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The exponentially increasing use of hazardous traditional organic solvents and catalysts for more accessible synthesis of important heterocycles useful for humankind in various fields, such as medicine, materials science, and agrochemicals, is having devastating impacts on the environment, are directly or indirectly affecting the structure and productivity of ecosystems. This has shifted the focus of the scientific community towards using eco-friendly and greener solvents, catalysts, materials, and methods for sustainable growth. As a result, there is a drive to change traditional techniques to environmentally sustainable processes by following the principle's of green chemistry. In this connection, the use of hazardous organic solvents and catalysts for synthesizing 1,2,3-triazoles is a global concern. Thus, newer methodologies were designed using eco-friendly catalysts and benign solvents such as ionic liquids (ILs) or water. The use of ILs in organic synthesis as a solvent and catalyst has attracted tremendous attention in recent years owing to their superior physiochemical properties, such as low vapor pressure, non-volatility, non-flammability, excellent conductivity, and electrochemical and thermal stability, thereby, increasing the reactivity, selectivity, catalyst recyclability, and other properties. In this review, authors have critically screened, divided, and summarized research articles into two significant sections: firstly, the synthesis of 1,2,3-triazoles from alkynes using ILs and secondly, the synthesis of 1,2,3-triazoles from substrate molecules other than alkynes using ILs. It is hoped that this review will stimulate scientists to adopt environmentally sustainable ILs as green solvents and catalysts for the synthesis of 1,2,3-triazole-based compounds. [ABSTRACT FROM AUTHOR]

Horseradish peroxidase (HRP) was immobilized in hybrid calcium alginate-gelatin hydrogel beads by entrapment. Then, organic solubility, metal ion compatibility, pH/temperature studies of the synthesized materials have been carried out. Hybrid beads (Ca-Alg@gel-HRP) were synthesized under optimum synthesis conditions with high yield and specific activity. The synthesized bead size was determined to be approximately 0.29 mm in diameter, hydrogel structure and transparent appearance. Accordingly, the optimum pH of free HRP and Ca-Alg@gel HRP was found to be pH 6 and 5 and the optimum temperature was found to be 40 °C and 60 °C respectively. For all identified metal ions except Fe2+, the Ca-Alg@gel HRP had a higher activity than the free HRP. In the presence of 1 mM Na+, Ca2+, Mg2+, Ba2+, Cu2+, Ni2+, Mn2+, Hg2+ ions, the activity increased by more than 20%. The relative activity was also approximately 153%, 150% and 145% in 2.5 mM chloroform, glycerol and DMF. Free enzyme activity was reduced by more than 30%. The Ca-Alg@gel HRP at room temperature and 4 °C retained most of its activity after 14 days. In cycle 5, it had half the activity. As a conclusion, it may have significant potential in a number of industrial processes, particularly in organic synthesis, because it is tolerant to metal ions and organic solvents and is a cheap, practical and simple immobilization method. [ABSTRACT FROM AUTHOR]

In situ electrochemical potential-induced fast synthesis the ultrathin MAF-4 membrane on polymer support with a satisfactory H 2 /CO 2 separation performance and excellent stability. [Display omitted] Metal-Organic Framework (MOF) membranes act as selective layers have offered unprecedented opportunities for energy-efficient and cost-effective gas separation. Searching for the green and sustainable synthesis method of dense MOF membrane has received huge attention in both academia and industry. In this work, we demonstrate an in situ electrochemical potential-induced synthesis strategy to aqueously fabricate Metal Azolate Framework-4 (MAF-4) membranes on polypropylene (PP) support. The constant potential can induce the heterogeneous nucleation and growth of MAF-4, resulting an ultrathin membrane with the thickness of only 390 nm. This high-quality membrane exhibits a high H 2 /CO 2 separation performance with the H 2 permeance as high as 1565.75 GPU and selectivity of 11.6. The deployment of this environment friendly one-step fabrication method under mild reaction conditions, such as low-cost polymer substrate, water instead of organic solvent, room temperature and ambient pressure shows great promise for the scale-up of MOF membranes. [ABSTRACT FROM AUTHOR]

Some of the latest technological developments involving chemistry in water are discussed. Although each advance bears little-to-no relationship to the others, in the composite they highlight the seemingly unlimited opportunities for discovering nature's secrets using water as the reaction medium. Thus, in addition to the environmental aspects driving this research, the benefits to be realized in making this switch away from reactions run in organic solvents and into an aqueous medium are clearly indicative of the future of synthetic organic chemistry. [ABSTRACT FROM AUTHOR]

Conducting electrochemical organic synthesis in/on whole water media is undoubtedly a highly green approach, which avoids the usage of organic solvents, and sometimes organic supporting electrolytes. In this review, the electrochemical organic syntheses in/on whole water environment are reviewed, especially including the reactions conducted both in organic solvent and water for comparisons. This review discussed anodic and cathodic reaction, respectively, including the C−H oxidation, hydroxylation, dehydrogenative cross coupling, functionalization of alkenes, cathodic oxidation, hydrogenation, reductive cross coupling, and so on. As the reduction of CO2, conversion biomass, and waste water disposal are frequently performed in water, and have already been reviewed recently. These topics are not included in this review. [ABSTRACT FROM AUTHOR]

