes include catalytic dehydrating methanol in an adiabatic fixed-bed reactor. In this study, to investigate the chemical conditions of the methanol dehydration reaction, CFD simulations of the adiabatic reactor have been assessed. The advantage of the work is a sensitivity analysis was run to find the effect of pressure, kinetics, and velocity on the reactor performance. The results showed that using a γ-Al2O3 catalyst with selective mechanical properties and unique surface properties is a convenient choice for DME synthesis. The CFD simulation results also show that the laboratory data such as pressure, energy, and velocity in the adiabatic reactor meet the reaction requirements well, and deliberated a major vision of what happened in the reactor. Also, the graphs of the temperature profile with changes in physical properties pomp that methanol dehydration reaction strongly depends on environmental factors and gives different results under the influence of other conditions.

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Tang, Cheng, Wenwen Yang, Zhijuan Zou, Fang Liao, Chunmei Zeng et Kunpeng Song. « Facile Synthesis Hyper-Crosslinked PdFe Bimetallic Polymer as Highly Active Catalyst for Ullmann Coupling Reaction of Chlorobenzene ». Polymers 15, n^o 12 (20 juin 2023) : 2748. http://dx.doi.org/10.3390/polym15122748.

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The synthesis of efficient and sustainable heterogeneous Pd-based catalysts has been an active field of research due to their crucial role in carbon–carbon coupling reactions. In this study, we developed a facile and eco-friendly in situ assembly technique to produce a PdFe bimetallic hyper-crosslinked polymer (HCP@Pd/Fe) to use as a highly active and durable catalyst in the Ullmann reaction. The HCP@Pd/Fe catalyst exhibits a hierarchical pore structure, high specific surface area, and uniform distribution of active sites, which promote catalytic activity and stability. Under mild conditions, the HCP@Pd/Fe catalyst is capable of efficiently catalyzing the Ullmann reaction of aryl chlorides in aqueous media. The exceptional catalytic performance of HCP@Pd/Fe is attributed to its robust absorption capability, high dispersion, and strong interaction between Fe and Pd, as confirmed by various material characterizations and control experiments. Furthermore, the coated structure of a hyper-crosslinked polymer enables easy recycling and reuse of the catalyst for at least 10 cycles without any significant loss of activity.

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Du, Jiaqi, Yidan Peng, Xu Guo, Guoliang Zhang, Fengbao Zhang, Xiaobin Fan, Wenchao Peng et Yang Li. « Atomically Dispersed Pd Sites on ZrO2 Hybridized N-Doped Carbon for Efficient Suzuki–Miyaura Reaction ». Catalysts 13, n^o 4 (25 mars 2023) : 651. http://dx.doi.org/10.3390/catal13040651.

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Researchers studying heterogeneous catalysis are intrigued by single-atom catalysts (SACs) due to their ultrahigh atomic utilization. However, only a few reports on SAC-catalyzed classical organic transformations are available. In this work, atomically dispersed Pd sites are confined to a ZrO2 hybridized N-doped carbon skeleton with a smart design. UiO-66-NH2 is used to anchor Pd atoms by the coordination of the donor atoms including lone pairs of electrons and metal atoms. Subsequently, the in situ introduction of ZrO2 doping is achieved using pyrolysis, which helps improve the catalytic performance by modulating the electronic state. The Pd@ZrO2/N–C catalyst obtained from the unique design exhibits a high yield (99%) in eco-friendly media with an extremely low noble metal dosage (0.03 mol% Pd) for the Suzuki reaction. Moreover, Pd@ZrO2/N–C remains highly active after being reused several times and possesses versatility in a variety of substrates. This strategy offers a feasible alternative to designing SACs with atomically dispersed noble metals for heterogeneous reactions.

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Dr. D. Valli Sowbhagyam. « Ionic Liquids as Green Solvents : A Comprehensive Review ». International Research Journal on Advanced Engineering Hub (IRJAEH) 2, n^o 02 (29 février 2024) : 220–24. http://dx.doi.org/10.47392/irjaeh.2024.0035.

