Potential of green solvents as mobile phases in liquid chromatography

This review summarizes the key points and focuses on the use of green solvents in reversed-phase high-performance liquid chromatography. Ethanol, acetone, ethyl lactate, propylene carbonate, dimethyl carbonate, methyl acetate, Cyrene, and glycerol are examined as green solvents, with an emphasis on their properties related to HPLC applications. A total of 135 articles published between 1990 and the present, which utilize ethanol-water mobile phases in RP-HPLC, highlight the established use of ethanol as a green solvent for RP-HPLC. Although ethanol is often characterized by its high viscosity and UV absorbance, it remains one of the most commonly used green solvents. This study shows that approximately 30 % of the ethanol-based methods developed employed columns with reduced particle diameters, without the need for column heating. In 26 % of cases, UV detection was used, even at wavelengths egal to or below 220 nm. However, ethanol's volatility and flammability pose risks of operator exposure and fire hazards. Consequently, alternative solvents have been explored to mitigate these issues. Acetone, with over 20 years of use, presents similar safety concerns, compounded by its high UV absorbance. Recent advances in greener solvents, such as Cyrene, glycerol, and natural deep eutectic solvents, have been investigated to address VOC concerns in HPLC. However, these solvents still face challenges, including UV absorption, immiscibility with water, high viscosity, and limited availability in HPLC-grade quality. Therefore, additional research is needed to facilitate their broader application.

Colourful Protection: Challenges and Perspectives of Antibacterial Pigments Extracted from Bacteria for Textile Applications

Bacterial pigments have gained significant attention across multiple industries due to their natural hues and unique functional properties. Beyond coloration, some of these pigments exhibit antibacterial activity, making them particularly valuable in the textile industry as sustainable alternatives to synthetic antimicrobial treatments. Bacteria produce a vast array of pigments through diverse biosynthetic pathways, which reflect their metabolic adaptability and ecological roles. These pathways are influenced by environmental factors such as pH, temperature, and nutrient availability. Key pigments, including carotenoids, melanin, violacein, and prodigiosin, are synthesised through distinct mechanisms, often involving tightly regulated enzymatic reactions. For example, carotenoid biosynthesis relies on isoprenoid precursors, while melanin formation involves the oxidation of aromatic amino acids. Understanding these pathways provides insights into bacterial survival strategies, stress responses, and interactions with their environment. This review examines the dyeing potential of bacterial pigments on natural and synthetic fabrics, highlighting advancements in environmentally friendly extraction methods to minimise the ecological impact. Additionally, it explores safety, biocompatibility, and industrial challenges associated with bacterial pigment applications. Finally, future perspectives on integrating these pigments into various industries are discussed, emphasising their potential as bio-based solutions for sustainable and functional materials.

Exploring alternative solvents to n-hexane for green extraction of lipid from camellia oil cakes

Camellia oleifera Abel. is an important woody oilseed tree to help increase the self-sufficiency rate. In this study, lipid extraction focuses more on the solvent extraction of Camellia seed oil (CO) cakes rather than conventional cold pressing, where the performance of candidate alternative green solvents selected from hurdle technology was first evaluated. Compared to n-hexane (89.50 ± 0.00 %) and subcritical n-butane (83.75 ± 0.43 %), 2-methyloxolane (2-MeOx) performed the best with the comprehensive consideration of extraction ratio (94.79 ± 0.00 %), lipid composition and environmental impact (0.38 ± 0.07 kg of CO2 emission). Intriguingly, 2-MeOx exhibited the highest diffusion rate at both 25 °C and 55 °C in the extraction kinetic study, which could also extract the highest total phenolic contents (351.6 ± 0.02 mg GAE/kg dw) corresponding to its best oxidative stability. Besides, Hansen solubility modeling could help better understand the dissolving mechanism. 2-MeOx was demonstrated as the optimal alternative bio-based solvent to n-hexane with comparable extractability and selectivity in the CO extraction.

Aldehyde-Stabilization Strategies for Building Biobased Consumer Products around Intact lignocellulosic Structures

Dwindling fossil resources and their associated environmental concerns have increased interest in biobased products. In particular, many approaches to convert lignocellulosic biomass into small-molecule building blocks are being explored via thermal, chemical, and biological processes. Depending on their structure, these molecules can be used as direct (i.e., drop-in) or indirect (different molecule from what is used today) substitutes for petrochemicals. In all such cases, biomass must be deconstructed, which involves the depolymerization of lignin and polysaccharides as well as their further transformation to produce these substitutes. Deconstruction often requires harsh conditions that cause degradation, and further upgrading implies multiple conversion steps, especially for drop-in molecules, all of which lead to low atom economy. Our group has developed an aldehyde-stabilization strategy that facilitates the depolymerization of lignocellulose to monomers in high yields by stabilizing intermediates under biomass deconstruction conditions. This strategy has now been adapted to prepare indirect substitutes for petrochemicals with very high atom economy including biobased solvents, plastic precursors, adhesives, and surfactants, which have widespread applications in modern society.In this Account, we first introduce the function of aldehydes using formaldehyde (FA) as an example. Specifically, we discuss their role in assisting lignin isolation and their ability to stabilize lignin by looking at the lignin monomer yields that can be obtained after hydrogenolysis of the associated aldehyde-functionalized lignin. Highly selective production of lignin monomers was achieved using acetaldehyde (AA) or propionaldehyde (PPA) as a stabilization reagent via either reductive or oxidative depolymerization. In a typical FA-assisted fractionation, hemicellulose was directly converted into diformylxylose (DFX), while cellulose with properties similar to those obtained by organosolv was isolated but could be converted to diformyl-glucose isomers (DFGs) by further hydrolysis. These stable molecules provide us a new method to preserve sugar molecules that often degrade during acidic fractionation, which will be discussed in Section 3. Besides, DFX can also be used as a green solvent (Section 4), while FA-lignin exhibits excellent adhesion properties for plywood preparation (Section 5). Biobased glyoxylic acid (GA) was used to convert hemicellulose into a high yield of dimethylglyoxylic-acid-xylose (DMGX), a terephthalic acid (TA) substitute for bioplastics production (Section 6), while GA-lignin demonstrates great amphiphilic properties and finds applications as surfactants in cosmetic products (Section 7). When fatty aldehydes were used as stabilization reagents, both lignin and hemicellulose were converted to surfactants by downstream defunctionalization (Section 7). We will also discuss the current limitations of this aldehyde-stabilization strategy for biomass utilization as well as potential solutions and improvements to said limitations. With this Account, we hope to spur further interest in aldehyde stabilization as a tool to deconstruct biomass and build new consumer products around functionalized and thus largely preserved natural structures.

