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Experiments were conducted to study the effects of reaction conditions on the hydrolysis of miscanthus dissolved in 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) catalyzed by H2SO4. It was determined that while there is a small co-inhibition effect associated with the simultaneous hydrolysis of the cellulosic and hemicellulosic portions of miscanthus, the largest rate decreases were observed for the hydrolysis of the hemicellulosic portion. This rate decrease was attributed to the chemical linkage between hemicellulose and lignin in miscanthus, which could be broken with chemical pretreatment. While chemical pretreatment increased the rate of the hydrolysis of the hemicellulosic component, delignification showed no further benefit. The rate of hydrolysis was determined to be first order in concentrations of β-1,4 glycosidic linkage and acid, and zero order in water concentration. The activation energy for the hydrolysis of the glycosidic linkages in the cellulosic and hemicellulosic components were determined to be 95 kJ mol−1and 114 kJ mol−1respectively. Progressive addition of water during the first hour of the reaction increased conversion and selectivity to saccharine products, while limiting dehydration of the sugars formed. The conversion of the cellulosic portion of miscanthus could be increased after the first hour of the reaction by increasing the reactor temperature. While miscanthus is only partially soluble in [Emim][Cl], it was found that the initial miscanthus loading could be increased to 9 wt% before significant yield decreases attributed to solubility limitations of the cellulosic component were observed. By proper adjustment of reaction conditions, it was possible to achieve yields of sugars approaching 84% from the cellulosic and hemicellulosic components of miscanthus, with minimal dehydration of the sugars to furans. [ABSTRACT FROM AUTHOR]

The ruthenium catalysed cross-metathesis of terpenoids with methyl acrylate and methyl methacrylate was used to prepare new terpenoids and to improve, to a large extent, the synthesis of known terpenoids. In particular, the cross-metathesis of mono-unsaturated terpenoids was very efficient whereas the transformation of terpenoids incorporating two double bonds was more difficult due to side reactions. The cross-metathesis reactions were carried out under environmentally friendly conditions either in dimethyl carbonate or under solvent-free conditions. [ABSTRACT FROM AUTHOR]

The immobilization of N-sulfonyl-(Ra)-binam-d-prolinamide using polystyrene as a support allows the recovery of an efficient catalytic system for the enantioselective direct aldol reaction between different ketones and aldehydes under solvent-free or aqueous conditions. The polystyrene-supported N-sulfonyl-(Ra)-binam-d-prolinamide catalyst in combination with benzoic acid showed similar results to those obtained with unsupported N-tosyl-binam-derived prolinamide under similar reaction conditions. The aldol products were obtained at room temperature and using only 2 equivalents of the ketone with high yields, regio-, diastereo- and enantioselectivities. The aldol reaction between aldehydes can also be performed under these reaction conditions with moderate results. The recovered catalyst can be reused up to six times without having a detrimental effect on the achieved results. [ABSTRACT FROM AUTHOR]

The biological synthesis of metal nanoparticles from ions has recently emerged as a novel technique for an environmentally benign recovery of heavy metals. Bacteria are known to recover palladium(0) in the form of nanoparticles that are catalytically active. However, the extent of the reactions that can be catalysed by bio-recovered palladium has not been investigated. This study demonstrates that the Suzuki–Miyaura and Mizoroki–Heck reactions can be catalysed by bio-generated palladium nanoparticles formed on the surface of Gram-negative bacteria. The results suggest that the range of applications of this catalyst can be extended to the realm of carbon–carbon bond formation in synthetic organic chemistry. [ABSTRACT FROM AUTHOR]

The present paper reviews 47 Life Cycle Assessments (LCA) applied to chemical reactions. The selection of the evaluated articles was conducted with a systematic literature review methodology. The review arises from the need to define the best methods for developing LCAs of chemical processes at industrial scale. The authors go through the stages defined in ISO 14040 and 14044, identifying both the gaps and the best techniques used in all the reviewed papers. The main difficulty observed when developing LCAs of chemical reactions is the lack of data due to confidentiality issues in chemical companies. In addition, this data is commonly only available at the laboratory scale. Laboratory data is sometimes directly upscaled without further consideration. Even though, simulation software, advanced calculations benchmarks, pinch analysis and retrosynthetic analysis are the best methods to estimate and scale up the mass and energy balances in the Life Cycle Inventory (LCI) stage. The article discusses these upscale procedures, makes a deep analysis of each single LCA stage, and assesses how chemical process information is managed, which is a novelty regarding previous reviews of chemical reaction LCA. From the Life Cycle Impact Assessment (LCIA) methodologies, they should be standardized to enable the comparability between LCAs of the same product. Both the European Commission and the Life Cycle Initiative are making progress in this regard. Eventually, the ReCiPe is the most used methodology among the reviewed papers. Finally, the article proposes different analyses to be performed in the interpretation phase: i.e., projecting the energy mix foreseen for the years 2030 and 2050 in energy-intensive processes or including other sustainability vectors (economic and social) in cross-cutting projects. [ABSTRACT FROM AUTHOR]