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Common reaction media, volatile organic solvents (VOS), contribute significantly to air pollution and pose challenges in separation and recycling processes. As environmental awareness grows, researchers are focusing on developing alternative, eco-friendly solvent systems to replace these traditional VOS. Ionic liquids (ILs) have emerged as promising "green" solvents due to their extremely low vapor pressure and high thermal stability, providing advantages in containment, product recovery, and recyclability. ILs exhibit varying stability to moisture and miscibility with molecular liquids, and their properties like density, melting point, and viscosity can be tailored by selecting appropriate cation and/or anion components. Beyond their role in chemical reactions, ILs find applications in separations, extractions, electroanalytical processes, and chemical sensing. The high ionic character of ILs significantly enhances reaction rates in various chemical processes. These versatile features position ILs as potential alternatives to VOS in a wide range of industrial applications. Moreover, their use as industrial solvents can have economic, social, and ecological impacts by influencing human health and environmental factors. In summary, the exploration of ILs as green solvents represents a crucial step towards addressing environmental concerns associated with traditional volatile organic solvents in industrial chemical processes.

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Liu, Xiong-Li, Xiao-Mei Zhang et Wei-Cheng Yuan. « A simple and eco-friendly method for the aminomethylation of 3-substituted oxindoles via three-component Mannich reaction in aqueous media ». Tetrahedron Letters 52, n^o 8 (février 2011) : 903–6. http://dx.doi.org/10.1016/j.tetlet.2010.12.060.

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Hussien, Fadia Al Haj, Mohammad Keshe, Khaled Alzobar, Joumaa Merza et Ayman Karam. « Synthesis and Nitration of 7-Hydroxy-4-Methyl Coumarin via Pechmann Condensation Using Eco-Friendly Medias ». International Letters of Chemistry, Physics and Astronomy 69 (août 2016) : 66–73. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.69.66.

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A nitro coumarin derivatives has been synthesized via nitration of 7-hydroxy-4-methyl coumarin wich was synthesized via Pechmann condensation resorcinol with a β-ketoester using Amberlyst-15 as a green and efficient catalyst and by caring out the reaction of resorcinol and ethyl acetoacetate (with 1: 1 mol ratio) in the presence of 0.2 g of Amberlyst-15 at 110°C under solvent-free conditions. These nitro coumarin derivatives have biological activity and momentousness in the industrial fields. The purified products were measured the melting points and characterized by spectral methods: FT-IR,1H-NMR ,13C-NMR.

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Hussien, Fadia Al Haj, Mohammad Keshe, Khaled Alzobar, Joumaa Merza et Ayman Karam. « Synthesis and Nitration of 7-Hydroxy-4-Methyl Coumarin via Pechmann Condensation Using Eco-Friendly Medias ». International Letters of Chemistry, Physics and Astronomy 69 (12 août 2016) : 66–73. http://dx.doi.org/10.56431/p-zj1ao8.

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A nitro coumarin derivatives has been synthesized via nitration of 7-hydroxy-4-methyl coumarin wich was synthesized via Pechmann condensation resorcinol with a β-ketoester using Amberlyst-15 as a green and efficient catalyst and by caring out the reaction of resorcinol and ethyl acetoacetate (with 1: 1 mol ratio) in the presence of 0.2 g of Amberlyst-15 at 110°C under solvent-free conditions. These nitro coumarin derivatives have biological activity and momentousness in the industrial fields. The purified products were measured the melting points and characterized by spectral methods: FT-IR, 1H-NMR , 13C-NMR.

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Parga-Marrufo, Cesar, Ivonne L. Alonso-Lemus, Alonso Díaz-Guillen, B. Escobar-Morales et José Escorcia-García. « Electrospun N-S-Codoped Carbon Nanofibers As Metal-Free Electrocatalysts With Catalytic Activity For The Oxygen Reduction Reaction In Alkaline Media ». ECS Transactions 108, n^o 7 (20 mai 2022) : 69–78. http://dx.doi.org/10.1149/10807.0069ecst.

