Eco-friendly Conditions Research Articles

Deuteration of Arylthianthren-5-ium Salts in CD3OD.

Deuteration of arylthianthren-5-ium triflates with CD3OD or CD3OD/CD3COCD3 in the presence of Cs2CO3 by palladium catalysis or photoirradiation allowed the convenient synthesis of deuterated arenes in good yields. The Pd-catalyzed reaction generally gave better yields than the photoinduced deuteration, but exceptions also exist. They could complement each other in some cases. These reactions featured eco-friendly conditions, simplicity, inexpensive deuterium sources, good functional group tolerance, and a range of substrates. Since arylthianthren-5-ium salts could be readily synthesized from arenes and thianthrene 5-oxide, this protocol provided a formal aromatic C-H deuteration with high selectivity, enabling efficient deuterium labeling of multifunctionalized arenes and drug molecules.

Pomegranate Peel Extract-Mediated Green Synthesis of ZnO-NPs: Extract Concentration-Dependent Structure, Optical, and Antibacterial Activity

Plant-based nanoparticles (NPs) have many advantages over physical and chemical methods and featured with several medicinal and biological applications. In this study, zinc oxide NPs (ZnO-NPs) were synthesized using pomegranate peel aqueous extract, under mild and ecofriendly conditions. The ZnO-NPs structure, morphology, and optical properties were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FTIR), and ultraviolet-visible (UV-Vis). Antibacterial activity against Gram-positive and Gram-negative strains were evaluated using the disk diffusion method. The effect of extract concentration (20, 30, and 40 mL) on the final properties of NPs, as well as the NPs concentration used for antibacterial test (50, 100, and 200 mg/mL), were also studied. The results indicate a hexagonal structure with particle size increases as extract concentration increase (D = 18.53, 29.88, and 30.34 nm), while the optical bandgap was decreased (Eg = 2.87, 2.80, and 1.92 eV). The antibacterial activity of ZnO-NPs indicated high efficiency, similar or even higher than that of the control azithromycin, more against S. aureus, increased with NPs concentration, and preferred when NPs prepared from high extract concentration. Such promising physicochemical properties support the usefulness and efficacy of the reported bio-route for production of ZnO-NPs and may encourage its application for large-scale production.

Green synthesis of Cu/Fe3O4 nanoparticles using green tea extract: Evaluation of its catalytic activity, antioxidant and anti-colon cancer effects

• Green synthesis of Cu/Fe 3 O 4 nanoparticles using green tea extract. • Green tea extract was used as a green reducing agent and an excellent stabilizer. • Fe 3 O 4 @ G.tea /Cu nanocomposite have a suitable anticancer activity against colon cell lines. • Fe 3 O 4 @ G.tea /Cu nanocomposite have good antioxidant activity. A sustainable biogenic synthesis for the preparation of green tea plant extract engineered novel magnetic nanocomposite (Fe 3 O 4 @ G.tea ) has been represented in this research. The biocompatible composite was then fabricated with in situ prepared Cu NPs using the green tea derived biomolecules avoiding any harsh chemicals, thus making the procedure absolutely green. The electron rich phytochemicals were additionally used to stabilize the adorned NPs from aggregation or aerial oxidation. Physicochemical features of the ensuing Fe 3 O 4 @ G.tea /Cu nanomaterial was ascertained over a range of instrumental methods, viz., FT-IR, SEM, EDX, elemental mapping, TEM, VSM, XRD, and ICP-AES analysis. Catalytic properties of the bio-nanomaterial were assessed by the synthesis of diverse pyrano[3,2- c ]chromene moieties following a multicomponent reaction (MCR) under eco-friendly conditions. Diverse aromatic and heteroaromatic aldehydes were used in the reaction to afford the products in excellent yields. Reusability of the nanocatalyst was demonstrated by easy magnetic decantation from the reaction medium and subsequent recycling for 8 consecutive runs without considerable loss in its activity. Furthermore, the Fe 3 O 4 @ G.tea /Cu bio-nanomaterial was employed in the biological evaluation against reducing the proliferation of human colorectal cancer and investigating the cytotoxicity against two colorectal cell lines, HT-29 and Caco-2 respectively following MTT assay. The studies documented an increase in % cell viability with increase in material concentration and the corresponding IC 50 values obtained as 384.2 μg/ml and 254.6 μg/ml respectively. Again, anti-oxidant activity of the material was determined by DPPH radical scavenging analysis.