This study uses a rapid tandem mass‐spectrometry method to determine water content in complex organic solutions. Emphasis is placed on trace‐water analysis by a fast and accurate alternative to the Karl–Fischer method. In this new method, water is captured by a charge‐labeled molecular probe. Water binds strongly with high specificity to the strongly electrophilic aldehyde site in a charge‐labelled molecule (N‐methylpyridinium); competitive binding by other analytes is effectively discriminated against in the mass‐measurement step. Quantitative determinations are made over a wide concentration range, 0.001 % (10 ppm) to 99 %, with better than 10 % relative standard deviation, along with short (1 min) analysis times using small sample volumes (several μL). Applications include water measurement in simple organic solvents, for example, deuterated solvents, as well as in complex mixtures, for example, organic reaction mixtures. Additionally, this method allows for water monitoring in levitated droplets. Mechanistic investigations into the impact of water on important chemical processes in organic synthesis and environmental science are reported. [ABSTRACT FROM AUTHOR]

This study uses a rapid tandem mass‐spectrometry method to determine water content in complex organic solutions. Emphasis is placed on trace‐water analysis by a fast and accurate alternative to the Karl–Fischer method. In this new method, water is captured by a charge‐labeled molecular probe. Water binds strongly with high specificity to the strongly electrophilic aldehyde site in a charge‐labelled molecule (N‐methylpyridinium); competitive binding by other analytes is effectively discriminated against in the mass‐measurement step. Quantitative determinations are made over a wide concentration range, 0.001 % (10 ppm) to 99 %, with better than 10 % relative standard deviation, along with short (1 min) analysis times using small sample volumes (several μL). Applications include water measurement in simple organic solvents, for example, deuterated solvents, as well as in complex mixtures, for example, organic reaction mixtures. Additionally, this method allows for water monitoring in levitated droplets. Mechanistic investigations into the impact of water on important chemical processes in organic synthesis and environmental science are reported. [ABSTRACT FROM AUTHOR]

The use of volatile solvents for organic synthesis is nowadays questioned due to their negative impact on the environnement. To develop sustainable and environmentally friendly methodologies, we propose to combine two green chemistry concepts: the use of bioinspired solvents: natural deep eutectic solvents (NaDES), and mechanochemistry. Using the Suzuki‐Miyaura coupling as a model reaction, we described an efficient mechanochemical method with NaDES as a LAG (liquid‐assisted grinding) additive with short reaction times and without any ligand or additional heating. A mechanochemical extraction was also used to reduce the amounts of extraction solvents and the total time of the synthesis process. [ABSTRACT FROM AUTHOR]

One of the efficient approaches to achieving net-zero greenhouse gas emissions is the 100% atom-economical conversion of the greenhouse gas carbon dioxide (CO2) to cost-effective, less toxic cyclic carbonates that can act as green solvents and abundant C1 synthon in organic synthesis. In this work, we have synthesized an Indium Metal–Organic Framework (MOF), functionalized with triazole MIL-68(In)-NHTr (Tr = 1-methylene-1,2,4-triazole) as a bifunctional catalyst for the synthesis of cyclic carbonates from epoxides with high yield (96%) and selectivity (100%) under solvent-free ambient reaction conditions (CO2 pressure 1 bar, temperature 50 °C, and reaction time 6 h). The synergistic acid–base effect of Indium SBU and the triazole of MIL-68(In)-NHTr make this a better catalyst than the conventional MIL-68(In)-NH2. This new catalyst was non-leachable and was reusable for six consecutive catalytic cycles without appreciable loss in the catalytic efficiency and crystallinity of the MOF framework. [ABSTRACT FROM AUTHOR]

In order to make sure that the reactions developed are truly catalyst-free in nature, it is important to take the following precautions when working on catalyst-free water-based reactions. 3 C-S Bond-Formation Reactions: Allenic Amides as the Electrophiles As mentioned earlier, click reactions involving Huisgen-type reactions have been used widely in chemical biology. However, many of the reported methods suffer from various drawbacks; these include the need to use toxic reagents/solvents, metal catalysts, or harsh reaction conditions and the poor atom-economy of the reactions. Keywords: catalyst-free reaction; biocompatibility; Mukaiyama aldol reaction; allenic amides; antibody-drug conjugates; green chemistry EN catalyst-free reaction biocompatibility Mukaiyama aldol reaction allenic amides antibody-drug conjugates green chemistry 1309 1316 8 07/11/23 20230725 NES 230725 Graph 1 Introduction The development of catalyst-free reactions that can work under biocompatible reaction conditions (aqueous media, pH 7.0, rt, etc.) is one of the most important goals in green chemistry and chemical biology. [Extracted from the article]

Over the last years, we observed a significant increase in the number of published studies that focus on the synthesis and characterization of deep eutectic solvents (DESs). These materials are of particular interest mainly due to their physical and chemical stability, low vapor pressure, ease of synthesis, and the possibility of tailoring their properties through dilution or change of the ratio of parent substances (PS). DESs, considered as one of the greenest families of solvents, are used in many fields, such as organic synthesis, (bio)catalysis, electrochemistry, and (bio)medicine. DESs applications have already been reported in various review articles. However, these reports mainly described these components' basics and general properties without focusing on the particular, PS-wise, group of DESs. Many DESs investigated for potential (bio)medical applications comprise organic acids. However, due to the different aims of the reported studies, many of these substances have not yet been investigated thoroughly, which makes it challenging for the field to move forward. Herein, we propose distinguishing DESs comprising organic acids (OA-DESs) as a specific group derived from natural deep eutectic solvents (NADESs). This review aims to highlight and compare the applications of OA-DESs as antimicrobial agents and drug delivery enhancers—two essential fields in (bio)medical studies where DESs have already been implemented and proven their potential. From the survey of the literature data, it is evident that OA-DESs represent an excellent type of DESs for specific biomedical applications, owing to their negligible cytotoxicity, fulfilling the rules of green chemistry and being generally effective as drug delivery enhancers and antimicrobial agents. The main focus is on the most intriguing examples and (where possible) application-based comparison of particular groups of OA-DESs. This should highlight the importance of OA-DESs and give valuable clues on the direction the field can take. [ABSTRACT FROM AUTHOR]

