Green Conditions Research Articles

Efficient triethylamine sensing achieved by in-situ Zn2+ doping regulated Mo-MOFs derived MoO3/ZnMoO4 heterostructures

Triethylamine (TEA) poses severe safety hazards to industrial production and human health. To accurately detect TEA concentrations and rapidly warn of leakage, a simple reflux condensation method was deployed to successfully incorporate Zn2+ in situ into Mo-MOFs precursor in a green, safe, and time-efficient synthesis condition. Subsequently, through calcination, MoO3/ZnMoO4-X (MMZ-X) were prepared, which exhibited an increased number of defects and enriched porosity, facilitating the access and interaction of TEA with adsorption sites. Simultaneously, rationally built in situ MoO3/ZnMoO4 heterostructures accelerated carrier migration and induced a drastic resistive change. MMZ-2 demonstrated outstanding TEA sensing performance, exhibiting extremely high sensitivity (R = 572.3, 100 ppm), along with superior selectivity, repeatability and stability, rapid response and recovery times, and a low detection limit. Moreover, the key intrinsic parameters of the heterostructure on the atomic scale were determined by density functional theory (DFT) calculations, providing a detailed elucidation of the sensing enhancement mechanism of the MoO3/ZnMoO4 heterostructure. The simple and efficient synthesis method and the related mechanistic analysis pave a new path for designing high-performance TEA gas sensors with practical applications.

Moisture sorption and its induced deformation of juvenile wood at different radial positions in poplar wood at the tissue scale

Juvenile wood exhibits significant variations in its properties across the radial direction, which responds strongly to water and can impact its applications in various scenarios. Wetwood, a specific presence in juvenile wood, is more prevalent in certain species. In this study, we focused on poplar (Populus x euramericana cv. 'San Martino') and analyzed the moisture content (M) and hygroscopic deformation of juvenile wood near the pith (wetwood) and in juvenile wood near the bark (normal wood) in real-time at the tissue scale (earlywood and latewood). To achieve this, we employed a dynamic vapor sorption analyzer in combination with a Dino-Lite Edge digital microscope. By utilizing the Guggenheim-Andersen-de Boer (GAB) model and the Kelvin equation, we examined the relationship between the bound water and hygroscopic deformation. The results revealed that the M in green condition of wetwood was significantly higher than that of normal wood. However, the disparity in moisture sorption capacity between wetwood and normal wood below the fiber saturation point contributed only minimally to this phenomenon. Regarding for hygroscopic deformation, it was observed that not all wetwood samples exhibited a greater shrinkage/swelling compared to normal wood samples. This variation can be attributed to structural factors, such as differences in microfibril angle, crystallinity, and cell wall ratios. Furthermore, it was found that the swelling ratio caused by 1 % of bound water (SwR-B) increased with rising relative humidity (RH) within the range of 0–90 % RH. However, the SwR-B stabilized or slightly decreased in the range of 90 %-95 % RH. This behavior is believed to be linked to the formation of capillary condensed water at higher humidity levels. Additionally, we found that the swelling ratio resulting from 1 % of polylayer water exceeded that caused by 1 % of monolayer water.

Developing an integrated solid desiccant dehumidifier and dew-point evaporative cooler for green air conditioning

The advancement of eco-friendly air conditioning technology has garnered significant interest in light of energy shortages and concerns regarding global warming. However, current research endeavors have encountered obstacles in addressing issues like chemical erosion and energy-intensive processes. A promising solution to overcome these challenges involves integrating a solid desiccant coated heat exchanger-dehumidifier (SDHED) with a dew-point evaporative cooler (DPEC). This innovative approach eliminates the need for condensation dehumidification, reduces compressor workload, and eliminates the use of harmful refrigerants. This study marks a pioneering effort in experimentally assessing and analyzing the performance of an integrated SDHED and DPEC system. Parametric studies have been carried out under various ambient and application conditions, yielding impressive experimental results. The DPEC achieves a dew-point effectiveness of 0.9, a DPEC COP of 15.9, and an electric COP of the integrated system reaching an impressive 6.43. The dynamic characteristics of the integrated system have been scrutinized, unveiling the underlying mechanisms of its operation. Additionally, this study outlines development methodologies for the integrated green air conditioning system, encompassing material selection and prototype testing. The findings underscore the potential of the integrated SDHED and DPEC system to enhance indoor comfort and reduce energy consumption concurrently, making it a compelling choice for future environmentally responsible building designs.