Extraction and Characterization of Cellulose from Agricultural Residues: Wheat Straw and Sugarcane Bagasse

Wheat straw and Sugarcane bagasse are agricultural as well as industrial wastes rich in lignocellulosic components that can be extracted easily and used as a renewable source of energy. The main aim of this present work was to explore the alternative source of cellulose extraction using simple, fast, and eco-friendly conditions. The process involves NaOH degradation, acid hydrolysis, and bleaching using hydrogen peroxide as a bleaching agent. The extracted compound was analyzed by XRD and FTIR techniques. The XRD peaks obtained were specific to cellulose Iβ which is a crystalline allomorph with a monoclinic structure. The crystallite size of cellulose obtained from sugarcane bagasse was 10.51 nm which is larger than the size of cellulose obtained from wheat straw i.e 4.04 nm. Cellulose from sugarcane bagasse showed a crystallinity index of 51.84 % whereas wheat straw showed only 17.94 %. The yield was slightly higher in wheat straw than in sugarcane bagasse. FTIR analysis in sugarcane bagasse showed a characteristic peak at 3255.84 cm-1 which is shifted to 3340 cm-1 in the case of wheat straw. This peak is due to the vibration of the –OH group in both of the materials. However, both of the materials showed the vibration of the C-O-C bond at 1033 cm-1.

Oxidative potential of two Brazilian endophytic fungi from Handroanthus impetiginosus towards progesterone

Biotransformation has been successfully employed to conduct uncommon reactions, which would hardly be carried out by chemical synthesis. A wide diversity of compounds may be metabolized by fungi, leading to chemical derivatives through selective reactions that work under ecofriendly conditions. Endophytic fungi live inside vegetal tissues without causing damage to the host plant, making available unique enzymes for interesting chemical derivatization. Biotransformation of steroids by endophytic fungi may provide new derivatives as these microorganisms came from uncommon and underexplored habitats. In this study, endophytic strains isolated from Handroanthus impetiginosus leaves were assayed for biotransformation of progesterone, and its derivatives were identified through GC-EI-MS analysis. The endophyte Talaromyces sp. H4 was capable of transforming the steroidal nucleus selectively into four products through selective ene-reduction of the C4-C5 double bond and C-17 oxidation. The best conversion rate of progesterone (>90 %) was reached with Penicillium citrinum H7 endophytic strain that transformed the substrate into one derivative. The results highlight endophytic fungi's potential to obtain new and interesting steroidal derivatizations.

Zinc (II) complex immobilized on the surface of magnetic nanoparticles modified with phenanthroline: A novel and efficient nanomagnetic reusable catalyst for cross-coupling reaction of aryl iodides with terminal aromatic alkynes

A novel and green nanomagnetic zinc catalyst were fabricated via the immobilization of zinc (II) complex on the surface of magnetic nanoparticles modified with phenanthroline (MNPs-Phen-Zn(II)). The structure of MNPs-Phen-Zn(II) nanomaterial was characterized by a series of spectroscopic techniques including FT-IR spectroscopy, SEM, TEM, EDX, XRD, VSM, and ICP-OES. The resulting zinc nanomagnetic catalyst was shown high catalytic activity for the synthesis of disubstituted alkynes via C(sp2)–C(sp) cross-coupling reactions of alkynes with aryl iodides under eco-friendly conditions. To the best of our knowledge, it is the first report on the utilization of zinc nanomagnetic catalyst for the Sonogashira type cross-coupling reaction of alkynes with aryl iodides in the absence of added Pd and Cu sources. The simple preparation of the catalyst from commercially available materials, excellent chemoselectivity, easy separation of products, and straightforward recovery and reusability of the catalyst with unaltered activity make our procedure a green and practical method.

ON ONE ASPECT OF SUSTAINABLE MANUFACTURING Power Consumption vs Productivity

The paper presents one aspect of the analysis of energy consumption and productivity of the manufacturing operation. As an example of the operation, the operation of turning with a single-blade tool was taken. Sustainable development in its general concept implies sustainable materials, sustainable design, and sustainable manufacturing. This paper presents an analysis of one important part of sustainable manufacturing, and that is energy saving. The experimental study was conducted as follows. In laboratory conditions, an experimental-mathematical regression model of the relationship between cutting force and processing conditions was defined. Machining experiments were performed under ECO-friendly conditions with technology known as MQCL (Minimum Quantity Cooling Lubrication) machining. The obtained mathematical model was used to calculate the energy consumption and the workpiece material removal rate (MRR, productivity). The results of the analysis showed that there is a lot of space for optimization of machining conditions from the aspect of power consumption, with mandatory calculation and other machining costs, above all, the cost of tools and machine tools. In this regard, recommendations for analysis with the aim of power saving are given.