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In this work, we have developed metal-free electrocatalysts based on sulfur and/or nitrogen-doped carbon nanofibers (CNFs) by in situ electrospun doping method. Heteroatom-doped CNFs have diameter ≈ 350 nm and nitrogen and sulfur species on their surface. Moreover, the catalytic activity for the oxygen reduction reaction (ORR) is evaluated in alkaline electrolyte (0.5M KOH). The most active metal-free electrocatalyst labelled as S-CNF has an onset potential of 0.817 V vs. RHE, HO2 - % yield of ≈12-15% and n = 3.7 and high ethanol tolerance. The Accelerated Degradation Test (ADT) show that S-CNF catalytic activity decrease only 13% evaluated at a potential range of 0.6 to 1.0 V vs. RHE. Furthermore, S-CNF even is evaluated by ADT as support (1.0 to 1.6 V/RHE, 6000 cycles) showing high long-term stability decreasing only 11% its catalytic activity. These results indicate N-S-codoped CNFs are a promising and eco-friendly alternative for fuel cells applications.

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Fathollahi, Mostafa, Shahnaz Rostamizadeh et Ali M. Amani. « A Clean, Mild, and Efficient Preparation of Aryl 14H-benzo[a,j]xanthene leuco-dye Derivatives Via Nanocatalytic MCM-41-SO3H Under Ultrasonic Irradiation in Aqueous Media ». Combinatorial Chemistry & ; High Throughput Screening 21, n^o 1 (20 mars 2018) : 5–13. http://dx.doi.org/10.2174/1386207321666180104111508.

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Aim and Objective: The present study has developed an efficient and eco-friendly protocol for the synthesis of aryl-14-H-dibenzo[a,j] xanthenes through a one-pot condensation reaction of 2-naphthol and arylaldehydes in aqueous media using the nanocatalytic MCM-41-SO3H under ultrasonic illumination. Material and Methods: Using SEM and XRD analyses, MCM-41-SO3H nanoparticles were characterized. Therefore, for high magnification, taking the SEM image, the mesoporous surface of MCM-41-SO3H nanoparticles coated with gold for 2 minutes was characterized. Moreover, at a scan rate of 0.02° (2Θ)/sec, XRD analysis from 1.5° (2Θ) to 10.0° (2Θ) was performed. Result: For our considered sample, some well-ordered XRD patterns with one main peak as well as three minor peaks equal to those of MCM-41 materials were observed. Conclusion: The suggested route demonstrates very promising properties like higher yields, decrease in the time of reaction (5-10 min), mild and straightforward conditions, low level of toxicity, and inclusion of a cost-efficient and ecofriendly catalyst having considerable reusability.

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Chaudhary, Ankita, et Jitender M. Khurana. « Advances in the Synthesis of Xanthenes : An Overview ». Current Organic Synthesis 15, n^o 3 (27 avril 2018) : 341–69. http://dx.doi.org/10.2174/1570179414666171011162902.

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Background: Xanthene is pharmacologically important oxygen containing heterocyclic moeity exhibiting an array of potent biological activities like antibacterial, antiviral, antiinflammatory, antitumor, antioxidant, antiplasmodial etc. Other useful applications of these heterocycles are as fluorescent materials for the visualization of biomolecules and in laser technology. Objective: This review gives an insight of the literature available on the methods for the construction of xanthene nucleus. This review article can be reasonably encouraging for those involved in the synthesis of molecules exhibiting a wide range of biological activities involving xanthene as central nucleus and would provide them assistance in developing new eco-friendly, efficient and economical viable methods. Conclusion: Owing to diverse applications of xanthenes, various synthetic methodologies have been developed, whether to construct this privileged scaffold. Many of the reported methods involve the use of various harsh catalysts/reagents that are not environmentally benign, produce a large amount of waste and need longer reaction times. The sustainable and diversity oriented synthesis of xanthene scaffold which incorporates Green Chemistry tools like multicomponent reaction approach, heterogeneous catalysts, alternate reaction media such as water, ionic liquids, polyethylene glycol etc. has also been developed.