Organocatalytic Synthesis of (Hetero)arylidene Malononitriles Using a More Sustainable, Greener, and Scalable Strategy.

The establishment of a green and sustainable Knoevenagel condensation reaction in organic chemistry is still crucial. This work aimed to provide a newly developed metal-free and halogen-free catalytic methodology for the synthesis of CS and (hetero-) arylidene malononitriles in the laboratory and industrial scale. The Knoevenagel condensation reaction of various carbonyl groups with malononitrile was investigated in ethanol, an ecofriendly medium, in the presence of seven nitrogen-based organocatalysts. A comparative study was conducted using two as-obtained and four commercially available nitrogen-based organocatalysts in Knoevenagel condensation reactions. The synthesis of CS gas (2-chlorobenzylidene malononitrile) using a closed catalytic system was optimized based on their efficiency and greener approach. The conversion of 100% and excellent yields were obtained in a short time. The products could be crystallized directly from the reaction mixture. After separating pure products, the residue solution was employed directly in the next run without any concentration, activation, purification, or separation. Furthermore, the synthesis of 2-chlorobenzylidenemahmonitrile (CS) was carried out on a large scale using imidazole as a selected nitrogen-based catalyst, afforded crystalline products with 95 ± 2% yield in five consecutive runs. Energy efficiency, cost saving, greener conditions, using only 5 mol% of organocatalyst, high recyclability of catalyst, prevention of waste, recycling extractant by a rotary evaporator for non-crystallized products, demonstrated the potential commercial production of CS using imidazole in ethanol as an efficient and highly recyclable catalytic system.

Partial Photoelectrocatalytic Oxidation of 3‐Methylpiridine in Green Conditions by Nanotube/Nanowire Ti/TiO2 Plates Prepared in Aqueous, Glycerol, or Ethylene Glycol Medium

AbstractNanotube/nanowire structured TiO2 samples on Ti plates were prepared by anodic oxidation in aqueous, glycerol or ethylene glycol medium under different experimental conditions and characterized by XRD, SEM‐EDX, electrochemical methods (photocurrent profiles and electrochemical impedance spectroscopy). The nanostructured TiO2 was built on relatively large Ti plates, and consequently, in some preparation conditions, different morphologic properties were observed in the underside and upside zones of the electrodes, especially in ethylene glycol medium. The electrodes were tested for selective photoelectrocatalytic oxidation of 3‐methylpyridine to 3‐pyridinemethanol, 3‐pyridinemethanal and vitamin B3 in water under UVA irradiation. The best performance was found with the electrode prepared in ethylene glycol/water/NH4F (98/2/0.3 w/w) medium at 36 V potential for 3 h, while the worst was that prepared in aqueous medium which showed the shortest nanostructure length. Unlike photoelectrocatalysis and photocatalysis, no aromatic alcohol/carbonyl products were obtained in electrocatalytic and photolytic experiments. The selectivity values of the products were similar for the various electrodes, while the morphology of the nanotubes/nanowires and their quantity which affects the total active surface area were essential for the substrate conversion. The results also show that the photocurrent intensity, XRD peak intensity, and electrical conductivity are correlated with photoelectrocatalytic activity of the Ti/TiO2 electrodes.

Biocatalyst mediated green approach for 1,8-dioxo-octahydroxanthenes: SCXRD, Hirshfeld analysis and DFT studies as inhibitors of HIV reverse transcriptase

AIDS, caused by human immunodeficiency virus (HIV) is persistent on being one among the deadliest disease of all time. It destroys the immune system of the body and there is currently no effective cure for this. In this regard, in continuation to our studies on green catalysts, more efficient, constructive, and environmentally sustainable protocols for the synthesis of xanthene and its derivatives as HIV Reverse Transcriptase inhibitors were developed with the use of biocatalyst via baker's yeast that explores a viable approach on expanding environmental challenges and enlightens the superiority and exclusivity of this protocol. The current approach manifests numerous notable advantages that include ease of preparation, handling and benignity of the catalyst, low cost, green reaction conditions, facile workup, excellent yields (87–96 %) with extreme purity. The title compounds were docked on the crystal structure of a catalytic complex of HIV-1 reverse transcriptase (PDB: 1RTD). The C-score values achieved in the range 6.68–3.05 suggest that docking analysis was propitious signifying the review of all the forces of interaction between the ligand and the protein. The crystal studies and DFT analysis of compound 3d correlate the optimized geometrical features with empirically accessible XRD data.