Wang resin catalyzed sonochemical synthesis of dihydropyrano[2,3-c]pyrazole derivatives and their interactions with SIRT1

The pyrano[2,3-c]pyrazole framework was explored for the design and synthesis of compounds as potential inhibitors of SIRT1. The feasibility of this strategy was reasoned by the unique structural features of this scaffold and the reported cytotoxicity of compounds containing this framework. The sonochemical synthesis of target compounds was accomplished by using the Wang resin (Wang-OSO3H) as a recoverable catalyst under eco-friendly conditions. Thus, the desired 4-substituted 6-amino-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile derivatives were prepared via a 4-component reaction of β-ketoester, hydrazine, aldehyde and malononitrile in pure water in good yields. The recyclability of the catalyst was demonstrated successfully. All the synthesized compounds were initially assessed in silico against the targeted protein i.e. hSIRT1 that indicated compound 5i and 5l along with several other compounds as possible inhibitors. Both of these compounds participated in two vital H-bond interactions with the residue GLN345 and ASN346 in silico that was reflected in their estimated total energy. In vitro assessment of these pyrano[2,3-c]pyrazoles against SIRT1 revealed encouraging inhibitory activities (> 50% inhibition) that was in agreement with the results of docking studies. Indeed, 5i and 5l were identified as the most active compounds in this series. The Structure-Activity-Relationship (SAR) study suggested important role of the C-4 aryl substituent along with the N-1 phenyl ring of the pyrano[2,3-c]pyrazole moiety in the SIRT1 inhibitory activities of this class of compounds. Thus, a OH or Cl group at the p-position of the C-4 benzene ring together with the N-1 phenyl moiety appeared to be beneficial for activity. Overall, the initial design and then sonochemical synthesis followed by in silico as well as in vitro studies allowed identification of pyrano[2,3-c]pyrazole based small molecules as potential inhibitors of SIRT1.

Assisted Synthesis of Coated Iron Oxide Nanoparticles for Magnetic Hyperthermia.

Magnetite nanoparticles were synthesized by the co-precipitation method with and without the assistance of an additive, namely, gelatin, agar-agar or pectin, using eco-friendly conditions and materials embodying a green synthesis process. X-ray diffraction and transmission electron microscopy were used to analyze the structure and morphology of the nanoparticles. Magnetic properties were investigated by SQUID magnetometry and 57Fe Mössbauer spectroscopy. The results show that the presence of the additives implies a higher reproducibility of the morphological magnetic nanoparticle characteristics compared with synthesis without any additive, with small differences associated with different additives. To assess their potential for magnetic hyperthermia, water-based suspensions of these nanoparticles were prepared with and without citric acid. The stable solutions obtained were studied for their structural, magnetic and heating efficiency properties. The results indicate that the best additive for the stabilization of a water-based emulsion and better heating efficiency is pectin or a combination of pectin and agar-agar, attaining an intrinsic loss power of 3.6 nWg−1.

Chromatography free expeditious green synthesis of 3-hydroxy-2-pyrrolidone derivatives under eco-friendly conditions via the oxidation of benzyl amines without catalyst

A sustainable and atom economic one-pot synthesis of biologically significant 3-hydroxy-2-pyrrolidone moieties via the reaction of benzyl amine, aniline (or another benzyl amine) and dialkylacetylenedicarboxylate without catalyst in green solvent has been developed. Some remarkable features of our green procedure are aqueous ethanol solvent, reaction without catalyst, no column chromatography for isolation of the products, higher the value of atom economy (AE) (up to 94.30 %) and lower the E-factor value (up to 0.23 g/g). The reaction principally demonstrates the scope of oxidation of benzyl amines followed by cyclization. This synthetic route is also applicable to gram-scale synthesis.

Green protocols for Tsuji–Trost allylation: an overview

Abstract Since its inception in 1960s, the Tsuji–Trost reaction, an allylic substitution reaction with diverse nucleophiles such as phenols, amines, thiols, and active methylene compounds, has remained as one of the most useful and widely used organic reactions for the construction of C–C and C–heteroatom bonds. Allylic compounds such as allylic acetates, alcohols, halides, and carbonates undergo this transformation which plays an important role in the total synthesis of various natural products. The competence to incorporate synthetically demanding allylic functionalities makes it a beneficial tool for the synthesis of complex molecules. Over the last two decades, major advancements for this unique and facile Tsuji–Trost allylation reaction have been made with special emphasis to develop greener and sustainable protocols. This chapter presents an update on the significant progress focusing on the newly designed catalytic systems with high efficiency, the use of eco-friendly solvents or solvent-free conditions, low or room temperature conditions and waste management, along with future outlook.