Fungi are a diverse group of organisms that play an essential role in the biosphere. They have a unique ability to produce a vast array of secondary metabolites, including enzymes that have important applications in various industries. Fungal enzymes have been utilized in many fields, such as food processing, textile, paper, and pulp industries, to name a few. In recent years, there has been growing interest in the use of fungal enzymes in the synthesis of pharmaceutical compounds due to their scalability, high catalytic activity, relatively low cost, and ability to catalyze a wide range of chemical reactions under mild reaction conditions making the overall process greener and sustainable. Fungi produce a variety of enzymes such as oxidoreductases, transferases, and hydrolases which can be used in the synthesis of specific compounds with required chemo-, regio-, and stereoselectivity. This paper discusses the role of fungal enzymes in the synthesis of various drugs, active pharmaceutical ingredients (API), and drug intermediates and their applications in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Single-electron reduction of a carbonyl by photoredox catalysis enables the generation of ketyl radicals, providing a benign procedure for constructing C–C bonds. However, external photocatalysts are required. In this paper, photoinduced generation of ketyl radicals and application in C–C coupling are reported, which require no use of any external photocatalyst. Irradiation of carbonyl with purple light in the presence of a tertiary amine generates highly reactive ketyl radicals, enabling a series of important reactions in synthetic chemistry, such as the reductive coupling of aldehydes, ketones, and imines, the allylation of aldehydes, the Barbier reaction, reductive arylation, and aldehyde–aniline coupling. We also present evidence to support the ketyl radicals being formed via photoinduced intermolecular electron transfer from the tertiary amine to aryl aldehydes. [ABSTRACT FROM AUTHOR]

In view of the growing demand for synthetic molecules or materials by researchers from both the core sciences and interdisciplinary sectors, the field of organic synthesis needs to be strategically more powerful to produce more molecules in a shorter time. Ensuring a reduction in the use of solvents, catalysts, reagents, time, effort, and waste is essential during green chemical syntheses. Keeping those criteria in mind, the integration of chemical reactions is very much needed. Integrated organic synthesis can be considered the ideal replacement for stepwise synthesis to fulfill demand while maintaining green parameters. The electrochemical cascade process satisfies the essential criteria of greener integrated synthesis to a great extent, providing a modern strategic tool in the arsenal of synthetic chemists. The strategy is applied extensively by researchers, as evidenced by the growing number of publications, amounting to more than a hundred papers on the development of synthesis methods using electrochemical cascade reactions. A thorough understanding of the process is needed to implement the strategy further in targeted synthesis and methodology development for cutting-edge research. To grow the concept among researchers, a concise account of published articles on the topic, depicting the mechanisms, prospects, and problems of the developed methods, is highly desirable. Quenching the thirst herein, we present a concise review of electrochemical cascade processes reported in the literature since 2015. The precedent reactions developed earlier are also discussed in this context. Electrochemical multicomponent reactions involving the cascade process are also covered, expanding the scope of the review. The sections are classified based on the types of functionalization. The mechanistic details of each category of reactions are thoroughly covered to present a clear idea of the redox behavior of different reagents under electrochemical conditions. The prospects and problems associated with the methods are also discussed. [ABSTRACT FROM AUTHOR]

This work evaluates sustainability indicators of the biorecovery of platinum group metals (PGM) from spent automotive catalysts (SAC) with due consideration of the environment and efficiency and forms the basis for the evaluation of environmental sustainability. Green chemistry metrics have been quantified for all the processes involved in the bioextraction of PGM from SAC under different experimental conditions. Three different cyanogenic (hydrogen cyanide forming-HCN) bacteria namely Pseudomonas fluorescens, Bacillus megaterium, and Chromobacterium violaceum were used in two-step bioleaching. These bacteria produce cyanide as a secondary metabolite that forms water-soluble complexes with PGM. Bioleaching experiments were performed at different pulp densities (i.e., 0.5% w/v, 1% w/v, 2% w/v, and 4% w/v) to examine their effects on PGM extraction and green metrics. For green metrics calculations, metal and cyanide limiting reactions were performed and four different boundary conditions were defined. Boundary conditions were defined based on the limiting reactants, desired metals, and chemical reactions. Furthermore, green metrics were calculated for an individual metal (i.e., platinum, palladium, or rhodium) and for the overall bioleaching process. This is the first study that reports an in-depth analysis of the environmental sustainability of the PGM biorecovery process by quantifying the green metrics under diverse experimental conditions. [ABSTRACT FROM AUTHOR]

An efficient and mild multicomponent reaction (MCR) for the preparation of vinyl sulfone is reported, which is achieved by the hydrogenation/difunctional sulfonylation of an alkynyl ester with the corresponding N-allyl bromodifluoroacetamide, DABSO and H2O under visible light conditions without the need for any metal catalysts or additives. This transformation is the first example of a conversion using H2O as the hydrogen source to interact with DABCO to form [DABCO-H]+, which ultimately reacts with the vinyl group, with the advantage of high chemoselectivity and step economy. Notably, the method produces different sulfonylation products with the same substrate regulated by the presence or absence of H2O, which greatly reduces the cost of the chemical reaction and exhibits good functional group tolerance and substrate range. In addition, gram-scale experiments proceeded smoothly, proving the practicality of the methodology. [ABSTRACT FROM AUTHOR]