Effects of different light qualities on embryonic development of Sepia pharaonis

To investigate the impact of different light qualities (red, blue, green, yellow, and white light) on the embryonic development of Sepia pharaonis, this experiment studied the effects of different light qualities on the timing of embryonic development, incubation period, hatching rate, malformation rate, weight of hatchlings, and survival rate on the 7th day after hatching. The findings demonstrated a significant influence of different light qualities on the embryonic development of S. pharaonis (P<0.05). Specifically, red and blue light led to increased occurrences of phenomena such as yolk surface cracking, cell autolysis, coagulation of cells in the animal pole, yolk sac edema, malformations in endoskeleton development, and decreased pigmentation and whitening of the body surface compared to the control group (white light). Conversely, green light showed a tendency to reduce these phenomena. The hatching rate and hatching cuttlefish weight were highest under green and yellow light conditions, with significantly greater survival rate on the 7th day after hatching compared to red, blue, and white light conditions. Furthermore, the malformation rate was notably lower under green light conditions compared to other light groups. Red and blue light conditions exhibited the shortest hatching periods, significantly outpacing other light groups. In conclusion, green light appears advantageous for enhancing hatching rate, the quality and health of hatched larvae, reducing malformation occurrences and embryonic mortality, and improving overall hatching quality.

Light-driven acetic acid coupling for the production of succinic acid

Treating and recycling high concentration acetic acid in the exhaust water has long posed a challenge in industry. These wastes containing acetic acid are typically processed via basic neutralization, characterized by high acidity and resistance to degradation, which can bring potential economic burden and environmental hazards. Here we report a new photocatalytic conversion route for addressing high concentrations of acetic acid. This process transforms acetic acid into valuable succinic acid through dehydrogenative coupling. Additionally, the photocatalytic conversion of acetic acid exhibits structure sensitivity when employing Pt cocatalysts of varying sizes. Through inhibiting the undesirable H termination of active free radicals over small Pt atoms and clusters, the rate of undesired decarboxylation reactions can be decreased by 75 %. This effectively enhances the selectivity of the coupling product succinic acid by 2.1 times, achieving a succinic acid formation rate of 7.28 mmol/(gcat•h). This work offers a theoretical guidance for searching value-added reaction pathways of acetic acid, thereby establishing an innovative approach for high concentration exhaust acetic acid treatment and converting low value monocarboxylic molecules into valuable diacid polymerization monomers under a mild and green condition.

A green Heck reaction protocol towards trisubstituted alkenes, versatile pharmaceutical intermediates.

The Heck reaction is widely employed to build a variety of biologically relevant scaffolds and has been successfully implemented in the production of active pharmaceutical ingredients (APIs). Typically, the reaction with terminal alkenes gives high yields and stereoselectivity toward the trans-substituted alkenes product, and many green variants of the original protocol have been developed for such substrates. However, these methodologies may not be applied with the same efficiency to reactions with challenging substrates, such as internal olefins, providing trisubstituted alkenes. In the present work, we have implemented a Heck reaction protocol under green conditions to access trisubstituted alkenes as final products or key intermediates of pharmaceutical interest. A set of preliminary experiments performed on a model reaction led to selecting a simple and green setup based on a design of experiments (DoE) study. In such a way, the best experimental conditions (catalyst loading, equivalents of alkene, base and tetraalkylammonium salt, composition, and amount of solvent) have been identified. Then, a second set of experiments were performed, bringing the reaction to completion and considering additional factors. The protocol thus defined involves using EtOH as the solvent, microwave (mw) irradiation to achieve short reaction times, and the supported catalyst Pd EnCat®40, which affords an easier recovery and reuse. These conditions were tested on different aryl bromides and internal olefines to evaluate the substrate scope. Furthermore, with the aim to limit as much as possible the production of waste, a simple isomerization procedure was developed to convert the isomeric byproducts into the desired conjugated E alkene, which is also the thermodynamically favoured product. The approach herein disclosed represents a green, efficient, and easy-to-use handle towards different trisubstituted alkenes via the Heck reaction.