Eco-friendly solvents in liquid-liquid microextraction techniques for biological and environmental analysis: a critical review

In recent years, green solvents have emerged as promising alternatives in the field of analytical chemistry, replacing conventional organic solvents known for their toxicity, volatility, and flammability. The combination of these solvents with liquid-liquid microextraction techniques has facilitated the development of simpler, faster, more economical, and environment-friendly methodologies for the analysis of samples of varying complexity. This review discusses the fundamental physicochemical properties and advantages of using deep eutectic solvents, ionic liquids, switchable-hydrophilicity solvents, supramolecular solvents, and surfactants as extractants. Furthermore, analytical methods based on liquid-liquid microextraction techniques developed in the last 5 years for the determination of organic compounds and metals in biological and environmental samples are presented and discussed, highlighting their applications and benefits to improve analytical performance and sustainability.

Alkyl 4-Alkoxyvalerates: Characterization and Application in Pd-Catalyzed Aminocarbonylation of Iodo(hetero)arene Compounds

The palladium-catalyzed aminocarbonylation is one of the most effective methods for the synthesis of carboxamides having great importance. Replacing fossil-based organic solvents in this routinely used catalytic protocol with biomass-derived media is crucial for developing environmentally safe alternatives and towards sustainability considerations. In this study, the open-chain derivatives of bio-originated substance γ-valerolactone i. e. alkyl 4-alkoxyvalerates (alkyl: methyl, ethyl, and propyl) were characterized and tested as potential polar aprotic alternatives of fossil-based common N,N-dimethylformamide (DMF) in aminocarbonylation protocols. First, the temperature-dependent physicochemical properties of alkyl 4-alkoxyvalerates were determined. Based on their characteristics, methyl 4-methoxyvalerate (Me-4MeOV) was selected and introduced in the Pd-catalyzed aminocarbonylation of iodobenzene and morpholine as a model reaction, and an optimization study was carried out. Using the optimized conditions, several substituted iodobenzenes, as well as heteroaryl iodides, were successfully applied resulting in the target carboxamides selectively in short reaction time. Furthermore, the aminocarbonylation of iodobenzene in the presence of various amines was also accomplished extending the scope of the carboxamides produced in this alternative medium. Considering our observations, such as high conversions (up to 95 %) in short reaction time and selective amide formation, it has been justified that Me-4MeOV could be an appropriate alternative medium in aminocarbonylation protocols.

High-performance delivery capsules co-assembled from lignin and chitosan with avermectin for sustainable pest management

Inexpensive biomass materials hold great potential for the development of green delivery systems aimed at improving the extremely low utilization efficiency of pesticides. However, current systems face challenges in achieving both high encapsulation rates and drug loading capacities. This study introduces a novel method using chitosan (CS) and sodium lignosulfonate (SL) to co-assemble with avermectin (AVM), a widely used hydrophobic pesticide, forming AVM-CS-SL micro-nano capsules. Engineered under optimized conditions of pH 5 and 40 °C, the capsules exhibit an AVM encapsulation efficiency of 84.27 % and a loading capacity of 90 %. The AVM-CS-SL capsules demonstrate multifunctional attributes that enhance pesticide application. The capsules, with an average diameter of 356 nm, facilitate stable embedding in leaf grooves and enable effective adhesion to leaf surfaces, thereby improving their resistance to wash-off by rain compared to conventional formulations. Their core-shell structure protects AVM from photodegradation, ensuring long-term stability and efficacy. The capsules also exhibit enhanced bioactivity, with higher mortality rates in Plutella xylostella larvae and low genotoxicity to Vicia faba plants. These findings highlight the strategy of developing multifunctional delivery systems by the co-assembled carrier materials with active ingredients, offering an effective solution for the sustainable development of society and environment.

Mixed Solvency Concept to Replace Harmful Organic Solvent: Recent Trends and Future Challenges in Formulation Development

Organic solvents are hazardous and should be replaced with less harmful alternatives. When developing a new formulation for a medicine with low aqueous solubility, improving its solubility might be a significant difficulty. According to the mixed solvency concept, a novel concept of solubilization, the solubility of poorly soluble drugs can be increased by dissolving them in a concentrated solution comprising various substances. Methods commonly used to improve solubility include complexation, pH modification, salt formation, hydrotropy, cosolvency, and micelle solubilization. By reducing the concentration of specific solubilizers, this method can be used to reduce the toxicity of solubilizers in various formulations of poorly soluble medicines. This review aims to provide scientists with a fresh concept for enhancing medication solubility. The benefits and drawbacks of currently available green solvents have been analyzed as potential replacements for traditional solvents. Some examples of these solvents are bio-based solvents like ethanol, methanol, and cyrene; d-limonene; deep eutectic solvents such as ionic liquids and natural deep eutectic solvents; supercritical fluids; subcritical water; surfactant-based solutions like hydrotopes and supramolecular solvents; and deep eutectic solvents like cyrene.

