Context Of Green Chemistry Research Articles

Insights into the Biological Activities and Substituent Effects of Pyrrole Derivatives: The Chemistry-Biology Connection.

Pyrrole, with its versatile heterocyclic ring structure, serves as a valuable template for generating a diverse range of lead compounds with various pharmacophores. Researchers and scientists globally are intrigued by pyrrole and its analogs for their broad pharmacological potential, prompting thorough investigations aimed at advancing human welfare. This comprehensive review delves into the diverse activities exhibited by pyrrole compounds, encompassing their synthesis, reactions, and pharmacological properties alongside their derivatives. In addition to detailing the characteristics of pyrrole and its derivatives within the context of green chemistry, the review also examines microwave-assisted reactions. It provides insights into their chemical structures, natural occurrences, and potential applications across various domains. Furthermore, the article investigates structural alterations of pyrrole compounds and their implications on their functionality, highlighting their versatility as foundational elements for both functional materials and bioactive compounds. The review emphasizes the need for ongoing research and development in the field of pyrrole compounds to discover new activities and benefits.

AS CHALCONAS NO ENSINO DA QUÍMICA ORGÂNICA EXPERIMENTAL NO CONTEXTO DA QUÍMICA VERDE

CHALCONES IN TEACHING EXPERIMENTAL ORGANIC CHEMISTRY IN THE CONTEXT OF GREEN CHEMISTRY. The article presents the importance of practice in teaching Organic Chemistry in higher education, in addition to doing it following the methods of Green Chemistry, in view of how chemistry is seen as a “villain” due to dangerous reactions and incorrect waste disposal toxic. In this work, three chalcones with different substituents were synthesized: an electron donor (OCH3), an electron withdrawer (NO2) and the unsubstituted one, through 4 different methodologies, the first being the traditional methodology (methodology A) and the following methodologies ecofriendly alternatives. Methods B and C through maceration (without solvent), modifying only the support (BaO and Al2O3, respectively) and finally (methodology D) through microwave irradiation. Method C proved to be as efficient as the traditional one, with the advantage of being carried out without solvent and in a shorter reaction time and could be a replacement for the traditional method.

Gold Complexes with Hydrophilic N-Heterocyclic Carbene Ligands and Their Contribution to Aqueous-Phase Catalysis

N-Heterocyclic carbenes (NHCs) are nowadays one of the most widely employed ligands in organometallic chemistry and homogeneous catalysis due to the inherent stability of the metal-carbene bond and the ease of modification of the backbone as well as the N-wingtips substituents of these ligands. The functionalization of NHCs with hydrophilic groups offers the possibility of using NHC-metal complexes in aqueous catalysis, a hot topic within the Green Chemistry context due to the positive implications associated with the use of water as a reaction medium. In line with the enormous interest aroused by gold complexes in catalysis, significant efforts have been directed in the last years to the design and application of hydrophilic NHC-gold catalysts. This review is aimed to summarize the research in this area. The catalytic applications of water-soluble gold nanoparticles stabilized by hydrophilic NHCs are also covered.

Enhancing the Production of the Phenolic Extracts of Asparagus Using an Advanced Green Process.