Hypervalent Iodine Promoted Selective [2 + 2 + 1] Cycloaddition of Aromatic Ketones and Methylamines: A One-Pot Access to 1-Pyrrolines.

Herein, a versatile highly regioselective three-component annulation of simple aromatic ketones and methylamines using a hypervalent iodine reagent for polyarylated 1-pyrrolines has been described in good to excellent yields. Meanwhile, unsymmetrical 1-pyrroline isomers could be realized and synthesized. Such an intriguing one-pot two-step tandem assembly strategy with green conditions and high regioselectivity shows predictable inspiration in related annulation reactions.

Dewatering behavior of wet oil palm sawn timber during flat compression

ABSTRACT One obstacle to the industrial processing of oil palm wood is its nearly water-saturated state in green condition and its high tendency to develop cell collapse during kiln drying. This study analyzed mechanical dewatering by flat compression as an alternative pre-drying method for wet oil palm sawn timber. In the process, boards 700 mm long were compressed at ratios of 40% and 60% using a laboratory press, which resulted in water extraction of the free water varying between 38–52% and 60–73%, respectively. Since unperforated press plates were used, the water could only escape over the crosscut and long edges. The extent to which the crosscut and long edges were involved in dewatering was examined, and found to depend on the position of the board in the trunk due to the different water permeability conditions at the different heights. Permeability measurements, therefore, were carried out on cylindrical specimens using a specifically designed testing device. For the analysis of the hydrostatic pressure development in the boards, three pressure transducers were installed at different distances to the crosscut at half board thickness. The analysis of the recovery of compression showed, that the boards recovered to a large extend immediately after compression.

Designed to Degrade: Tailoring Polyesters for Circularity.

A powerful toolbox is needed to turn the linear plastic economy into circular. Development of materials designed for mechanical recycling, chemical recycling, and/or biodegradation in targeted end-of-life environment are all necessary puzzle pieces in this process. Polyesters, with reversible ester bonds, are already forerunners in plastic circularity: poly(ethylene terephthalate) (PET) is the most recycled plastic material suitable for mechanical and chemical recycling, while common aliphatic polyesters are biodegradable under favorable conditions, such as industrial compost. However, this circular design needs to be further tailored for different end-of-life options to enable chemical recycling under greener conditions and/or rapid enough biodegradation even under less favorable environmental conditions. Here, we discuss molecular design of the polyester chain targeting enhancement of circularity by incorporation of more easily hydrolyzable ester bonds, additional dynamic bonds, or degradation catalyzing functional groups as part of the polyester chain. The utilization of polyester circularity to design replacement materials for current volume plastics is also reviewed as well as embedment of green catalysts, such as enzymes in biodegradable polyester matrices to facilitate the degradation process.

The new phthalic acid-based deep eutectic solvent as a versatile catalyst for the synthesis of pyrimido[4,5-d]pyrimidines and pyrano[3,2-c]chromenes

A new DES (MTPPBr-PHTH-DES) was prepared from a mixture of methyltriphenyl-phosphonium bromide (MTPPBr) and phthalic acid (PHTH). The eutectic point phase diagram showed that a one-to-one molar ratio of MTPPBr to PHTH is the optimal molar ratio for the synthesis of new DES. Then, it was characterized with various techniques such as FT-IR, TGA/DTA, densitometer, eutectic point, and NMR and used as a novel acid catalyst in the synthesis of pyrimido[4,5-d]pyrimidines and pyrano[3,2-c]chromes in solvent-free condition. Short reaction time, low temperature, high efficiency, green condition, and easy recycling and separation of the DES catalyst are among the most important features of the presented method.