Structural characterization and physicochemical properties of different hydrophilic natural deep eutectic solvents

To overcome the toxic nature of organic solvents, scientific interest in the use of green solvents, particularly natural deep eutectic solvents (NADES), has increased over the past decade, leading to new applications in the food, nutraceutical, pharmaceutical, and cosmetic industries. Understanding the physicochemical properties and molecular interactions of NADES is essential for uncovering new potential applications in these fields. In this study, several lactic and citric acid-based NADES, as well as chloride choline- and urea-based NADES, were evaluated for their physicochemical properties, including density, pH, viscosity, conductivity, and refractive index. Additionally, nuclear magnetic resonance (NMR), and in particular nuclear Overhauser enhancement spectroscopy (NOESY), was employed to investigate the intermolecular interactions between the NADES components to confirm the formation of the eutectic mixture. The extraction efficiency of the confirmed NADES was tested for extracting polyphenols as a proof of concept to highlight their relationship with the measured properties. Lactic and choline chloride-based NADES provided the highest extraction yields. These results were also compared with the predicted extraction capabilities of each NADES provided by the COSMO-RS software.

Efficient synthesis of α-aminophosphonates using magnetically retrievable ionic nanocatalysts under ultrasound acceleration

Magnetic supported ionic liquids are a unique subclass of ionic liquids that possess the ability to respond to external magnetic fields, combining the advantageous properties of traditional ILs with this magnetic responsiveness. A novel magnetic ionic nanocatalyst of Fe3O4@SiO2@CPTMS-DTPA was prepared by anchoring an ionic liquid, CPTMS-DTPA, onto the surface of silica-modified Fe3O4. The morphology, chemical structure and magnetic property of the magnetic ionic nanocatalyst structure was characterized using scanning electron microscopy, X-ray powder diffraction, Fourier transformation infrared spectroscopy, vibrating sample magnetometer, and thermogravimetric analysis. The results confirmed the successful attachment of the ionic liquid to the magnetic substrate. Subsequently, the magnetic nanocatalyst was employed for the green synthesis of α-aminophosphonate derivatives. The synthesis was achieved via a one-pot, three-component reaction involving various aldehydes, amines, and different trialkyl(aryl) phosphite derivatives. The reactions were conducted under ultrasound conditions for a duration of 10-25 min, resulting in good to excellent product yields (64-97%). Its recyclability was tested for up to five cycles using magnetic separation which makes it a highly efficient method for quickly separating catalysts from the reaction medium without compromising catalytic activity.

Build-a-Bio-Strip: An Online Platform for Rapid Toxicity Assessment in Chemical Synthesis

The increasing need to understand and control the environmental impact of chemical processes has revealed the challenge in efficient evaluation of toxicity of the vast number of chemical compounds and their varying effects on biological systems. In this study, we introduce "Build-a-bio-Strip", a novel online service designed to carry out a quick initial analysis of the toxic impact of chemical processes. This platform enables users to automatically generate toxicity characteristics of chemical reactions using their own data on cytotoxicity or median lethal doses of the substances involved or computational predictions based on SMILES strings. The service calculates the toxicity metrics such as bio-Factors and cytotoxicity potentials, which can be used to identify the substances with significant contributions to the overall toxicity of a particular process. This facilitates the selection of safer synthetic routes and the optimization of chemical processes from a toxicity perspective. "Build-a-bio-Strip" represents a step toward safer and more sustainable chemical practices. It is available free-of-charge at http://app.ananikovlab.ai:8080/.

Palladium nanoparticle catalyzed synthesis of indoles via intramolecular Heck cyclisation

A system utilizing palladium(II)-PEG has been devised for the intramolecular Heck cyclization of N-vinyl and N-allyl-2-haloanilines. The synthesis of a variety of indoles, including 2,3-diester substituted ones and 3-methyl indoles, has been accomplished using this catalytic system. The N-vinyl starting materials are obtained by the aza-Michael addition of 2-haloanilines with alkynecarboxylate esters, which, upon cyclization, yield ester-substituted indoles. Conversely, N-allyl-2-haloanilines yield 3-methylated indoles as the major products. The high activity of the system is owed to the in situ generation of Pd nanoparticles.

Catalytic Transformation of Carbohydrates into Renewable Organic Chemicals by Revering the Principles of Green Chemistry

Adherence to the principles of green chemistry in a biorefinery setting ensures energy efficiency, reduces the consumption of materials, simplifies reactor design, and rationalizes the process parameters for synthesizing affordable organic chemicals of desired functional efficacy and ingrained sustainability. The green chemistry metrics facilitate assessing the relative merits and demerits of alternative synthetic pathways for the targeted product(s). This work elaborates on how green chemistry has emerged as a transformative framework and inspired innovations toward the catalytic conversion of biomass-derived carbohydrates into fuels, chemicals, and synthetic polymers. Specific discussions have been incorporated on the judicious selection of feedstock, reaction parameters, reagents (stoichiometric or catalytic), and other synthetic auxiliaries to obtain the targeted product(s) in desired selectivity and yield. The prospects of a carbohydrate-centric biorefinery have been emphasized and research avenues have been proposed to eliminate the remaining roadblocks. The analyses presented in this review will steer to developing superior synthetic strategies and processes for envisaging a sustainable bioeconomy centered on biomass-derived carbohydrates.

Efficient and promising oxidative desulfurization of fuel using Fenton like deep eutectic solvent

Oxidative desulfurization (ODS) has emerged as a prominent technique for the removal of sulfur compounds from fuels, aiming to comply with stringent environmental regulations and minimize sulfur dioxide emissions. Herein, Fenton-like deep eutectic solvents (DESs) were synthesized as a catalyst and reaction medium and their application for the ODS process was investigated. The study encompassed the optimization of DES composition, reaction conditions, and the influence of different parameters on the desulfurization efficiency. The experimental findings demonstrated that the Fenton-like DES exhibited outstanding catalytic activity in the oxidative desulfurization of fuel. The optimized conditions involved conducting the reaction at room temperature for 2.5 h, using 200 mg of the prepared DES (HNFM-FeCl4) as both the extraction solvent and catalyst. An oxidant-to-sulfur (O/S) ratio of approximately 3:1 was maintained, with a 30 wt% H2O2 solution utilized as the oxidant. The analysis of the reaction products using GC-MS revealed a remarkable yield of 98% for dibenzothiophene sulfone. The DES provided a suitable medium for the reaction, enhancing the solubility and availability of sulfur compounds. The iron catalyst, in the presence of hydrogen peroxide, facilitated the oxidation of sulfur-containing compounds to their corresponding sulfones, which can be easily separated from the fuel phase. The DES catalysts exhibited stability and recyclability, making them suitable for practical applications in fuel desulfurization processes.