Asparagus officinalis L. is a common vegetable widely consumed due to its high consumer acceptance. In addition to its flavor, green asparagus contains a high amount of bioactive compounds with health-promoting effects. In this sense, the growing concern of the public health system to promote a diet with a higher consumption of vegetables makes research on phytochemicals from this food of interest. In order to study the content of bioactive compounds from plant matrices, the combination of advanced extraction and analytical techniques within the context of green chemistry is an indispensable working model in today’s research. In the present experimental work, the composition of the phytochemicals of green asparagus from the Protected Geographical Indication (PGI) located in Huétor Tájar, Granada (Spain), was evaluated by environmentally friendly extraction techniques. In order to carry out this work, the recovery of bioactive compounds was evaluated by pressurized liquid extraction (PLE) using GRAS (Generally Recognized As Safe) solvents (mixtures of water and ethanol). The extraction was optimized using a Response Surface Methodology (RSM) based on a 24 factorial Central Composite Design (CCD). The experimental model was followed by high-performance liquid chromatography coupled to electrospray ionization time-of-flight mass spectrometry (HPLC–ESI-TOF-MS) analytical methodology for a comprehensive characterization. The optimized methodology was compared with conventional solid–liquid extraction protocols using ethanol and water. The results highlighted the potential of advanced PLE techniques compared to conventional systems for the recovery of green asparagus phytochemicals. Moreover, the analytical characterization allowed the identification and quantitation of major phenolic compounds belonging to phenolic acids and flavonoids families. Therefore, an easy, fast, and novel methodology to optimize the extraction of bioactive compounds from green asparagus has been optimized, using Green and GRAS methodology, which enables a better understanding of the bioactive composition of this widely consumed food.

Green Catalysts in the Synthesis of Biopolymers and Biomaterials

AbstractThe modernization processes of the chemical industry over the last few years reinforce concerns about the sustainable use of natural resources and the synthesis of solvent‐free and low toxicity products. Additionally, the development of new catalysts capable of minimizing or even eliminating hazardous substances commonly used in the chemical industry has received increasing attention in the academic and industrial environments within the context of Green Chemistry, based on the search for products and processes capable of reducing or even eliminating the use of hazardous substances. This need becomes even greater when it comes to the synthesis and modification of biopolymers with great applicability in the biomedical field such as poly(lactic acid) (PLA), poly(glycolic acid) (PGA), poly(caprolactone) (PCL) in addition to acrylate‐based polymers. The present review aims to discuss the major classes of green catalysts and biocatalysts, their main characteristics, and different synthetic routes. To emphasize the importance of green catalysts in the biomedical industry, different synthetic routes are discussed to obtain biopolymers and biomaterials whose different degradation products have low or no environmental impact, and whose yield rate, degradability, and selectivity are controlled by presence of a catalyst.

Facile and rapid assembly of high-performance tannic acid thin-film nanofiltration membranes via Fe3+ intermediated regulation and coordination

Non-polyamide (non-PA) thin-film composite nanofiltration (TFC-NF) membranes have received tremendous attention in recent years, but their development is strongly hindered by the complicated fabrication process and the trade-off between permeability and selectivity. Here, we report a highly perm-selective non-PA TFC-NF membrane through 2-minute rapid assembly of tannic acid (TA) on hydrolyzed polyacrylonitrile (PAN) substrate via Fe3+ intermediated regulation and coordination. The optimized membrane with a molecular weight cut off of ~390 Da showed high rejections for salts in a sequence of Na2SO4 (90.2%) > MgSO4 (83.4%) > NaCl (50.0%) > MgCl2 (35.2%) and desirable rejections for organic pollutants (e.g. >99.0% dyes, 92.2% streptomycin and 81.8% chloramphenicol) while maintaining a pure water permeability of as high as 13.6 L·m−2·h−1·bar−1, which clearly outperforms the reported non-PA membranes. In addition, the assembled TFC membrane showed excellent antifouling performance and reasonable structural stability against operation pressure and solution alkalinity. These results are highly promising and indicate a great potential for the membrane to be used in practical nanofiltration application, e.g. water purification and wastewater reclamation. Our work outlines the production of novel high-performance non-PA membrane with a fast fabrication process in a green chemistry context.