Iron-Mediated Bromocyclization of Olefinic Amides for the Synthesis of Bromobenzoxazines

AbstractAn iron-mediated bromination/cyclization for the synthesis of bromobenzoxazines from olefinic amides has been successfully developed. In this protocol, the simple iron salt FeBr3 was employed as a bromination reagent, giving the bromobenzoxazine products in moderate to excellent yields. This methodology features good functional group tolerance, gram-scale synthesis, and green reaction conditions by the use of air as the terminal oxidant. Preliminary mechanistic studies suggest that a free radical pathway is involved.

An Efficient and Magnetically Retrievable Mixed Metal Oxide Nanocatalyst for the Aqueous Media Three-Component Synthesis of Naphtho [1,2-e] [1,3] Oxazine Derivatives Under Green Conditions

Background: In recent years, the use of nanomaterials as heterogeneous catalysts has attracted much attention in organic reactions. Methods: A magnetically separable mixed metal oxide, Manganese Zinc Iron Oxide (Mn2O3/Fe3O4/ZnO) nanoparticles as nanocatalyst (Mmo@NCt) were synthesized using ultrasonic wave methods in the presence of polyethylene glycol as surfactant. In the second part of the present study, a practical procedure for the one-pot ternary condensation of aromatic aldehydes, β- naphthol, and urea in short reaction time for the synthesis of pharmaceutically interesting naphtho[ 1,2-e][1,3]oxazine derivatives using Mmo@NCt as an efficient, cost-effective and recyclable nanocatalyst under green conditions has been developed. Results: The analysis of phase purity, magnetic structure, size, and morphology of the as-synthesized nanocatalyst was characterized by X-ray diffraction, VSM, SEM, and EDX techniques. The results of SEM imaging showed that all compounds have a spherical morphological structure with a mean diameter of 16.50 ± 3.94 nm. The structure of the products was confirmed by FT-IR, 1HNMR spectroscopy, and melting point. Conclusion: This project was designed and performed with the use of magnetic nanocatalysts as a suitable method with high efficiency a shorter time for the synthesis of naphthoxazinones heterocyclic compounds due to the medicinal importance of water as a green solvent.

Insights into microwave‐promoted synthesis of 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives catalyzed using new Pd (II),Cu (II),VO (II), and Ag(I) complexes as a heterogeneous catalyst and computational studies

Four novel Pd (II), Cu (II), VO (II), and Ag(I) complexes were prepared from benzimidazole ligand through bidentate chelating mode. Alternative spectral and analytical tools were applied to elucidate their structural and molecular formulae. This study was extended to investigate stability and stoichiometry of complexes in solution, using standard methods. In addition, the best atomic distribution within structural forms was obtained via the density functional theory (DFT) method. This computational study fed us with significant physical characteristics for differentiation. Also, DFT/time‐dependent DFT computations were performed applying (B3LYP/6‐311++G[d,p]/aug‐cc‐pVTZ/aug‐cc‐pVTZ‐PP) level in order to investigate the electronic behavior of the compounds. These results demonstrated good agreement with the experimental data. Computational data discriminate Pd (II) complex by some physical features, which may be promising in the catalytic field. This complex was selected to play a catalytic function to synthesize 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives using microwave irradiation in a one‐pot reaction. The catalyst was selected for this application based on the history of Pd (II) complexes and the properties expected theoretically. A condensation reaction for 3‐methyl‐5‐pyrazolone, aromatic aldehyde, and 5‐aminotetrazole was carried out under mild reaction conditions by microwave irradiation. All reaction conditions were optimized among those variable Lewis acid catalysts in comparison with our new complexes. DOBPAPd catalyst displayed superiority in overall trials with high yield, short time, and green conditions (solvent H2O/EtOH). Also, the recovery of hetero catalyst was succeeded and reused by the same efficiency up to five times after that the efficiency was reduced. The mechanism of action was proposed based on the ability of Pd (II) for adding extra‐bonds over z‐axis and supported by theoretical aspects.