A thiol-ene mediated approach for peptide bioconjugation using 'green' solvents under continuous flow

Flow chemistry has emerged as an integral process within the chemical sector permitting energy efficient synthetic scale-up while improving safety and minimising solvent usage. Herein, we report the first applications of the photoactivated, radical-mediated thiol-ene reaction for peptide bioconjugation under continuous flow. Bioconjugation reactions employing deep eutectic solvents, bio-based solvents and fully aqueous systems are reported here for a range of biologically relevant peptide substrates. The use of a water soluble photoinitiator, Irgacure 2959, permitted synthesis of glycosylated peptides in fully aqueous conditions, obviating the need for addition of organic solvents and enhancing the green credentials of these rapid, photoactivated, bioconjugation reactions.

Investigation of alternative two-phase solvent systems for purification of natural products by centrifugal partition chromatography

INTRODUCTION

Centrifugal partition chromatography (CPC) is a liquid-liquid chromatography characterised by its solvent flexibility. The compounds undergoing separation are subjected to a continuous partition process between two immiscible phases in a column space free of solid support. In the context of green chemistry, it is important to substitute halogenated and petroleum-based solvents commonly used in purification processes.

OBJECTIVES

The main goal of the current study was to replace classical solvents used in CPC (e.g., hexane and methanol) by green and renewable alternatives.

METHODS

Solvents were first selected based on literature. Their commercial availability, price, recyclability, toxicity and ability to form two phases were particularly sought after.

KEY FINDINGS

The new two-phase solvent systems were evaluated for the purification of two compounds of interest: piperine and cannabidiol. Using these alternative two-phase solvent systems allows us to isolate natural products with a high purity level (> 95%).

CONCLUSION

Substituting petroleum-based solvents with bio-sourced, renewable alternatives reduces the environmental impact of CPC. Herein, new biphasic solvent systems were built using hexamethyldisiloxane, ethyl isobutyrate and 2-methyl tetrahydrofuran in combination with ethanol and water. Furthermore, this research provides a scientific basis for developing new and sustainable solvent systems in CPC.

Emerging green synthetic routes for thiazole and its derivatives: Current perspectives

This review article provides an overview of the green synthesis of thiazole derivatives, emphasizing sustainable and environmentally friendly methodologies. Thiazole derivatives possess significant value and find diverse applications across various fields. However, conventional synthesis methods often involve hazardous reagents and generate substantial waste, posing environmental concerns. The green synthesis of thiazole derivatives employs renewable starting materials, nontoxic catalysts, and mild reaction conditions to minimize environmental impact. Innovative techniques such as microwave irradiation, ultrasound synthesis, green solvents, a green catalyst-based approach, and mechanochemistry-mediated synthesis are employed, offering advantages in terms of scalability, cost-effectiveness, and purification simplicity. The resulting thiazole derivatives exhibit comparable or enhanced biological activities, showcasing the feasibility and practicality of green synthesis in drug discovery. This review paper underscores the importance of sustainable approaches in functional molecular synthesis and encourages further research in this domain.

Multi-Functional Organofluoride Catalysts for Polyesters Production and Upcycling Degradation

The production and degradation of polyesters are two crucial processes in polyester materials' life cycle. In this work, multi-functional organocatalysts based on fluorides for both processes are described. Organofluorides were developed as catalysts for ring-opening polymerization of lactide (lactone). Compared with a series of organohalides, organofluoride performed the best catalytic reactivity because of the hydrogen bond interaction between F- and alcohol initiator. The Mn values of polyester products could be up to 72 kg mol-1 . With organofluoride catalysts, the ring-opening copolymerization between various anhydrides and epoxides could be established. Furthermore, terpolymerization of anhydride, epoxide, and lactide could be constructed by the self-switchable organofluoride catalyst to yield a block polymer with a strictly controlled polymerization sequence. Organofluorides were also efficient catalysts for upcycling polyester plastic wastes via alcoholysis. Mixed polyester materials could also be hierarchically recycled.

Copolymerization of ethylene and isoprene via silicon bridge metallocene [rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2] catalyst: A new way to control the composition and microstructure of copolymers

The copolymerization of ethylene (E) with isoprene (Ip) was performed catalyzed by a symmetrical catalyst exhibiting a silicon bridge [rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 with the combination of borate/TIBA activator. The effect of cocatalyst, Ip concentration, and polymerization temperature on the activity, molecular weight (Mw), distribution (MWD), comonomer composition, chain structure (regio- and stereoselectivity), and resulting side reactions were logically addressed. Gel-permeation chromatography (GPC) was used to characterize the Mw and polydispersity, while nuclear magnetic resonance (NMR) was employed for the chain structure of the polymers. The catalytic activity was significantly lower by increasing the Ip concentration in the feed, and the isoprene content in resulting polymers was lower under the reaction condition, leading to higher activity. Insertion of isoprene units in polymer structure demonstrates the higher regioselectivity for the 3,4 connections than the 1,4 connections and is expected to be a high-resistance polymer against acids. The MWD presented monomodal even with a higher concentration (1.44 mol/L) and did not appear as low Mw peaks of Ip. The Mw was higher with a broader MWD when purely TIBA was used as a cocatalyst, and it significantly reduced and presented a narrowed MWD with TEA in the cocatalyst. The higher efficiency of the catalyst for the higher insertion of Ip (C=C double bond) effectively modifies the polymer backbone. It is expected to be a promising candidate for easily degradable and favorable solutions for solving environmental problems caused by PE. wastes.