An Efficient Mesoporous Cu‐Organic Nanorod for Friedländer Synthesis of Quinoline and Click Reactions

AbstractWithin the green chemistry context, heterogeneous catalysis for the synthesis of N‐heterocycles from renewable resources using non‐precious metals has garnered great interest in terms of economic and environmental perspectives. Herein, we present a triazine functional hierarchical mesoporous organic polymer (HMOP) with nanorod morphology together with large BET surface area ∼1218 m2 g−1, huge pore volume&γτ“;6 mL g−1 and dual micro/mesopore architectures. Subsequent Cu‐coordination with nitrogen atoms of the HMOP provides a robust catalyst (Cu‐HMOP) to accomplish multi‐step cascade reactions for preparation of N‐heterocycles by different routes. For instance, the Cu‐HMOP efficiently catalyzes one‐pot sequential multi‐step oxidative dehydrogenative coupling of 2‐aminobenzyl alcohol with diverse aromatic ketones to afford corresponding quinolines in excellent isolated yields (up to 97 %). Secondly, the present catalyst exhibits good aerobic oxidative dehydrogenation activity of amines to imines. Thirdly, for “click” reaction involving azides‐alkynes, the Cu‐HMOP produced quantitative yield for 1,4‐disubstituted 1,2,3‐triazole derivatives at room temperature using water as solvent. Verification of active metal leaching by a hot filtration test as well as reusability of the retrieved Cu‐HMOP catalysts shows a consistent activity in the multi‐component quinoline synthesis as model reaction.

From Current Science to School – the Facets of Green Chemistry on the Example of Ionic Liquids

Ionic liquids (ILs) are a widely investigated topic in various technical disciplines at the present time. A main focus of the research on ILs lies on applications in the field of a more sustainable, ‘greener’ chemistry that benefits from their unique property combination. This allows for the improvement of existing technologies and the use in novel, innovative processes. Especially the synergistic combination with other concepts of green chemistry is expected to lead to promising application of ILs. Regardless of their presence in current scientific research, they are covered rarely in the didactics of chemistry, although they represent an ideal subject to incorporate fundamental relationships or chemical concepts into teaching. They can also be included in various demonstration or hands-on experiments. Therefore, the topic of ILs is very promising for the transfer of knowledge from chemical research and industry into didactical experiments especially in the greater context of green chemistry. In this contribution, we present some simple experiments that utilize a multifunctional IL as recyclable catalyst in a biphasic homogenous catalysis. The experiments demonstrate the ecological and economic benefits offered by ILs in an intelligent process design compared to the conventional protocols for esterification. It is shown that exploiting the potential offered by the tunability of functional ILs as high-performance chemicals rather than ‘simple solvents’ offers many possibilities for a more sustainable chemical production.

Unexpected Result in the Catalytic Solvent-free Multicomponent Synthesis of 2-Amino-3-cyano-4H-chromene

Multicomponent reactions (MCRs) are efficient and effective methods for the sustainable and diversity-oriented synthesis of heterocycles.1,2 In a green chemistry context, the traditional methods of...

Solvent Welding and Imprinting Cellulose Nanofiber Films Using Ionic Liquids.

Cellulose nanofiber films (CNFF) were treated via a welding process using ionic liquids (ILs). Acid-base-conjugated ILs derived from 1,5-diazabicyclo[4.3.0]non-5-ene [DBN] and 1-ethyl-3-methylimidazolium acetate ([emim][OAc]) were utilized. The removal efficiency of ILs from welded CNFF was assessed using liquid-state nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared spectroscopy (FTIR). The mechanical and physical properties of CNFF indicated surface plasticization of CNFF, which improved transparency. Upon treatment, the average CNFF toughness increased by 27%, and the films reached a Young's modulus of ∼5.8 GPa. These first attempts for IL "welding" show promise to tune the surfaces of biobased films, expanding the scope of properties for the production of new biobased materials in a green chemistry context. The results of this work are highly relevant to the fabrication of CNFFs using ionic liquids and related solvents.