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Liu, Xiong-Li, Xiao-Mei Zhang et Wei-Cheng Yuan. « ChemInform Abstract : A Simple and Eco-Friendly Method for the Aminomethylation of 3-Substituted Oxindoles via Three-Component Mannich Reaction in Aqueous Media. » ChemInform 42, n^o 22 (5 mai 2011) : no. http://dx.doi.org/10.1002/chin.201122110.

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Nguyen, Duong Nguyen, Uk Sim et Jung Kyu Kim. « Biopolymer-Inspired N-Doped Nanocarbon Using Carbonized Polydopamine : A High-Performance Electrocatalyst for Hydrogen-Evolution Reaction ». Polymers 12, n^o 4 (15 avril 2020) : 912. http://dx.doi.org/10.3390/polym12040912.

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Hydrogen-evolution reaction (HER) is a promising technology for renewable energy conversion and storage. Electrochemical HER can provide a cost-effective method for the clean production of hydrogen. In this study, a biomimetic eco-friendly approach to fabricate nitrogen-doped carbon nanosheets, exhibiting a high HER performance, and using a carbonized polydopamine (C-PDA), is described. As a biopolymer, polydopamine (PDA) exhibits high biocompatibility and can be easily obtained by an environmentally benign green synthesis with dopamine. Inspired by the polymerization of dopamine, we have devised the facile synthesis of nitrogen-doped nanocarbons using a carbonized polydopamine for the HER in acidic media. The N-doped nanocarbons exhibit excellent performance for H2 generation. The required overpotential at 5 mA/cm2 is 130 mV, and the Tafel slope is 45 mV/decade. Experimental characterizations confirm that the excellent performance of the N-doped nanocarbons can be attributed to the multisite nitrogen doping, while theoretical computations indicate the promotion effect of tertiary/aromatic nitrogen doping in enhancing the spin density of the doped samples and consequently in forming highly electroactive sites for HER applications.

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Feizi Mohazzab, Bahareh, Babak Jaleh, Zahra Issaabadi, Mahmoud Nasrollahzadeh et Rajender S. Varma. « Stainless steel mesh-GO/Pd NPs : catalytic applications of Suzuki–Miyaura and Stille coupling reactions in eco-friendly media ». Green Chemistry 21, n^o 12 (2019) : 3319–27. http://dx.doi.org/10.1039/c9gc00889f.

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The immobilization of palladium nanoparticles (Pd NPs) on stainless-steel mesh entails two steps via deposition of graphene oxide (GO) on the stainless-steel mesh (mesh-GO) by electrophoretic deposition (EPD), and preparation of Pd NPs by laser ablation in liquids (LAL).

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Madhu, Amit, et J. N. Chakraborty. « Recovery and reuse of immobilized α-amylase during desizing of cotton fabric ». Research Journal of Textile and Apparel 22, n^o 3 (10 septembre 2018) : 271–90. http://dx.doi.org/10.1108/rjta-12-2017-0052.

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Purpose Enzymatic desizing using α-amylase is the conventional and eco-friendly method of removing starch based size. Conventionally, enzymes are drained after completion of process; being catalysts, they retain their activity after reaction and need to be reused. Immobilization allows the recovery of enzymes to use them as realistic biocatalyst. This study aims to recover and reuse of α-amylase for desizing of cotton via immobilization. Design/methodology/approach This paper investigates the application of α-amylase immobilized on Chitosan and Eudragit S-100 for cotton fabric desizing. A commercial α-amylase was immobilized on reversibly soluble-insoluble polymers to work out with inherent problems of heterogeneous reaction media. The immobilization process was optimized for maximum conjugate activity, and immobilized amylases were applied for grey cotton fabric desizing. Findings The desizing performance of immobilized amylases was evaluated in terms of starch removal and was compared to free enzyme. The immobilized amylases showed adequate desizing efficiency up to four cycles of use and were recovered easily at the end of each cycle. The amylase immobilized on Eudragit is more efficient for a particular concentration than chitosan. Practical implications Immobilization associates with insolubility and increased size of enzymes which lead to poor interactions and limited diffusion especially in textiles where enzymes have to act on macromolecular substrates (heterogeneous media). The selection of support materials plays a significant role in this constraint. Originality/value The commercial α-amylase was covalently immobilized on smart polymers for cotton fabric desizing. The target was to achieve immobilized amylase with maximum conjugate activity and limited constraints. The reversibly soluble-insoluble polymers support provide easy recovery with efficient desizing results in heterogeneous reaction media.