Sustainability in Drug and Nanoparticle Processing

The formulation of drugs in poly(lactic-co-glycolic acid) (PLGA) nanoparticles can be accomplished by various methods, with nanoprecipitation and nanoemulsion being among the most commonly used manufacturing techniques to provide access to high-quality nanomaterials with reproducible quality. Current trends turned to sustainability and green concepts leading to a re-thinking of these techniques, particularly as the conventional solvents for the dissolution of the polymer suffer from limitations like hazards for human health and natural environment. This chapter gives an overview about the different excipients used in classical nanoformulations with a special focus on the currently applied organic solvents. As alternatives, the status quo of green, sustainable, and alternative solvents regarding their application, advantages, and limitations will be highlighted as well as the role of physicochemical solvent characteristics like water miscibility, viscosity, and vapor pressure for the selection of the formulation process, and for particle characteristics. New alternative solvents will be introduced for PLGA nanoparticle formation and compared regarding particle characteristics and biological effects as well as for in situ particle formation in a matrix consisting of nanocellulose. Conclusively, new alternative solvents are available that present a significant advancement toward the replacement of organic solvents in PLGA nanoparticle formulations.

Sustainable ionic liquids-based molecular platforms for designing acetylcholinesterase reactivators

We report a green chemistry approach for preparation of oxime-functionalized ILs as AChE reactivators: amide/ester linked IL, l-alanine, and l-phenylalanine derived salts bearing pyridinium aldoxime moiety. The reactivation capacities of the novel oximes were evaluated towards AChE inhibited by typical toxic organophosphates, sarin (GB), VX, and paraoxon (PON). The studied compounds are mostly non-toxic up to the highest concentrations screened (2 mM) towards Gram-negative and Gram-positive bacteria cell lines and both filamentous fungi and yeasts in the in vitro screening experiments as well as towards the eukaryotic cell (CHO-K1 cell line). Introduction of the oxime moiety in initially biodegradable structure decreases its ability to biodegradation. The compound 3d was shown to reveal remarkable activity against the AChE inhibited by VX, exceeding conventional reactivators 2-PAM and obidoxime. The regularities on antidotal activity, cell viability, plasma stability, biodegradability as well as molecular docking study of the newly synthesized oximes will be used for further improvement of their structures.

Novel Eco-friendly, One-Pot Method for the Synthesis of Kynurenic Acid Ethyl Esters

The synthesis of kynurenic acid derivatives with potential biological effect was investigated and optimized for one-batch, two-step microwave-assisted reactions. Utilizing both chemically and biologically representative non-, methyl-, methoxy-, and chlorosubstituted aniline derivatives, in catalyst-free conditions, syntheses of seven kynurenic acid derivatives were achieved in a time frame of 2-3.5 h. In place of halogenated reaction media, tuneable green solvents were introduced for each analogue. The potential of green solvent mixtures to replace traditional solvents and to alter the regioisomeric ratio regarding the Conrad-Limpach method was highlighted. The advantages of the fast, eco-friendly, inexpensive analytic technique of TLC densitometry were emphasized for reaction monitoring and conversion determination in comparison to quantitative NMR. Moreover, the developed 2-3.5 h syntheses were scaled-up to achieve gram-scale products of KYNA derivatives, without altering the reaction time in the halogenated solvent DCB and more importantly in its green substitutes.

Sustainable Phenylalanine-Derived SAILs for Solubilization of Polycyclic Aromatic Hydrocarbons

The solubilization capacity of a series of sustainable phenylalanine-derived surface-active ionic liquids (SAILs) was evaluated towards polycyclic aromatic hydrocarbons-naphthalene, anthracene and pyrene. The key physico-chemical parameters of the studied systems (critical micelle concentration, spectral properties, solubilization parameters) were determined, analyzed and compared with conventional cationic surfactant, CTABr. For all studied PAH solubilization capacity increases with extension of alkyl chain length of PyPheOC_n SAILs reaching the values comparable to CTABr for SAILs with n = 10-12. A remarkable advantage of the phenylalanine-derived SAILs PyPheOC_n and PyPheNHC_n is a possibility to cleave enzymatically ester and/or amide bonds under mild conditions, to separate polycyclic aromatic hydrocarbons in situ. A series of immobilized enzymes was tested to determine the most suitable candidates for tunable decomposition of SAILs. The decomposition pathway could be adjusted depending on the choice of the enzyme system, reaction conditions, and selection of SAILs type. The evaluated systems can provide selective cleavage of the ester and amide bond and help to choose the optimal decomposition method of SAILs for enzymatic recycling of SAILs transformation products or as a pretreatment towards biological mineralization. The concept of a possible practical application of studied systems for PAHs solubilization/separation was also discussed focusing on sustainability and a green chemistry approach.

Green-Efficient Enzymatic Synthesis and Characterization of Liposoluble 6'/6″-O-Lauryl Phenolic Glycosides with Enhanced Intestinal Permeability

Arbutin, salidroside, polydatin, and phlorizin are typically natural bioactive phenolic glycosides. To improve the liposolubility and bioavailability, highly liposoluble derivatives including 6'-O-lauryl arbutin, 6'-O-lauryl salidroside, 6″-O-lauryl polydatin, and 6″-O-lauryl phlorizin were efficiently synthesized by enzymatic acylation in a green solvent 2-MeTHF. Their reaction conversions reached 84.4, 99.5, 99.8, and 89.1%, respectively, when catalyzed by Lipozyme 435 at 20 mg/mL at 50 °C. As expected, the derivatives had high log P (1.66-2.37) and retained good antioxidant activity, making them potential alternatives to butylated hydroxytoluene (BHT) and tert-butyl-hydroquinone (TBHQ) in lipid systems. Then, the intestinal permeability characteristics and metabolism of phenolic glycosides and their derivatives were investigated based on Caco-2 monolayers. The permeability of polydatin and phlorizin was mainly through active transport, but that of arbutin and salidroside involved both passive diffusion and active uptake. The acylated derivatives suffered from severe CES-mediated hydrolysis but exhibited a larger transported amount than phenolic glycosides.