Synthesis of novel benzimidazole-diindolylmethane hybrid compounds within the green chemistry context

Synthesis of novel benzimidazole-diindolylmethane hybrid compounds within the green chemistry context

Zeolites as Green Catalysts for Organic Synthesis: the Cases of H-, Cu- & Sc-Zeolites

Within the Green Chemistry context, one of the major challenges is the replacement of conventional homogeneous catalysts by heterogeneous catalysts, which are easy to handle and usually recyclable since they can be readily recovered. This paradigm change is becoming particularly significant with the development of zeolites, either in their native acidic form or modified by metal ions, as catalysts in organic chemistry. Due to the current burgeoning of this new field, the present review only covers some typical but representative aspects. Typical reactions of carbohydrates and other acid-sensitive organic compounds can be catalyzed by H-zeolites, advantageously replacing dangerous and toxic strong acids. Metal-doped zeolites can act as catalysts for various transformations. Some cycloadditions, including the well-known 'click' reaction, and coupling, specially Cu-catalyzed reactions. This new kind of heterogeneous catalysts can be recycled and reused, in sharp contrast to conventional homogeneous catalysts. Keywords: Zeolites, heterogeneous catalysis, green chemistry, organic synthesis, copper, scandium, solid acids, transition metals.

ChemInform Abstract: When CuAAC ′Click Chemistry′ Goes Heterogeneous

AbstractReview: 281 refs.

When CuAAC 'Click Chemistry' goes heterogeneous

Within the green chemistry context, heterogeneous catalysis is more and more applied to organic synthesis. The well known ‘click chemistry’ and especially its flagship, the copper-catalyzed azide–alkyne cycloaddition reaction (CuAAC), is now catch up by such heterogenisation process and copper ions or metals have been grafted or deposited on or into various solids, such as (bio)polymers, charcoal, silica, zeolites, POM or MOF.

Development and validation of an efficient ultrasound assisted extraction of phenolic compounds from flax (Linum usitatissimum L.) seeds

Flaxseed accumulates in its seedcoat a macromolecular complex composed of lignan (secoisolariciresinol diglucoside, SDG), flavonol (herbacetin diglucoside, HDG) and hydroxycinnamic acids (p-couramic, caffeic and ferulic acid glucosides). Their antioxidant and/or cancer chemopreventive properties support their interest in human health and therefore, the demand for their extraction. In the present study, ultrasound-assisted extraction (UAE) of flaxseed phenolic compounds was investigated. Scanning Electron Microscopy imaging and histochemical analysis revealed the deep alteration of the seedcoat ultrastructure and the release of the mucilage following ultrasound treatment. Therefore, this method was found to be very efficient for the reduction of mucilage entrapment of flaxseed phenolics. The optimal conditions for UAE phenolic compounds extraction from flaxseeds were found to be: water as solvent supplemented with 0.2N of sodium hydroxide for alkaline hydrolysis of the SDG–HMG complex, an extraction time of 60min at a temperature of 25°C and an ultrasound frequency of 30kHz. Under these optimized and validated conditions, highest yields of SDG, HDG and hydroxycinnamic acid glucosides were detected in comparison to other published methods. Therefore, the procedure presented herein is a valuable method for efficient extraction and quantification of the main flaxseed phenolics. Moreover, this UAE is of particular interest within the context of green chemistry in terms of reducing energy consumption and valuation of flaxseed cakes as by-products resulting from the production of flax oil.

Green Synthesis, Molecular Characterization and Associative Behavior of Some Gemini Surfactants without a Spacer Group.

A series of new gemini surfactants without a spacer group, disodium 2,3-dialkyl-1,2,3,4-butanetetracarboxylates, were synthesized in a green chemistry context minimizing the use of organic solvents and applying microwaves (MW) when activation energy was required. Once the desired architecture was confirmed by means of the nuclear magnetic resonance technique (1H-NMR, 1H-1H COSY) for all the studied surfactants, the critical micellization concentration was determined by conductance measurements. The diffusion coefficient of micelles formed by the four compounds was characterized using pulsed field gradient (PFG)-NMR. Diffusion coefficients were found to be dependent on the concentration and on the number of carbon atoms in the alkyl chain. The absence of the spacer group, peculiar to this new series of gemini surfactants, may confer relatively low flexibility to the molecules, with potential implications on the interfacial properties, namely on micellization. These gemini surfactants might have interesting applications in the preparation of composite materials, in nanotechnology, in gene transfection and mainly, due to the low CMCs, as new interesting ingredients of cosmetics and toiletries.