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Komar, Mario, Tatjana Gazivoda Kraljević, Igor Jerković et Maja Molnar. « Application of Deep Eutectic Solvents in the Synthesis of Substituted 2-Mercaptoquinazolin-4(3H)-Ones : A Comparison of Selected Green Chemistry Methods ». Molecules 27, n^o 2 (16 janvier 2022) : 558. http://dx.doi.org/10.3390/molecules27020558.

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In this study, deep eutectic solvents (DESs) were used as green and eco-friendly media for the synthesis of substituted 2-mercaptoquinazolin-4(3H)-ones from different anthranilic acids and aliphatic or aromatic isothiocyanates. A model reaction on anthranilic acid and phenyl isothiocyanate was performed in 20 choline chloride-based DESs at 80 °C to find the best solvent. Based on the product yield, choline chloride:urea (1:2) DES was found to be the most effective, while DESs acted both as solvents and catalysts. Desired compounds were prepared with moderate to good yields using stirring, microwave-assisted, and ultrasound-assisted synthesis. Significantly, higher yields were obtained with mixing and ultrasonication (16–76%), while microwave-induced synthesis showed lower effectiveness (13–49%). The specific contribution of this research is the use of DESs in combination with the above-mentioned green techniques for the synthesis of a wide range of derivatives. The structures of the synthesized compounds were confirmed by 1H and 13C NMR spectroscopy.

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Alam, Manawwer, Naser M. Alandis, Naushad Ahmad et Mu Naushad. « Synthesis and Characterization of Poly(urethane-ether azomethine) Fatty Amide Based Corrosion Resistant Coatings fromPongamia glabraOil : An Eco-Friendly Approach ». Journal of Chemistry 2016 (2016) : 1–10. http://dx.doi.org/10.1155/2016/5623126.

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A novel attempt has been made to incorporate azomethine group in the backbone of polyurethane etherPongamiaoil fatty amide. The overall reaction was carried out in different steps like preparation of N,N-bis(2-hydroxyethyl)Pongamia glabraoil fatty amide, poly(ether fatty amide), and poly(urethane-ether) fatty amide. The hydroxyl terminated Schiff base, ethane 1,2-di(azomethine) bisphenol, reacts with fatty amide diol and is further treated with toluylene 2,4-diisocynate (TDI) to form poly(urethane-ether azomethine) fatty amide (PUEAF). These synthesized resins were characterized by FT IR,1H NMR, and13C NMR spectroscopic techniques. Molecular weight of PUEAF resin was measured by gel permeation chromatography (GPC), coating was made on mild steel strips, and evaluating their physicochemical and physicomechanical analysis was carried out by standard methods. The PUEAF25 coating showed highest scratch hardness (2.5 kg), gloss (90) at 45°, pencil hardness (4H), and impact resistance (150 lb/inch). Atomic force microscopy (AFM) and differential scanning calorimetry (DSC)/thermogravimetric analysis (TGA) were used to determine the topography and thermal behavior of PUEAF. Corrosion studies of PUEAF coated mild steel were used in different corrosive media (3.5 wt% HCl, 5 wt% NaCl, and tap water) at room temperature using potentiodynamic polarization technique. The results of this study showed that PUEAF coatings exhibit good physicomechanical, anticorrosive properties and get application up to 180°C.