Multicomponent reactions are crucial for operating organic synthesis. In today's world, chemists concentrate on greener methodologies that cater to rising environmental concerns. Most conventional organic solvents are harsh on the environment, which can be addressed by environmentally and pocket‐friendly Deep eutectic solvents (DES). Organic synthesis via MCR in the presence of DES has resulted in the blend of green methodology and green solvent for organic transformations. Forasmuch as addressing the environmental concerns and developing higher heterocycles, our review focuses on the literature published on the DES‐mediated Multicomponent synthesis of N‐Heterocyclic compounds. [ABSTRACT FROM AUTHOR]

Biocatalytic transformations in organic synthesis often require the use of organic solvents to improve substrate solubility and promote the product formation. Halohydrin dehalogenases (HHDHs) are enzymes that catalyze the formation and conversion of epoxides, important synthetic class of compounds that are often sparingly soluble in water and prone to hydrolysis. In this study, the activity, stability, and enantioselectivity of HHDH from Agrobacterium radiobacter AD1 (HheC) in form of cell-free extract were evaluated in various aqueous-organic media. A correlation was discovered between the enzyme activity in the ring-closure reaction and logP of the solvent. Knowledge of such a relationship makes biocatalysis with organic solvents more predictable, which may reduce the need to experiment with a variety of solvents in the future. The results revealed a high enzyme compatibility with hydrophobic solvents (e.g., n-heptane) in terms of activity and stability. Regarding the HHDH applicability in an organic medium, inhibitions by a number of solvents (e.g., THF, toluene, chloroform) proved to be a more challenging problem than the protein stability, especially in the ring-opening reaction, thus suggesting which solvents should be avoided. In addition, solvent tolerance of the thermostable variant ISM-4 was also evaluated, revealing increased stability and to a lesser extent enantioselectivity compared to the wild-type. This is the first time such a systematic analysis has been reported, giving insight into the behavior of HHDHs in nonconventional media and opening new opportunities for the future biocatalytic applications. Key points: • HheC performs better in the presence of hydrophobic than hydrophilic solvents. • Enzyme activity in the PNSHH ring-closure reaction is a function of the logP. • Thermostability of ISM-4 variant is accompanied by superior solvent tolerance. [ABSTRACT FROM AUTHOR]

Acetonitrile is commonly used as an organic solvent and can also be used as an important intermediate in organic synthesis. Its widespread use has led to the development of new methods for the synthesis of a variety of important compounds. In the past decades, the conversion reactions of acetonitrile as a building block have become one of the most-attractive fields in organic synthesis. Especially in the field of electrochemical conversions involving acetonitrile, due to its good conductivity and environmentally friendly features, it has become a powerful and compelling tool to afford nitrogen-containing compounds or nitrile-containing compounds. In this review, we mainly discuss the research progress involving acetonitrile in the past five years, covering both conventional synthesis methods and electrochemical synthesis. Besides, a detailed discussion of the substrate scope and mechanistic pathways is provided. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

During the last decade, a wide spectrum of applications and advantages in the use of deep eutectic solvents for promoting organic reactions has been well established among the scientific community. Among these synthetic methodologies, in recent years, various examples of biocatalyzed processes have been reported, making use of eutectic mixtures as reaction media, as an improvement in terms of selectivity and sustainability. This review aims to show the newly reported protocols in the field, subdivided by reaction class as a 'toolbox' guide for organic synthesis. [ABSTRACT FROM AUTHOR]

The conventional synthesis of porous carbon materials is primarily relied on the activation and template process. This work successfully develops a one-step method for preparing amorphous porous carbon nanoparticles (APCNs) with a high specific surface area (SSA) in organic solvents under ambient atmosphere. The APCNs are formed mainly by the reaction of ferrocene with ammonium chloride at only 180 °C for 1 h in different solvents. Several ferrocene derivatives and KOH activation are also utilized to improve the textural properties of the APCNs. It is found that the high solubility of (C 5 H 5) 2 Fe and FeCl 3 ·6H 2 O in a solvent is the most essential factor associated with the decrease of carbon nanoparticle size. The smaller the nanoparticle size, the larger the SSA of APCNs. The APCNs prepared in phenoxyethanol have a median size of 32.74 nm, exhibiting an SSA of 689 m2/g. The high solubility of NH 4 Cl can also contribute to reducing the nanoparticle size. The binary solvent consisting of phenoxyethanol and glycol has an excellent solubility for (C 5 H 5) 2 Fe, FeCl 3 ·6H 2 O, and NH 4 Cl, in which the prepared APCNs have a median size 11.48 nm and a higher SSA of 936 m2/g. Besides, the benzoyl substituted group on the cyclopentadiene can facilitate formation of small mesopores. The oxygen and nitrogen are in situ doped in the APCNs. Activation is also effective, and the SSA of APCNs reaches a maximum value of 1575 m2/g at a KOH ratio of 2:1. The solvent-based synthesis is unique and competitive in terms of high efficiency and energy conservation. [Display omitted] • A novel liquid-phase method for preparing amorphous porous carbon nanoparticles is developed based on an oxidation mechanism. • The synthesis is carried out at ambient atmosphere at 180 °C. • The specific surface area and pore volume are 936.11 m2/g and 1.45 cm3/g, respectively. [ABSTRACT FROM AUTHOR]