Molecular design and experimental study of deep eutectic solvent extraction of keratin derived from feathers

Feather keratin has a complex structure, hard texture and must be treated to improve its bioavailability. In this paper, according to the designability of DES, some deep eutectic solvents (DESs) were prepared to degrade feathers and extract keratin. Calculations by quantum chemical methods showed that DESs were considered molecular scissors with the ability to break initial hydrogen bonds and form new bonds only when the Gibbs free energy change for the degradation process was ΔG < 0, i.e., hydrogen binding energy ΔE < -0.3038 kcal/mol. Then, the degradation mechanism was predicted to provide guidance for the molecular design of DES. Finally, experimental results showed that the same ratio of choline chloride-based DESs had higher catalytic performance, in which [ChCl][P][ZnCl₂] 1:5:2 was used with a high yield of keratin of 85.46 %. DES had a high catalytic performance after multiple recycling cycles and this method has no H₂S gas generation, which improves the atomic utilization.

Application of Recently used Green Solvents in Sample Preparation Techniques: A Comprehensive Review of Existing Trends, Challenges, and Future Opportunities

Green solvents (GSs) has gained significant attention in recent years due to their potential as safer and more sustainable alternatives to traditional organic solvents. Solvents are used in a wide range of applications, from industrial processes to everyday products. Solvent emissions and losses can have a significant impact on the environment and human health, which is why many initiatives are being undertaken to get rid of or switch to eco-friendly alternatives. A key area of green chemistry that led to the concept of "green" solvents is the development of alternative solvents that are less toxic and more environmentally friendly than traditional organic solvents. The advantages of using green solvents over conventional ones are their environmental friendliness, biocompatibility, biodegradability, and simplicity of preparation. Different sample preparation techniques have successfully utilized green solvents to offer a sustainable separation media for the extraction of a variety of inorganic and organic compounds which are crucial for research in environmental samples. Recent developments in green analytical chemistry (GAC) have focused on how to prepare and use samples using environmentally sustainable solvents. The current study covers the advance and currently used green solvents with an emphasis on environmentally friendly sample preparation methods. This review aims to briefly summarize the current state of knowledge about the use of green solvents particularly ionic liquids, deep eutectic solvents and switchable solvents (SSs) with the perspective of GAC in sample preparation methods.

New imidazolium-based ionic liquids for mitigating carbon steel corrosion in acidic condition

Two environmentally friendly inhibitors of imidazolium-based ionic liquids namely 3-benzyl-1-hexadecyl-1H-imidazol-3-ium chloride (IL-H), and 3-(4-chlorobenzyl)-1-hexadecyl-1H-imidazol-3-ium chloride (IL-Cl) were manufactured and their chemical structures were confirmed by spectra tools (FT-IR, and 1H NMR). The utilizing of these two new ionic liquids as green corrosion inhibitors for low carbon steel (LCS) in 1.0 M HCl under altered experimental conditions. Mass loss (ML), potentiodynamic polarization (PP), AC impedance spectroscopy (EIS) and surface morphology are take place in this study. The protection performance found to increase with increasing ionic liquid dose and temperature, reaching 92.9% and 95.1% for IL-H and IL-Cl at 120 ppm, respectively. Based on the PP records, the investigated ionic liquids behave as mixed-type inhibitors, influencing both anodic and cathodic responses. The inhibitory activity from these explored ionic liquids was stimulated by their adsorption on the effective surfaces of the steel surface in accordance with the Langmuir adsorption isotherm. The Density Functional Theory (DFT) method is used to analyze the relationship between quantum chemical calculations and the protection efficiency of ionic liquids.

Does variation in composition affect dynamics when approaching the eutectic composition?

Deep eutectic solvent is a mixture of two or more components, mixed in a certain molar ratio, such that the mixture melts at a temperature lower than individual substances. In this work, we have used a combination of ultrafast vibrational spectroscopy and molecular dynamics simulations to investigate the microscopic structure and dynamics of a deep eutectic solvent (1:2 choline chloride: ethylene glycol) at and around the eutectic composition. In particular, we have compared the spectral diffusion and orientational relaxation dynamics of these systems with varying compositions. Our results show that although the time-averaged solvent structures around a dissolved solute are comparable across compositions, both the solvent fluctuations and solute reorientation dynamics show distinct differences. We show that these subtle changes in solute and solvent dynamics with changing compositions arise from the variations in the fluctuations of the different intercomponent hydrogen bonds.

Recent Advances in Greener Asymmetric Organocatalysis Using Bio-Based Solvents

Efficient synthetic methods that avoid the extensive use of hazardous reagents and solvents, as well as harsh reaction conditions, have become paramount in the field of organic synthesis. Organocatalysis is notably one of the best tools in building chemical bonds between carbons and carbon-heteroatoms; however, most examples still employ toxic volatile organic solvents. Although a portfolio of greener solvents is now commercially available, only ethyl alcohol, ethyl acetate, 2-methyltetrahydrofuran, supercritical carbon dioxide, ethyl lactate, and diethyl carbonate have been explored with chiral organocatalysts. In this review, the application of these bio-based solvents in asymmetric organocatalytic methods reported in the last decade is discussed, highlighting the proposed mechanism pathway for the transformations.