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Xu, Peng, Changli Cen, Nannan Chen, Mengke Zheng, Zhenguo Wu, Nanfang Xu, Jingen Tang et Zhaogang Teng. « Copper Nanoparticles Deposited Cellulose Acetate Microfibers as Heterogenous Catalysts for 4-Nitrophenol Reduction in Aqueous Media ». Nanoscience and Nanotechnology Letters 11, n^o 5 (1 mai 2019) : 630–37. http://dx.doi.org/10.1166/nnl.2019.2936.

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In this work, copper nanoparticles (CuNPs) loaded cellulose acetate microfibers (CAMFs-Cu) are successfully prepared as a novel heterogenous catalyst. For this purpose, the cellulose acetate microfibers (CAMFs) with a diameter of ca. 300–500 nm are fabricated by electrospinning method. Then, CuNPs are deposited onto the CAMFs via a convenient wet reduction process using copper chloride as precursor and sodium borohydride as reduction agent. The chemical composition of the fabricated CAMFs-Cu is characterized by energy dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Scanning electron microscope (SEM) and transmission electron microscopy (TEM) images reveal that the CuNPs with a diameter of approximately 20 nm are homogenously deposited on the CAMFs. The distribution density for the CuNPs increases with precursor concentrations. The catalytic performance shows that the CAMFsCu lead to approximate 100% reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and the reaction constant increases with deposited Cu content. The CAMFs-Cu heterogenous catalysts are very stable and could be reused up to eight times in consecutive runs without any treatment between the cycles. The CAMFs-Cu is thus expected to have great potential as a highly efficient, cost-effective and eco-friendly reusable catalyst for catalytic applications.

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Saha, Moumita, Koyel Pradhan et Asish R. Das. « Facile and eco-friendly synthesis of chromeno[4,3-b]pyrrol-4(1H)-one derivatives applying magnetically recoverable nano crystalline CuFe2O4 involving a domino three-component reaction in aqueous media ». RSC Advances 6, n^o 60 (2016) : 55033–38. http://dx.doi.org/10.1039/c6ra06979g.

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Ahmed, MD Dipu, Kazi Madina Maraz et Ruhul Amin Khan. « Prospects and Challenges of Chrome Tanning : Approach a Greener Technology in Leather Industry ». Scientific Review, n^o 73 (8 juillet 2021) : 42–49. http://dx.doi.org/10.32861/sr.73.42.49.

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The leather industry is one of the heavy-polluting and hazardous industries that is creating toxic and harmful effects on the environment and human health by producing waste chemicals, tannery effluents, and various pollutants. Moreover, Tanning is the required stage to convert raw skin to durable and sustainable skin but most of the chemicals, salts, organic and inorganic toxic pollutants are produced. In commercial practices, Chrome tanning is the highly employed approach that uses a large number of basic chromium salts that becomes the major source of chromium pollutant in the environment. Chromium salt is not only harmful to the environment and ecology but also harms the human body such as causing respiratory problems, infertility and birth defects, skin and lung cancer of the workers. This article has presented two alternatives eco-friendly greener approaches of chrome tanning and waste management technique to reduce the toxic effect on the environment and human health. Firstly, to get rid of these harmful effects, the possible remedy of environmental and human health problems may be considered the vegetable tanning process. Vegetable tanning uses tannins (a class of polyphenol astringent chemicals), which occur naturally in the bark and leaves of many plants. Secondly, chrome tanning associate with ultrasound having a frequency range of 20–100 kHz is commonly employed for enhancing the physical processes and for performing chemical reactions. The basic principle associated with the process is an ultrasonic cavitation in dissolved media. Ultrasound decreases the consumption of conventional water and chemicals because it can also function as a physical activator resulting reduction in environmental pollution which is a prime concern nowadays to approach greener leather technology and eco-friendly leather processing. Furthermore, the possible waste management technique of chrome tanning helps to prevent pollution and ensure eco-friendly green technology of leather processing. Therefore, vegetable tanning and chrome tanning associated with ultrasound having proper waste management will be the viable and sustainable options for the tanners in the forthcoming future.