N,N-Dimethylformamide (DMF) and N-methylpyrrolidinone (NMP) are two of the common organic solvents which are facing increasing restrictions in terms of chemical safety and environmental regulations. Thus, seeking greener alternatives to replace them becomes an urgent need. Cyrene™ has recently evolved as one of the greener alternatives in many applications. However, its high viscosity greatly limits its broader applications. In this study, a series of Cyrene™ blends, a solvent system created by blending Cyrene™ with other common organic solvents, were developed and studied to address the Cyrene™'s viscosity issue. The material stability and applications in organic syntheses, i.e. HATU amide coupling, Suzuki coupling, Sonogashira coupling, N-alkylation, SNAr reaction, aldimine reaction and 2-pyridyl homocoupling, are also investigated to demonstrate the usefulness of these Cyrene™ blends. [ABSTRACT FROM AUTHOR]

Dihydrolevoclucosenone (Cyrene is its market name) is a biomass-derived solvent that can be produced in only two steps from biomass, while being biodegradable, non-mutagenic and non-toxic. Its "green" profile combined with its physical properties makes Cyrene a plausible substitute for a number of widely used toxic organic solvents. The first attempt to assess Cyrene as a solvent dates back to 2014 and since then, numerous research groups have opted for this promising alternative. Cyrene has successfully been employed as a solvent in materials chemistry, peptide chemistry, organic synthesis and many more research fields, which are going to be discussed in the context of this review. [ABSTRACT FROM AUTHOR]

Aromatic carboxylic acids are prone to decarboxylate in high-temperature water (HTW). While the decarboxylation kinetics of several aromatic carboxylic acids have been explored, studies on their compatibility with organic syntheses in HTW are scarce. Herein, we report the hydrothermal synthesis (HTS) of 2,3-diarylquinoxaline carboxylic acids from 1,2-diarylketones and 3,4-diaminobenzoic acid. A detailed study of the reaction parameters was performed to identify reaction conditions towards minimal decarboxylation. Thirteen 2,3-diarylquinoxaline-6-carboxylic acids are obtained at temperatures between 150–230 °C within 5–30 minutes. The reported conditions feature comparable performance to those of classic syntheses, avoiding volatile organic solvents, strong acids and toxic catalysts. Decarboxylated quinoxalines arise as side products in variable amounts via direct decarboxylation of the 3,4-diaminobenzoic acid. To completely inhibit the decarboxylation, we show that suitable structural analogues of 3,4-diaminobenzoic acid can act as starting compounds. Thus, ester hydrolysis of methyl 3,4-diaminobenzoate and deprotection of di-Boc-protected 3,4-diminobenzoic can be coupled with the HTS of quinoxaline towards quinoxaline carboxylic acids, while fully avoiding decarboxylated side products. [ABSTRACT FROM AUTHOR]

Herein, we report the feasible synthesis of a series of porous organic cages (POCs, e.g., CC1, CC2, CC4, and CC3–OH) through a straightforward and effective dynamic solvent-mediated strategy. Notably, the preparation of POC nanocrystals can be significantly shortened from days/weeks (by traditional methods) to just 4 h, even at a large scale (around 2 g), due to the accelerated imine-bond formation. The easy-purification of POCs involving a filtration procedure also enables good solvent recyclability, which has been seldomly discussed in previous reports, but may be promising in potential industrial production. Moreover, the solvent media induce increased disorder of cage molecules within the nanocrystals, imparting expanded porosity with enhanced gas sorption property. Our finding may provide a universal tool for the synthesis and utilization of certain imine-based POCs, potentially advancing this field. The dynamic solvent-mediated strategy is developed for the rapid and scalable synthesis of porous organic cages with solvent recyclability. [Display omitted] • The preparation of porous organic cages could be significantly shortened from days/weeks to 4 h with synthetic scalability. • The purification is simple that endows a good solvent recyclability. • The porosity could be enhanced with promoted gas uptake capabilities due to the disorder of cage arrangement. [ABSTRACT FROM AUTHOR]

In the past decades, photocatalytic and photoelectrocatalytic methods have been widely employed for the degradation of harmful compounds present both is gaseous and aqueous effluents. In the last years scientists have paid great attention to the synthesis of valuable compounds and hydrogen production. Organic syntheses are generally carried out in organic solvents, under high temperature/pressure, with toxic oxidants such as permanganate. On the other hand, photocatalysis and photoelectrocatalysis using water as solvent, air or water as oxidant, and sunlight as energy source, can be an efficient alternative to the traditional, non-environmentally friendly methods. This review summarizes the photocatalytic and photoelectrocatalytic transformations of organic molecules to commercially valuable products in water, sometimes evaluating also the contemporary H 2 production. The reaction conditions, mechanisms and kinetics are presented and discussed. Future perspectives are also given. [Display omitted] • Photocatalytic and photoelectrocatalytic synthesis of high added value compounds. • Photocatalytic and photoelectrocatalytic partial oxidation in aqueous medium. • Overview on the use of new photo(electro)catalytic systems. • Synergistic effect between photo- and electro-catalysis. [ABSTRACT FROM AUTHOR]

Dimethyl sulfoxide (DMSO) is a cheap polar aprotic solvent used in organic synthesis and in pharmacology because of its low cost, high stability, and non-toxicity. Multicomponent reactions (MCRs) are highly convergent processes and have good atom, step, and pot economies. In this communication, the multicomponent transformation of salicylaldehyde, malononitrile dimer, and nitromethane in DMSO at room temperature was investigated to give 2,4-diamino-5-(nitromethyl)-5H-chromeno[2,3-b]pyridine-3-carbonitrile in good yield. The structure of the earlier unknown compound was confirmed by means of elemental analysis, mass-, nuclear magnetic resonance, and infrared spectroscopy. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) is generally prepared in a water medium. However, a new method for the synthesis of PANI in an organic solvent was developed in this study. PANI was successfully synthesized in an organic cholesteric liquid crystal (CLC) matrix using ammonium peroxodisulfate and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) as two initiators to progress the polymerization. Polymerization in the CLC matrix resulted to PANI with an ordered structure due to secondary doping in the monomer propagation process. [ABSTRACT FROM AUTHOR]