Activity-Based Models to Predict Kinetics of Levulinic Acid Esterification

The solvent is of prime importance in biomass conversion as it influences dissolution, reaction kinetics, catalyst activity and thermodynamic equilibrium of the reaction system. So far, activity-based models were developed to predict kinetics and equilibria, but the influence of the catalyst on kinetics has not been succesfully predicted by thermodynamic models. In this work, the thermodynamic model ePC-SAFT advanced was used to predict the activities of the reactants and of the catalyst at various conditions (temperature, reactant concentrations, γ-valerolactone GVL cosolvent addition, catalyst concentration) for the homogeneously acid-catalyzed esterification of levulinic acid (LA) with ethanol. Different kinetic models were applied, and it was found that the catalyst influence on kinetics could be predicted correctly by simultaneously solving the dissociation equilibrium of H₂ SO₄ catalyst along the reaction coordinate and by relating reaction kinetics to proton activity. ePC-SAFT advanced model parameters were only fitted to reaction-independent phase equilibrium data. The key reaction properties were determined by applying ePC-SAFT advanced to one experimental kinetic curve for a set of temperatures, yielding the reaction enthalpy at standard state Δ R H 0 = 11 . 48 k J m o l - 1 ${{\Delta }^{R}{H}^{0}=11.48\ kJ\ mo{l}^{-1}}$ , activation energy E A = 30 . 28 k J m o l - 1 ${{E}_{A}=30.28\ kJ\ mo{l}^{-1}}$ and the intrinsic reaction rate constant k=0.011 s^-1 at 323 K, which is independent of catalyst concentration. The new procedure allowed an a-priori identification of the effects of catalyst, solvent and reactant concentration on LA esterification.

Isolation of Pure Lignin and Highly Digestible Cellulose from Defatted and Steam-Exploded Cynara cardunculus

In this work, a three-step approach to isolate the main components of lignocellulosic cardoon, lignin and cellulose, was investigated. The raw defatted biomass, Cynara cardunculus, after steam explosion was subjected to a mild organosolv treatment to extract soluble lignin (L1). Then, enzymatic hydrolysis was performed to achieve decomposition of the saccharidic portion into monosaccharides and isolate residual lignin (L2). The fractionation conditions were optimized to obtain a lignin as less degraded as possible and to maximize the yield of enzymatic hydrolysis. Furthermore, the effect of the use of aqueous ammonia as an extraction catalyst on both fractions was studied. Each fraction was characterized by advanced techniques, such as elemental analysis and ³¹P nuclear magnetic resonance (NMR), ¹³C-¹H two-dimensional (2D)-NMR, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and UV-vis spectroscopies for lignin and X-ray diffraction (XRD), Klason compositional analysis, elemental analysis, and ATR-FTIR spectroscopy for cellulose-rich fractions. The impact of the cellulose-rich fraction composition and crystallinity was also correlated to the efficiency of the hydrolysis step, performed using the enzymatic complex Cellic CTec3.

Biopolymer - A sustainable and efficacious material system for effluent removal

Undesired discharge of various effluents directly into the aquatic ecosystem can adversely affect water quality, endangering aquatic and terrestrial flora and fauna. Therefore, the conceptual design and fabrication of a sustainable system for alleviating the harmful toxins that are discharged into the atmosphere and water bodies using a green sustainable approach is a fundamental standpoint. Adsorptive removal of toxins (∼99% removal efficacy) is one of the most attractive and facile approaches for cleaner technologies that remediate the environmental impacts and provide a safe operating space. Recently, the introduction of biopolymers for the adsorptive abstraction of toxins from water has received considerable attention due to their eclectic accessibility, biodegradability, biocompatibility, non-toxicity, and enhanced removal efficacy (∼ 80-90% for electrospun fibers). This review summarizes the recent literature on the biosorption of various toxins by biopolymers and the possible interaction between the adsorbent and adsorbate, providing an in-depth perspective of the adsorption mechanism. Most of the observed results are explained in terms of (1) biopolymers classification and application, (2) toxicity of various effluents, (3) biopolymers in wastewater treatment and their removal mechanism, and (4) regeneration, reuse, and biodegradation of the adsorbent biopolymer.

Concept for the valorization of cereal processing waste: Recovery of phenolic acids by using waste-derived tetrahydrofurfuryl alcohol and biochar

Valorization of agro-food waste by converting it into a renewable resource plays a crucial role in a bio-based circular economy. Therefore, this study was designed to evaluate the suitability of distillery stillage (DS), which comes from alcohol production from cereals, for producing value-added products that can be used synergistically. The main objective was to investigate the usefulness of two substances for the recovery of phenolic acids, which have antioxidant activity, from the liquid fraction of DS: namely, tetrahydrofurfuryl alcohol (THFA) as a solvent and biochar as an adsorbent, both produced from the solid fraction of cereal processing waste. The effect of THFA concentration (80 and 100%) on phenolic acid yield in ultrasound-assisted extraction was studied. The solubilization predictions of phenolic compounds by the Hansen solubility parameters were in accordance with the experimental results: the yield of phenolic acids in the extracts was highest (3.76 μg g^-1 dry mass) with 80% THFA. Among the extracted phenolic acids, hydroxycinnamic acids predominated over hydroxybenzoic acids, which may affect the bioactive properties of the extracts and their future applications for industrial purposes. Phenolic acids from the extracts were adsorbed on 17-170 g biochar L^-1 and desorbed into water at 40-60 °C. The phenolic acid recovery was highest (∼92%) when the biochar dose was 85 g L^-1 and when desorption was performed at 50 °C. After adsorption/desorption, ∼95% of the antioxidant activity of the phenolic acids in the extracts was maintained. As biochar has a smaller specific surface area than commercial powdered activated carbon (PAC), the biochar dose should be about 5 times higher than an equivalent PAC dose for adsorption efficiency above 90%.