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Mahamuni, Sandip, Prakash Wadgaonkar et Mansing Anuse. « Rapid liquid-liquid extraction of thallium(III) from succinate media with 2-octylaminopyridine in chloroform as the extractant ». Journal of the Serbian Chemical Society 73, n^o 4 (2008) : 435–51. http://dx.doi.org/10.2298/jsc0804435m.

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A simple solvent extraction study of thallium(III) was conducted. Selective and quantitative extraction of thallium(III) by 2-octylaminopyridine (2-OAP) in chloroform occurred from aqueous sodium succinate medium (0.0075 M) at pH 3.0. Thallium(III) was back extracted with acetate buffer (pH 4.63). The effect of the concentration of succinate and 2-OAP, the role of various diluents, stripping agents, loading capacity of 2-OAP, equilibrium time and aqueous:organic volume ratio on the extraction of thallium(III) was studied. The stoichiometry of the extracted species was determined based on the slope analysis method and found to be 1: 2: 1 (metal:acid:extractant). The temperature dependence of the extraction equilibrium constant was also examined to estimate the apparent thermodynamic functions ?H, ?G and ?S for the extraction reaction. The method is free from interference of a large number of cations and anions. The method was used for the selective extraction of thallium(III) from its binary mixture with Zn(II), Cd(II), Hg(II), Bi(III), Pb(II), Se(IV), Te(IV), Sb(III), Ga(III), In(III), Al(III), Tl(I) and Fe(III). The proposed method was applied to the synthetic mixtures and alloys. It is simple, selective, rapid and eco-friendly.

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Hiremath, Prashant B., et Kantharaju Kamanna. « A Microwave Accelerated Sustainable Approach for the Synthesis of 2-amino-4H-chromenes Catalysed by WEPPA : A Green Strategy ». Current Microwave Chemistry 6, n^o 1 (24 octobre 2019) : 30–43. http://dx.doi.org/10.2174/2213335606666190820091029.

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Background: The agricultural wastes as a source offer an excellent alternative to replace many toxic and environmentally hazardous catalysts, due to their least toxicity, ease of biodegradability, and ability to act as a greener catalytic medium. Some of the agro-waste based catalysts reported are BFE, WERSA, WEB, and WEPBA. 2-Amino-4H-chromene derivatives are promising biologically potent heterocyclic compounds, due to their medicinal applications such as antimicrobial, anti-inflammatory, antibacterial, antiviral, anticancer, antidiuretic, anticoagulant and antianaphylactic activities. The present work describes a microwave accelerated, efficient, eco-friendly and economical approach for the synthesis of 2-amino-4H-chromenes through condensation of substituted arylaldehyde, malononitrile and resorcinol/naphthol catalyzed water extract of pomegranate peel ash (WEPPA) under microwave irradiation. The reaction completed within 3-6 min with good to excellent yield of product isolation. The final product isolated by simple filtration and recrystallization gave a spectroscopically pure form of product and did not require further purification. Methods: The pomegranate peel ash water extract as an agro-waste derived catalyst was employed under microwave irradiation for the economical synthesis of 2-amino-4H-chromene derivatives. Results: The reported agro-waste based catalyst was obtained in the absence of external base, additives and solvent-free synthesis of 2-amino-4H-chromene using aryl aldehyde, malononitrile and resorcinol/ naphthol under microwave irradiation. WEPPA acts as a solvent media and catalyst, as it plays a dual role in the synthesis of 2-amino-4H-chromenes. Conclusion: We established an efficient, simple, agro-waste based catalytic approach for the synthesis of 2-amino-4H-chromene derivatives from the condensation of arylaldehyde, malononitrile and resorcinol/α-naphthol/β-naphthol employing WEPPA as an efficient catalyst under microwave synthesis. The method has found to be a greener, economic and eco-friendly approach for the synthesis of chromene scaffolds. The advantages of the present approach are solvent-free, no external metal, chemical base free, short reaction time and isolated product in good to excellent yields. The catalyst is agro-waste derived, which has abundant natural sources available, thus making the present approach a greener one.

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Articles de revues sur le sujet « ECO- FRIENDLY REACTION MEDIA »

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