Transition metal mediated C–H functionalization has been highly relevant in organic synthesis for decades. However, sustainability as an inherent feature in such transformations remains under-developed. Through a varied approach, we have explored metal-centered catalysis practiced via mechanochemistry and under microwave-irradiation, both strictly without the use of any toxic organic solvents. In some sections of this report, we shed light upon C–H functionalizations carried out in the universal and clean solvent water, as well as in neat, solvent-devoid conditions. Different metal centers like Pd, Rh, Ru, Cu, Fe, Co and a spectrum of mechanistic pathways that have accomplished these reactions in an unconventional but green protocol, are discussed extensively. This serves as an attempt to address the challenges in environmental preservation while carrying out organic reactions, and to encourage innovative versatile ideas. Our review collectively presents the endeavours that have introduced hazard-free methodologies in these C–H activation pathways. [ABSTRACT FROM AUTHOR]

Dimethyl sulfoxide (DMSO) is widely used as a solvent in organic synthesis and in pharmacology because of its low cost, stability, and non-toxicity. Multicomponent reactions are a powerful synthetic tool for the rapid and efficient construction of complicated molecular frameworks. In this communication, the multicomponent transformation of salicylaldehyde, malononitrile dimer, and dimethyl malonate in DMSO at room temperature was carefully investigated to give dimethyl 2-(2,4-diamino-3-cyano-5H-chromeno[2,3-b]pyridin-5-yl)malonate with good yield. The structure of the new compound was established by means of elemental analysis and mass, nuclear magnetic resonance, and infrared spectroscopy. [ABSTRACT FROM AUTHOR]

Green chemistry is the basis for fast‐growing, eco‐friendly, alternative sustainable technologies for the development of chemical products without the use or generation of hazardous catalysts. The role of naturally occurring fruit juice as a catalyst or solvent in organic synthesis has gained focused interest across the globe. Lemon juice‐mediated synthesis has been widely explored recently as a highly significant, selective solvent and biocatalyst in organic synthesis. This review presents recent developments on lemon‐juice mediated transformations and their application to synthesize molecules or building blocks of pharmaceutical interest. We believe this review article will be of interest to researchers both in academic and industrial settings focused on developing novel pharmacophores from a green chemistry principles perspective. [ABSTRACT FROM AUTHOR]

Bacterial tyrosinases, as in the case of other bacterial oxidative enzymes, have been found to possess biochemical characteristics that typically make them more suited to applications requiring special operational conditions such as alkaline pH, high or low temperature, the presence of organic solvents, and the presence of inhibitors. Even though a great deal is known about fungal tyrosinases, bacterial tyrosinases still vastly remain underexplored for their potential application in organic synthesis. A literature survey in particular highlights the gaps in our knowledge pertaining to their biochemical properties. Bacterial tyrosinases have not only shown promise in the synthesis of medically important compounds such as L-3,4-dihydroxyphenylalanine (L-DOPA) and melanin but have also seen application in cross-linking reactions of proteins and the polymerization of environmental pollutants. Their ability to catalyse o-hydroxylation reactions have shown some degree of promise in the biocatalytic conversion of resveratrol to piceatannol, tyrosol to hydroxytyrosol, and many more. In this review, we will explore the world of bacterial tyrosinases, their current applications, and future perspectives for the application of these enzymes in organic synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] Bottom-up synthesis of cubosomes is more energetically favourable than top-down approaches. However, bottom-up methods often rely on organic solvents such as ethanol as diluents, and lead to concurrent formation of liposomes. We propose using non-toxic diluents such as honey, glycerol and lactic acid for bottom-up cubosome synthesis. Cubosomes were prepared using solutions of phytantriol in a range of diluents including choline chloride-glycerol, honey, lactic acid, glycerol, and ethanol. These solutions were added dropwise to water containing the stabiliser, poloxamer 407, following an established method of cubosome synthesis. The resulting structures were characterised using small-angle X-ray scattering, DLS and cryo-TEM. Cubosomes were successfully formed using a range of non-toxic diluents. This demonstrates that harmful organic solvents like ethanol are not required, and that the diluents need not be hydrotropes. Furthermore, unlike ethanol, these other diluents allowed formation of cubosomes without concurrent formation of liposomes. Given the huge potential for cubosomes in drug delivery, this new method offers a potentially useful low-cost, low-toxicity synthesis option. [ABSTRACT FROM AUTHOR]

Imines are important intermediates in drug synthesis. Photocatalytic aerobic oxidative coupling of amines has been considered as a clean and promising way to produce imines and has attracted great attention. Herein, we designed and synthesized a novel two‐dimensional porphyrin‐based covalent organic framework (Por‐BC‐COF) which adopts an AA stacking mode with excellent crystallinity, high Brunauer–Emmett–Teller surface areas (1200 m2 g−1), wide light absorption range (200–1300 nm) and good stability in a variety of organic solvents. Por‐BC‐COF can be used as a metal‐free heterogeneous photocatalyst for the photocatalytic oxidation of amines to imines under visible light and red light with a high yield (97 %). This work presents a novel and efficient COF photocatalyst in the application of light‐driven organic synthesis. [ABSTRACT FROM AUTHOR]