Study of optical and morphological properties of nanoparticles semiconductors of zinc oxide synthesized using Mimosa tenuiflora extract for photodegradation of methyl orange

In this work, we report the synthesis of zinc oxide nanoparticles semiconductors using Mimosa tenuiflora extract, as a reducing and stabilizing agent, as well as its photocatalytic activity. The synthesis of ZnO was performed under mild and eco-friendly conditions employing different concentrations 0%, 4%, 6%, and 8% (weight/volume) of extract. The effects of the extract the concentration on the optical, morphological, and structural properties of ZnO nanoparticles were studied by different techniques such as UV–Vis, PL, SEM, FT-IR, and XRD. The results demonstrated the obtaining of agglomerated quasi-spheric nanoparticles, with a crystalline structure similar to wurtzite, and bandgap values dependent on extract concentration. Fourier transform infrared spectroscopy shows the presence of Zn–O vibration band at 447 cm−1. The photocatalytic activity was evaluated by the degradation of methyl orange (MO) dye, as an organic model dye, when is subjected to solar and UV radiation, as well as darkness, where it undergoes degradation around 62%, 100%, and 5%, respectively. The high photocatalytic activity and rate were related to the small particle size, that could provide an efficient interaction between dye and photocatalyst, and at the same time, allow the photon absorption and induce dye photodegradation.

Efficient Synthesis of Dihydropyrimidines Using a Highly Ordered Mesoporous Functionalized Pyridinium Organosilica

A Brönsted acidic ionic solid pyridinium-functionalized organosilica network (PMO-Py-IL) was demonstrated to efficiently catalyse one-pot Biginelli condensation reaction. The green synthesis of 3,4-dihydro-2(H)-pyrimidinones (DHPMs) with high yield was carried out via one-pot three component condensation of β- dicarbonyls, aldehydes, and urea in the presence of a catalytic amount of PMO-Py-IL nanomaterial as an efficient nanocatalyst under solvent free conditions. Furthermore, the catalyst showed outstanding stability and could be easily separated and reused for at least ten reaction runs without significant loss of activity and product selectivity. The green protocol features simple set-up, cost-effectiveness, easy work-up, eco-friendly and mild reaction conditions.

Effective synthesis of cyclic carbonates from CO2 and epoxides catalyzed by acetylcholine bromide-based deep eutectic solvents

Fixing CO2 into cyclic carbonates is urgently required under green and eco-friendly conditions. Herein, we synthesized a series of bio-based deep eutectic solvents (DESs) for catalyzing cycloaddition reaction of CO2 with epoxides. Notably, AcChBr-LMA (2:1) formed by acetylcholine bromide (AcChBr) and L-malic acid (LMA) shows the best catalytic activity (up to 98% yield) and excellent recyclability under mild conditions (0.1 MPa CO2 pressure, 80 °C and 2 h). Mechanism studies have shown that there is a synergistic catalytic effect between the hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD).

Various Techniques for One-Pot Synthesis of 1,3,5-Triazine (s-Triazine) Derivatives: A Review

: Recent studies have shown that one-pot synthesis is a boon for triazines synthesis. One-pot processes had significant success in carrying out complex reactions under mild and eco-friendly conditions. One-pot synthesis is environmentally benign and more economical than other processes in triazines synthesis. The triazine scaffold has provided the starting key point for the design and development of pharmaceutical molecules with wide range of biomedical applications. This review highlights the various methodologies involved for one-pot synthesis of 1,3,5-triazine scaffolds.

Controlled and Predictably Selective Oxidation of Activated and Unactivated C(sp3)-H Bonds Catalyzed by a Molybdenum-Based Metallomicellar Catalyst in Water.