MIL-88-NH2(Fe) conjugated pectin through a post-modification Ugi four-component reaction: A robust bio-based catalyst for the synthesis of cyclic carbonate via CO2 fixation reaction

The functionalization of materials via multicomponent reactions (MCRs) led to a recent surge in the interest of researchers, owing to the creation of exceptional properties in materials. Herein, a novel robust porous catalyst was prepared via the conjugation of MIL-88-NH2(Fe) and pectin (DAP/MIL-88-NH2(Fe)) through the post-modification Ugi four-component reaction (Ugi-4CR) for the first time. To achieve this aim, pectin was oxidized using sodium periodate as an oxidant agent to produce dialdehyde pectin (DAP). Next, the generated carbonyl functional groups participated in the Ugi-4CR of MIL-88-NH2(Fe), 4-methyl carboxylic acid, and cyclohexyl (c-hex) isocyanide to produce DAP/MIL-88-NH2(Fe) catalyst. The catalytic activity of the prepared bio-based catalyst was examined in producing cyclic carbonates through the chemical fixation of CO2 with epoxides in the presence of TBAB as a co-catalyst. Interestingly, catalytic experiments revealed that the prepared bio-based catalyst could be remarkably active regarding the CO2 fixation reaction and performed it in the shortest reaction time (1 h) via high CO2 adsorbent capacity. The outstanding benefits of the prepared bio-based catalyst include its non-hazardous nature, inexpensive, green and gentle reaction conditions, and ability to be reusable in several runs with slight loss of catalytic activity due to a more durable framework with high chemical and thermal stability.

Efficient Photocatalytic Partial Oxidation of Aromatic Alcohols by Using ZnIn2S4 under Green Conditions.

The ternary chalcogenide ZnIn2S4 (ZIS) has been synthesized by a simple hydrothermal method in which the carcinogen thiacetamide, universally used as a precursor, has been, for the first time, replaced successfully with the harmless thiourea. ZIS has been used as photocatalyst for the partial oxidation of different aromatic alcohols to their corresponding aldehyde in water solution, under ambient conditions and simulated solar light irradiation. The photocatalytic performance of ZnIn2S4 was better than TiO2 P25. In the presence of ZIS for 4-methoxybenzyl alcohol, piperonyl alcohol, and benzyl alcohol, a selectivity towards the corresponding aldehyde of 99 % for a conversion of 46 %, 75 % for a conversion of 81 %, and 87 % for a conversion of 25 %, respectively, was obtained. For the same alcohols a selectivity of 19 % for a conversion of 41 %, 19 % for a conversion of 13 %, and 16 % for a conversion of 26 %, was observed in the presence of TiO2 P25.

Modular Access to Tetrasubstituted N−H Pyrroles by Catalytic 1,3‐Dipolar Cycloaddition of Azomethine Ylides and α,β‐Ynones

AbstractThe development of efficient synthetic strategies for the preparation of tetrasubstituted N−H pyrrole derivatives, especially in an environmentally benign fashion is important yet challenging. Herein, we report a copper(II)‐catalyzed tandem reaction involving 1,3‐dipolar cycloaddition of α,β‐ynones and glycine iminoesters, followed by copper(II)‐promoted oxidative (air) dehydrogenative aromatization, allowing de novo access to tetrasubstituted N−H pyrroles in up to 81 % yield under green reaction conditions. A possible reaction pathway is tentatively proposed. Finally, fully substituted pyrroles are available by N‐alkylation, and a preliminary phase‐transfer catalytic asymmetric N‐alkylation was also studied to give an axially chiral pyrrole.

Accessing 7,8-Dihydroquinoline-2,5-diones via Rh-Catalyzed Olefinic C-H Activation/[4+2] Cyclization.

Herein, we report a rhodium-catalyzed C-H activation/[4+2] cyclization reaction between α,β-unsaturated amides and iodonium ylides for the synthesis of novel 7,8-dihydroquinoline-2,5-diones and analogues. This protocol provides a series of pyridones fused with saturated cycles with good functional group compatibility, good water and air tolerance, and good to excellent yields under mild and green reaction conditions. Additionally, scale-up synthesis can be smoothly performed with as low as 0.25 mol % catalyst loading. Recycling experiments and different transformation experiments were also carried out to demonstrate the potential synthetic utility of this protocol.