Molecular iodine contributes significantly to organic transformations in synthetic organic chemistry. It works effectively due to its mild Lewis acidic character, ability as an oxidizing agent, good moisture stability, and easy availability. It is non-toxic, cost-effective, non-metallic, environmentally benign, and has operational simplicity making it more popular for organic synthesis. In addition, many organic reactions show excellent stereo- and regio-selectivities within a short reaction time in common organic solvents. Previously, we reported the organic transformations catalyzed by molecular iodine up to 2012. In the present review article, we wish to highlight the significant and stringent achievements in molecular iodine catalyzed/promoted reactions from 2013 and onwards for researchers of chemistry, primarily during the last five years. [ABSTRACT FROM AUTHOR]

In the last twenty years, N‐heterocyclic carbenes (NHCs) have been extensively studied for their application as organocatalysts in stereoselective synthesis as well as ligands for transition metals‐promoted synthetic methodologies. Derived mainly from azolium salts, NHCs have demonstrated exceptional versatility in their generation usually performed by deprotonation or reduction (chemical or electrochemical). In particular, the generation of NHC under electrochemical conditions, starting from azolium‐based ionic liquids, has proven to be a successful green approach and demonstrated wide applicability in organic synthesis. In this Personal Account, the application of electrogenerated NHCs in organic synthesis will be discussed, with a particular attention to the different reactivity in ionic liquids compared to classical organic solvents. [ABSTRACT FROM AUTHOR]

Selenium-catalysed oxidations are highly sought after in organic synthesis and biology. Herein, we report our studies on the on water selenium mediated oxidation of anilines. In the presence of diphenyl diselenide or benzeneseleninic acid, anilines react with hydrogen peroxide, providing direct and selective access to nitroarenes. On the other hand, the use of selenium dioxide or sodium selenite leads to azoxyarenes. Careful mechanistic analysis and 77Se NMR studies revealed that only Se(IV) species, such as benzeneperoxyseleninic acid, are the active oxidants involved in the catalytic cycle operating in water and leading to nitroarenes. While other selenium-catalysed oxidations occurring in organic solvents have been recently demonstrated to proceed through Se(VI) key intermediates, the on water oxidation of anilines to nitroarenes does not. These findings shed new light on the multifaceted nature of organoselenium-catalysed transformations and open new directions to exploit selenium-based catalysis. [ABSTRACT FROM AUTHOR]

The production of fluorescent polymer dots (PDs) from biomass compounds usually requires additional toxic reagents or external energy input, due to which the facile and green fabrication strategies are still highly desirable. Herein, we report the general and modular preparation of natural polyphenol-based fluorescent PDs via a one-pot co-polymerization reaction under a mild condition. The use of natural polyphenols as the starting materials has completely prevented the use of organic solvents and harsh chemicals, whereas the high reactivity of natural polyphenols allowed the facile and modular fabrication of fluorescent PDs without any external energy input and sophisticated organic synthesis. The luminescence properties of the resulting PDs were dependent on the structure of natural polyphenols, and it was found that PDs possessed good photostability and biocompatibility. In addition, PDs showed high selectivity towards copper ions among cations, anions, and biomolecules, which were further employed to detect copper ions in living cells and environmental water samples. Thus, this strategy offers a green and facile route for the design and preparation of natural molecule-based PDs for biomedical and environmental applications. [ABSTRACT FROM AUTHOR]

Microemulsions are clear, stable, isotropic mixtures of oil, water, and surfactant, frequently in combination with a cosurfactant. These systems are currently of interest to the pharmaceutical scientist because of their considerable potential to act as drug delivery vehicles by incorporating a wide range of drug molecules. The purpose of this work is to solubilize in AOT [sodium bis(2‐ethylhexyl)sulphosuccinate] water‐in‐oil microemulsions at two different R‐values the Chromobacterium viscosum (CV) lipase and lipoprotein lipase ex Pseudomonas and to use them to catalyze the lactonization of 16‐hydroxyhexadecanoic acid at 40°C. CV lipase is also immobilized in gelatin‐containing microemulsion‐based gels (MBGs) with retention of catalytic activity. These lipase‐containing MBGs proved to be novel solid‐phase catalysts for use in apolar organic solvents. CV lipase‐containing MBGs are used to synthesize, on a preparative scale, a variety of different esters under mild conditions. [ABSTRACT FROM AUTHOR]

Reducing or eliminating organic solvent use in pharmaceutical manufacturing is perhaps the most effective way to reduce the environmental, health, and safety impacts of drug substance manufacturing. With this in mind, we have developed a process to manufacture an investigational 5-HT4 receptor agonist that is conducted almost entirely in water, including multiple controlled isolations. Key transformations carried out in aqueous media include a benzimidazole cyclization, amide bond formation, reductive amination, and a selective oxidation of an aliphatic alcohol. Compared to the first-generation manufacturing process using organic solvents, the aqueous process described here uses 77% less material inputs, 94% less organic solvent, and, surprisingly, 48% less water, while improving overall yield from 35% to 56%. [ABSTRACT FROM AUTHOR]

Front Cover: FeIII-Based Eutectic Mixtures as Multi-task and Reusable Reaction Media for Efficient and Selective Conversion of Alkynes into Carbonyl Compounds (Chem. Eur. J. 57/2023) Keywords: alkynes; atom economy; deep eutectic solvents; FeCl3-mediated organic synthesis; hydration EN alkynes atom economy deep eutectic solvents FeCl3-mediated organic synthesis hydration 1 1 1 10/18/23 20231013 NES 231013 B Thanks to the use b of a sustainable Fe SP III sp -based deep eutectic solvent ( I DES i ) as promoter/reaction medium, alkynes were hydrated under bench-type reaction conditions (45 °C, air, absence of co-catalysts or co-solvents). Alkynes, atom economy, deep eutectic solvents, FeCl3-mediated organic synthesis, hydration. [Extracted from the article]