Azide-Alkyne Cycloaddition Catalyzed by Copper(I) Coordination Polymers in PPM Levels Using Deep Eutectic Solvents as Reusable Reaction Media: A Waste-Minimized Sustainable Approach

Two air-stable copper(I)-halide coordination polymers 1 and 2 with NNS and NNO ligand frameworks were synthesized and successfully utilized as efficient catalysts in an important organic reaction, namely, copper-catalyzed azide-alkyne cycloaddition, which is generally conducted in a mixture of water and organic solvents. The azide-alkyne "click" reaction was successfully conducted in pure water at r.t. under aerobic conditions. Other green solvents, including ethanol and glycerol, were also effectively used. Finally, deep eutectic solvents as green and sustainable reaction media were successfully utilized. In deep eutectic solvents, complete conversion with excellent isolated yield was achieved in a short period of time (1 h) with low catalyst loading (1 mol %) at r.t. Full conversion could also be achieved within 24 h with ppm-level (50 ppm) catalyst loading at 70 °C. Optimized reaction conditions were used for the syntheses of a large number of 1,4-disubstituted 1,2,3-triazoles with various functionalities. Triazole products were easily isolated by simple filtration. The reaction media, such as water and deep eutectic solvents, were recovered and recycled in three consecutive runs. The limited waste production is reflected in a very low E-factor (0.3-2.8). Finally, the CHEM21 green metrics toolkit was employed to evaluate the sustainability credentials of different optimized protocols in various green solvents such as water, ethanol, glycerol, and deep eutectic solvents.

Green nanostructured liquids for the analysis of urine in drug-facilitated sexual assault cases

In this work, we optimize and validate a simple, time-saving, and environmentally friendly sample preparation method based on supramolecular solvents (SUPRAS), green nanostructured liquids, for the extraction of selected drug-facilitated sexual assault (DFSA) substances from human urine. The methodology was fast and simple (stirring, centrifugation, and dilution). Cubosomic SUPRAS were formed by the addition of 1,2-hexanediol (200 μL) to 1.0 mL of human urine containing 1 M Na₂SO₄. SUPRAS extracts were analyzed by LC-MS/MS. The method was fully validated for 23 DFSA compounds including 10 benzodiazepines, 1 z-hypnotic drug, 5 amphetamine derivatives, 3 cocaine metabolites, and 4 miscellaneous compounds. Extraction efficiency varied between 79 and 119%, and matrix effects were acceptable (-14.3/+21.5) for 87% of the compounds. Method detection and quantification limits ranged from 0.003 to 0.75 ng/mL and from 0.01 to 2.50 ng/mL, respectively. These values were low enough for the established minimum required performance limits (MRPL) of these substances. This simple and green method has a great potential to be implemented for the monitoring of illegal drugs involved in DFSA cases by forensic laboratories.

Transition Metal Catalyzed Hiyama Cross-Coupling: Recent Methodology Developments and Synthetic Applications

Hiyama cross-coupling is a versatile reaction in synthetic organic chemistry for the construction of carbon-carbon bonds. It involves the coupling of organosilicons with organic halides using transition metal catalysts in good yields and high enantioselectivities. In recent years, hectic progress has been made by researchers toward the synthesis of diversified natural products and pharmaceutical drugs using the Hiyama coupling reaction. This review emphasizes the recent synthetic developments and applications of Hiyama cross-coupling.

N-heterocyclic Carbene Gold Complexes Active in Hydroamination and Hydration of Alkynes

Until the year 2000, gold compounds were considered catalytically inert. Subsequently, it was found that they are able to promote the nucleophilic attack on unsaturated substrates by forming an Au–π-system. The main limitation in the use of these catalytic systems is the ease with which they decompose, which is avoided by stabilization with an ancillary ligand. N-heterocyclic carbenes (NHCs), having interesting s-donor capacities, are able to stabilize the gold complexes (Au (I/III) NHC), favoring the exploration of their catalytic activity. This review reports the state of the art (years 2007–2022) in the nucleophilic addition of amines (hydroamination) and water (hydration) to the terminal and internal alkynes catalyzed by N-heterocyclic carbene gold (I/III) complexes. These reactions are particularly interesting both because they are environmentally sustainable and because they lead to the production of important intermediates in the chemical and pharmaceutical industry. In fact, they have an atom economy of 100%, and lead to the formation of imines and enamines, as well as the formation of ketones and enols, all important scaffolds in the synthesis of bioactive molecules, drugs, heterocycles, polymers, and bulk and fine chemicals.

Simple and modestly scalable synthesis of

The bio-derived platform molecule levoglucosenone (LGO, 1), which is the precursor to the green solvent Cyrene® (2), has been converted, at multi-gram scale, into its pseudo-enantiomer (iso-LGO, 2) and then reduced to iso-Cyrene (4). A less effective synthesis of this last compound from D-glucose is also described. Various physicochemical as well as certain toxicological properties of compound 4 are reported and compared to those established for the now commercially available Cyrene® (2). Such studies reveal that there are significant enough differences in the properties of the sustainably-derived Cyrene® (2) and isomer 4 (iso-Cyrene) to suggest they will exert complementary effects as solvents in a range of settings.

Solvent effects on the wood delignification with sustainable solvents

Solutions of a pure organic solvent acidified with 1% sulfuric acid, and some of their aqueous mixtures were used for lignin extraction in the Pinus radiata sawdust delignification. Organic acid solvents including acetic, lactic and citric acids as well as non-acidic compounds such as γ-valerolactone, 2-methyltetrahydrofuran, glycerol and ethylene glycol were studied. Crude lignin extractions yields (%) ranging between ca. 5-50% were obtained, from which ethylene glycol (33%), γ-valerolactone (48%) and propylene carbonate (52%) showed the greatest effectiveness. The effect of added water on the lignin extraction was investigated in mixtures of an organic solvent with a variable water content (75%w/w, 50% w/w, 25%w/w and 10% w/w) where it was observed that the yield of extraction decreased with the increased water content. Moreover, the purity of extracted lignins were analyzed by spectroscopic methods (UV and IR). Kamlet-Taft solvent polarity parameters, were determined with the solvatochromic probes 4-nitroaniline, N,N-diethyl-4-nitroaniline, Nile Red and 6-propionyl-2-N,N-dimethylaminonaphthalene (PRODAN), and then correlated to lignin extraction yields to explain the influence of the solute-solvent interactions on biomass delignification. A reasonable correlation was found between the medium polarizability-dipolarity π* and the effectiveness of the solvent mixture on the extraction of lignin wood.