The synthesis of carbonyl derivatives from renewable feedstocks, by direct oxidation/functionalization of activated and unactivated C(sp3)-H bonds under a controlled and predictably selective fashion, especially in late stages, remains a formidable challenge. Herein, for the first time, cost-effective and widely applicable protocols for controlled and predictably selective oxidation of petroleum waste and feedstock ingredients like methyl-/alkylarenes to corresponding value-added carbonyls have been developed, using a surfactant-based oxodiperoxo molybdenum catalyst in water. The methodologies use hydrogen peroxide (H2O2) as an environmentally benign green oxidant, and the reactions preclude the need of any external base, additive, or cocatalyst and can be operated under mild eco-friendly conditions. The developed protocols show a wide substrate scope and eminent functional group tolerance, especially oxidation-liable and reactive boronic acid groups. Upscaled multigram synthesis of complex steroid molecules by late-stage oxidation proves the robustness and practical utility of the current protocol since it employs an inexpensive recyclable catalyst and an easily available oxidant. A plausible mechanism has been proposed with the help of few controlled experiments and kinetic and computational studies.

Synergistic effect of GO/SrFe12O19 as magnetic hybrid nanocatalyst for regioselective ring-opening of epoxides with amines under eco-friendly conditions.

Herein, a highly efficient magnetically separable hybrid GO/SrFe12O19 nanocomposite was synthesized via dispersing M-type strontium hexaferrite (SrFe12O19) on graphene oxide (GO) sheets. First, SrFe12O19 nanoparticles (NPs) and GO sheets were prepared via chemical coprecipitation and chemical oxidation of graphite powder, respectively. Chemically reduced GO (rGO) and rGO/SrFe12O19 were also prepared for comparison purposes. Thereafter, the prepared nanostructured materials were explored by XRD, FTIR, FESEM-EDX, BET, and Zetasizer analyses. All the characterizations confirm the nanoscale and the high stability structures of the prepared materials. The prepared hybrid magnetic nanocomposite GO/SrFe12O19 exhibited a high surface area value resulting in a high catalytic activity and selectivity for the epoxide ring-opening with amines in neat water. The use of hybrid GO/SrFe12O19 compared with pure SrFe12O19 and GO sheets is of great interest for using environmentally benign heterogeneous nanocatalysts, for the synthesis of β-amino alcohols, with excellent recyclability under eco-friendly conditions. Moreover, a mechanistic study was performed through density functional theory (DFT) calculations and Parr functions to explain the observed reactivity and selectivity of SrFe-GO catalyst in the epoxide ring-opening reactions.

Brønsted acid-catalyzed cascade cyclization: an efficient strategy for divergent synthesis of cyclohepta[b]indole derivatives

An efficient acid-catalyzed three-component cascade strategy by employing 3,3′-bis(indolyl)methanes (BIMs) as masked 1,4-nucleophiles was established for synthesizing cyclohepta[b]indoles under mild and eco-friendly conditions.

Nitrogen-doped lignin-derived carbon for catalytic reduction of hexavalent chromium via HCOOH-mediated hydrogenation.

It is highly desirable to explore efficient catalysts for reducing toxic Cr6+ to benign Cr3+ under mild and eco-friendly conditions. This article describes a facile fabrication of nitrogen doped carbon (N@C-g-C3N4) as a metal-free catalyst for Cr6+ reduction using lignin as a carbon source and g-C3N4 nanosheets as a nitrogen source. The structural properties of the N@C-g-C3N4 catalyst are characterized by TEM, HR-TEM, XRD, TGA, Raman, EDS-mapping, XPS and BET techniques. The summation of these analyses sheds light on the high surface area (903 m2 g−1), mesopore size (17.3 nm) and defects (ID/IG = 0.97) of N@C-g-C3N4, which contribute to its excellent catalytic activity in HCOOH-mediated reduction of Cr6+ to Cr3+ with high rate constant (2.98 min−1) and turnover frequency (2.21 molK2Cr2O7 gcatalyst−1 min−1) and complete degradation (100%) within 5 min. The catalytic performance of the catalyst reveals that the reduction activity is significantly dependent on the concentration of Cr6+ and HCOOH, catalyst loading, pH, temperature, and foreign ions. Particularly, the N@C-g-C3N4 catalyst shows superior stability and renewability with little loss of activity (≥95%) after 8 months storage and five repeated uses. Furthermore, N@C-g-C3N4 can be applied in other hydrogenation reactions involving K3[Fe(CN)6], 4-NP and BPA using NaBH4 as a hydrogen donor, and the removal of organic dyes. These findings illustrate that N@C-g-C3N4 as a metal-free catalyst is effective, versatile and eco-friendly for the reduction of Cr6+ from contaminated environments.

Black yet green: A heterogenous carbon-based acid catalyst for the synthesis of biscyclic derivatives under eco-friendly conditions

Black yet green: A heterogenous carbon-based acid catalyst for the synthesis of biscyclic derivatives under eco-friendly conditions