Adaptation of all‐in‐one ionic systems with ionic liquids (ILs) serving as solvent, reactant, and catalyst is an innovative approach in the organic synthesis. Mild and bio clean choline based ILs as all‐in‐one systems (solvent, reagent, and catalyst) were developed via a simple metathesis approach and were applied on the ring‐opening reaction of epoxides. Sustained transformation of various epoxides using choline cyanide, azide, and hydroxide ILs delivered a neat, efficient and convenient protocol for the synthesis of β‐substituted alcohols in moderate to high yields (64‐97 %) with excellent activity and selectivity as confirmed by nuclear magnetic resonance (NMR) spectroscopic data. [ABSTRACT FROM AUTHOR]

In these environmentally conscious days there is need to use eco‐friendly greener technologies, such as solvent free, microwave, ultrasound and use of room temperature. Here report an efficient and green protocol for the synthesis of 5‐aminopyrazole‐4‐carbonitrile from three component condensation of phenyl hydrazine, aldehyde, and malononitrile using NaPTS as catalyst in aqueous medium. Use of water has emerged as a versatile solvent for organic reaction; it is readily available, inexpensive, environmentally benign, neutral and natural solvent. Multicomponent reactions in water are of outstanding value in organic synthesis and green chemistry. The significant features of this article are short reaction time, provide excellent yield, removal of toxic solvent and use of water as green solvent. [ABSTRACT FROM AUTHOR]

Cinnamyl acetate has a wide application in food industries. This work focuses on cinnamyl acetate synthesis with a novel esterase. estGUZ753, an esterase gene from Geobacillus uzenensis DSMZ 13551, was first cloned and expressed in Pichia pastoris KM71. The optimal activity of EstGUZ753 towards p-NP caprylate was at pH 8.0 and 70 °C, and the half-life at 70 °C was 28 h. Furthermore, EstGUZ753 showed marked tolerance in methanol. The activity of EstGUZ753 increased up to 1.16-fold in 90% methanol after 72 h, and the half-life in it was 336 h. The crude fermentation broth of EstGUZ753 was immobilized directly onto the epoxy resin (Lx-105s), and the immobilized EstGUZ753 exhibited a 99% conversion for cinnamyl acetate synthesis at a high cinnamyl alcohol concentration in 6 h (cinnamyl alcohol: 1.0 M, enzyme dosage: 3%). These characteristics of EstGUZ753 indicated its great potential for organic synthesis. A novel esterase gene from Geobacillus uzenensis DSMZ 13551 was first cloned and expressed in Pichia pastoris KM71. Esterase EstGUZ753 showed marked thermostability at high temperature and tolerance in methanol. Furthermore, the crude fermentation broth of EstGUZ753 was immobilized directly onto the epoxy resin, and immobilized EstGUZ753 exhibited a 99% conversion for cinnamyl acetate synthesis. [ABSTRACT FROM AUTHOR]

Designing reactions in aqueous media has been one of the major challenges in modern organic synthesis, especially to avoid the use of large amounts of organic solvents whose disposal is a matter of grave concern from an environmental perspective. The oxidation of alcohols and amines is an essential and important step in the synthesis of many valuable products including polymers and pharmaceuticals. In recent times, there has been a surge in the use of water as a solvent in many organic reactions. This review focuses specifically on the oxidation reactions of alcohols and amines carried out in water media using transition metal catalysts, metal‐free catalysts and photocatalysts. [ABSTRACT FROM AUTHOR]

Biocatalysis has emerged as an important tool in synthetic organic chemistry enabling the chemical industry to execute reactions with high regio- or enantioselectivity and under usually mild reaction conditions while avoiding toxic waste. Target substrates and products of reactions catalyzed by carboxylic ester hydrolases are often poorly water-soluble and require organic solvents, enzymes are evolved by nature to be active in cells, i.e. in aqueous rather than organic solvents. Therefore, biocatalysts withstanding organic solvents are urgently needed. Current strategies to identify such enzymes rely on laborious tests carried out by incubation in different organic solvents and determination of residual activities. Here, we describe a simple assay useful to screen large libraries of carboxylic ester hydrolases for resistance and activity in water miscible organic solvents. We have screened a set of 26 enzymes, most of them identified in this study, with four different water miscible organic solvents. The triglyceride tributyrin was used as a substrate and fatty acids released by enzymatic hydrolysis were detected by a pH shift indicated by the indicator dye nitrazine yellow. With this strategy, we succeeded to identify a novel highly organic solvent tolerant esterase from Pseudomonas aestusnigri. In addition, the newly identified enzymes were tested with sterically demanding substrates, as common in pharmaceutical intermediates, and two enzymes from Alcanivorax borkumensis were identified which outcompeted the gold standard ester hydrolase CalB from Candida antarctica. [ABSTRACT FROM AUTHOR]

The main objective of this study was to replace the traditionally applicable volatile organic solvents and imidazolium‐based ionic liquid solvents with thermally stable surfactant, cetylpyridinium bromide as surfactant ionic liquid (SIL) and examine the potential of the same as viable reaction medium in the synthesis of stilbenes, quinoxaline and pyridone decorated substrates via Heck cross‐coupling reaction. This work thoroughly investigates the thermal, spectral and morphological properties of cetylpyridinium bromide as surfactant ionic liquid. Cetylpyridinium bromide is a well‐known germicide with well‐established degradation mechanism and displays remarkable solvent properties for the homogeneously catalysed Heck cross‐coupling reactions, which is of great significance to enlarge the applications window of cetylpyridinium bromide from biologically significant surfactant material to the choice of solvent in synthetic organic chemistry. [ABSTRACT FROM AUTHOR]