Lactide Polymerisation with Complexes of Neutral N‐Donors – New Strategies for Robust Catalysts

AbstractRing‐opening polymerisation of cyclic esters represents a growing field of research, because the resulting polymers are biodegradable and mostly based on renewable raw materials, which ensures increasing interest in this process within the context of green chemistry. Up to now, neutral N‐donor ligands have been overlooked in their potential to stabilise catalytically active systems. This contribution summarises recent developments in this area as well as their applicability in lactide polymerisation with special regard to the reaction conditions. When a use on the industrial scale is targeted, tolerance towards moisture, air, lactide impurities and high temperatures is an important issue to be considered during catalyst design. A multitude of sodium, calcium and zinc complexes with amines, carbenes, guanidines, phosphinimines, pyridines and tris(pyrazolyl)methanes is discussed and their activity in lactide polymerisation is highlighted.

Coordination chemistry studies and peroxidase activity of a new artificial metalloenzyme built by the “Trojan horse” strategy

In the general context of green chemistry, a considerable research effort is devoted to the elaboration of new artificial metalloproteins that catalyze, under mild conditions, the oxidation of a wide range of organic compounds, using cheap and environmentally friendly oxidants. A new artificial hemoprotein was obtained by the so-called “Trojan horse” strategy involving the non-covalent insertion of a cationic iron–porphyrin–estradiol cofactor into an anti-estradiol antibody. UV–vis titrations showed the formation of a 1/2 antibody/cofactor complex with a dissociation constant K D = 4.10 −7 M. UV–vis determination of the Fe-imidazole binding constants showed that the protein provided a weak steric hindrance around the iron–porphyrin cofactor. The antibody–estradiol–iron–porphyrin complex displayed a peroxidase activity and catalyzed the oxidation of ABTS by H 2O 2 with about double the efficiency of the iron–porphyrin–estradiol alone. Kinetic studies revealed that this was due to a faster formation of the intermediate high valent iron–oxo species in the presence of the antibody protein. Consequently, the association of an anti-estradiol antibody with an iron–porphyrin–estradiol cofactor leads to a new artificial hemoprotein with an interesting peroxidase activity and the “Trojan horse” strategy appears as a valuable method to generate artificial metalloenzymes that could act as biocatalysts for selective oxidations.

Green procedure for the preparation of scented alcohols from carbonyl compounds

Several alcohols--interesting as cosmetic fragrances whose main preparative route on an industrial scale or in the research laboratory is the reduction of the corresponding carbonyl compound--were obtained by a solvent-free methodology in a green chemistry context. The process involves the simple mixing of the carbonyl compound with sodium borohydride dispersed in wet alumina in the solid state; the conversions of the carbonyl compounds were obtained in good yields within short reaction times, without energy consumption. The following carbinols were studied: octan-3-ol, 2-cineolylols (endo-exo mixture), alpha-ionol, 4-methylbenzyl alcohol, 1-phenylethanol, trans-cinnamyl alcohol, p-anisyl alcohol, 4-phenyl-3-buten-2-ol.

The E Factor: fifteen years on

The purpose of this perspective is to review the effect that the E Factor concept has had over the last fifteen years on developments in the (fine) chemical industry and pharmaceutical industry with regard to waste minimisation and to assess its current status in the broader context of green chemistry and sustainability. We conclude that the E Factor concept has played a major role in focusing the attention of the chemical industry world-wide, and particularly the pharmaceutical industry, on the problem of waste generation in chemicals manufacture. It provided, and continues to provide, the impetus for developing cleaner, more sustainable processes.