A series of 8‐azacoumarin, naphthyridine, and dioxazphenalene derivatives bearing conjugated moieties were intended and prepared by a concise and smooth approach using grinding and ultrasonic irradiation. A sustainable one pot reactions have emerged and progressed smoothly as an efficient and eco‐safe methods in solvent less organic synthesis. The desired products were obtained in high yields, and the structures of all products were established on the basis of spectroscopic data and elemental analysis. Using the density functional theory (DFT) realized the electronic and structure characterization of synthesized azacoumarin. These heterocyclic compounds are chemically stable and are tested as antioxidants. Antioxidant potential was assessed using ABTS, and anti‐hemolytic activity was evaluated by induced peroxide hemolysis. They gave good antioxidant results that showed potency ranging from good azacoumarin analogues 8, 9, 13, 17, and 20, among compounds, showed much potency than that of commercial ascorbic acid. [ABSTRACT FROM AUTHOR]

In recent years, there has been an increasing tendency to use biocatalysts in industrial chemistry, especially in the pharma and fine chemical sector. Preferably, enzymes or whole cells, applied as catalysts for a specific biotransformation, are utilized in aqueous reaction media since water is the natural medium for enzymes. In numerous examples of biocatalytic systems, however, a major problem is the insolubility of hydrophobic substrates in such aqueous reaction media. Apart from lipases, many enzymes are highly sensitive to organic solvents and are inactivated by an organic medium. Therefore, a change of solvent for biotransformations from water to organic solvents is usually challenging. In this study, we investigated the synthesis of nitriles by an organic solvent‐labile aldoxime dehydratase in pure organic solvents, exemplified for the dehydration of n‐octanaloxime to n‐octanenitrile. We present a method for applications in batch as well as flow mode based on an "immobilized aqueous phase" bearing the whole cells in a superabsorber as solid phase, thus enabling the use of a purely organic solvent as "mobile phase" and reaction medium. [ABSTRACT FROM AUTHOR]

Here we report for the first-time various organic transformations such as aldol condensation, oxidation, nucleophilic substitutions, protection, acylations and coupling reactions using a mechanochemical approach at a controlled temperature using a single synthesis platform. Almost minimal solvents or solvent-free conditions are used, making it a very efficient and clean synthesis of various products. A jacketed screw reactor when operated at different temperatures (0 °C to 160 °C) and over a range of rotation speeds for changing the residence time (15 s–300 s) helped to achieve maximum conversion. This approach is also extended to the synthesis using substrates having different substitutions, heterocycles and steric hindrance. [ABSTRACT FROM AUTHOR]

A prototypical porous organic cage denoted as CC3 was synthesized in the presence of dimethylformamide as solvent. Stirring effects and solvothermal treatment conditions lead to distinctive morphological, structural, and textural properties of the resultant CC3 crystals. The presence of DMF led to a mixture of alpha and dissymmetric cage structures. The crystallinity of the resulting crystals was highly dependent on the solvothermal temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Facile synthesis of a new bio-based polar aprotic solvent. • The key physical properties and stability were investigated. • Excellent green solvent for the Suzuki and Sonogashira reactions. • Suitable for thiourea organocatalyst syntheses and asymmetric Michael additions. • Promising green solvent for the depolymerization of BPA–PC and PET. Applications of polar aprotic solvents are inevitable in the chemical industry, but few nonhazardous alternatives are available. Herein, we propose methyl sesamol (MeSesamol) as a promising new bio-based alternative for polar aprotic solvents and demonstrate its versatile applications. MeSesamol was derived from natural resources using environmentally friendly and facile procedures, such as methylation using dimethyl carbonate. MeSesamol has a distinctive smell and demonstrates excellent properties as a green solvent candidate: high boiling and open-cup flash points, immiscibility with water but miscibility with common organic solvents, high stability and resistance to several acids and bases. MeSesamol was an effective solvent in nine C–C coupling reactions, including the Suzuki and Sonogashira reactions and asymmetric Michael addition. MeSesamol lies close to dichloromethane (DCM) in Hansen space and achieves a similar or higher yield and enantiomeric excess (up to 97% and 99%, respectively) in the asymmetric Michael reactions compared to DCM. MeSesamol proved to be an excellent recyclable solvent in the depolymerizations of bisphenol-A polycarbonate (BPA–PC) and polyethylene terephthalate (PET). MeSesamol was recycled in five reaction cycles with excellent efficiency (92%–100%) and outstanding cumulative monomer yields (92% bisphenol-A from BPA–PC and 92% terephthalic acid from PET). To properly compare the depolymerization reactions, we propose two green metrics, namely, the corrected energy-economy factor (ε corr) and the corrected environmental energy impact (ξ corr). [ABSTRACT FROM AUTHOR]

In the last decades, cross-coupling approaches have been widely used to generate structural diversity efficiently. Among various transition-metals, palladium has remained the most understood metal to efficiently catalyze cross-couplings. The introduction of sustainability parameters, such as atom-economy, process mass intensity (PMI), or E-factor highlighted the fundamental inefficiencies associated with the traditional practices in organic synthesis. Critical analysis in the context of these factors identified organic solvents as the major culprit. In this scenario, employing water as a bulk reaction medium for cross-couplings has emerged as an attractive alternative. Fine-tuning the solvation features of water by adding non-ionic surfactant provides an exciting opportunity to practice sustainable organic synthesis. This approach has gained substantial attention in the last ten years and established a basic framework for practicing organic chemistry under aqueous conditions, ultimately reducing the reliance on toxic organic solvents. In this review, along with the future directions and challenges, recent advances in the field of micellar catalysis applied to palladium mediated cross-couplings will be discussed. [ABSTRACT FROM AUTHOR]