Mechanochemistry refers to a chemical reaction induced by mechanical energy involving solids. This method provides several advantages over solution-phase synthesis, such as minimizing the need for large volumes of solvents in chemical reactions and greener and more efficient synthetic solutions. In this paper we obtain, via mechanochemistry, a hybrid salt, named MEFAS, derived from two antimalarial molecules – mefloquine and artesunate. We demonstrate, using a simple experimental procedure, how the catalytic amount of liquid present during mechanochemical reactions is decisive to obtain MEFAS. Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) data indicate that liquid-assisted mechanochemical reactions are promising in the formation of the hybrid salt, which is formed via a hydrogen interaction of the carboxylate group of the artesunate molecule with the piperidine group of mefloquine. [ABSTRACT FROM AUTHOR]

Lignin is one of the most abundant biopolymers on Earth and is considered as the primary resource of aromatic compounds. Recently, lignin has attracted attention from scientists and industrialists due to its inherent potential arising from its unique structure, which leads to its possible use in many applications. Many efforts have been made to ameliorate the reactivity and compatibility of lignin in different areas. Although methods have been proposed for endowing lignin with different properties, there continues to be a considerable demand for discovering new and effective ways of unraveling the beneficial uses of this aromatic polymer. Considering the structure of lignin, different grafting modifications can occur on the aliphatic and/or aromatic groups of lignin. To date, there has been a lack of fundamental understanding of the modification pathways of lignin for generating lignin-based products. In this review paper, we discuss comprehensively the chemical reactions that were introduced in the literature for preparing lignin with different features via modifying its phenolic and aliphatic hydroxy groups for altered uses. This review paper critically and comprehensively elaborates on the recent progress in lignin reactions as well as the challenges, advantages and disadvantages associated with the reaction procedures and the product development processes. Furthermore, the research gap in reaction strategies and product development are described throughout this study. [ABSTRACT FROM AUTHOR]

Amide and peptide bonds are found in numerous natural products and biologically active compounds, including pharmaceuticals; and the formation of these bonds constitutes one of the most important reactions in organic chemistry. Herein, we report the first method for halogen-bonding-mediated formation of amide and peptide bonds, which was accomplished by using a coupling system comprising N-iodosuccinimide, 1,4-diazabicyclo[2.2.2]octane (DABCO), and an N-heterocyclic carbene precursor. The method could be used not only for synthesizing amides from carboxylic acids and amines but also for synthesizing peptides from both standard and sterically hindered amino acids in good to excellent yields without racemization. Remarkably, the coupling system allowed us to smoothly synthesize a protected form of the pentapeptide neurotransmitter Leu-enkephalin. Moreover, we also were able to use potassium persulfate, an inexpensive readily available inorganic oxidant, along with DABCO and the carbene precursor for efficient synthesis of various dipeptides. Density functional theory calculations and experimental studies showed that the bond-formation reactions involve a 2-iodobenzimidazolium intermediate that has an activated carboxyl group that forms a reactive acyloxybenzimidazolium intermediate; this intermediate is then attacked by the amino group of an amine or amino acid to afford an amide or a peptide. [ABSTRACT FROM AUTHOR]

According to the requirements of sustainable green development, the efficient green synthesis of fluorine chemical products is an inevitable trend. In this work, we used ionic liquids as an effective catalyst in an important fluorochemical reaction – hexafluoropropylene dimerization for the first time. The effects of ionic liquids with different spatial positions, substituents and nucleophilic anions on the catalytic performance of hexafluoropropylene dimerization were systematically studied. The results showed that the strong nucleophilic trisubstituted thiocyanate imidazole ionic liquid [C6mmim][SCN] had the highest activity under the optimum reaction conditions, the turnover frequency (TOF) was 108.36 h−1 and the selectivity was 97.96%. Compared with the traditional metal salt catalyst system, the catalytic activity of ionic liquids was double. In addition, based on the XPS analysis results and density functional theory (DFT), a possible reaction mechanism was proposed. The effective catalytic activity of ionic liquids was mainly attributed to the strong nucleophilicity of anions and the weak interaction between cations and anions. This work will successfully provide a green synthesis route for hexafluoropropylene dimerization and further promote the efficiency and greening of fluorine chemical reactions. [ABSTRACT FROM AUTHOR]

The engineered structures and active sites of enzyme catalysts give rise to high catalytic activity and selectivity toward desired reactions. We have employed a biomass-derived difuran compound to append N-substituted maleimides with amino acid (glutamic acid) substitution by Diels-Alder reaction to mimic the chemical functional groups that comprise the active site channels in enzyme catalysts. The difunctionality of the biomass-derived difuran allows production of Diels-Alder adducts by appending two amino acid moieties to form a difunctional organocatalyst. The catalytic activity of the organocatalyst can be improved by immobilizing the organocatalyst on solid supporting materials. Accordingly, the structures of these immobilized organocatalysts can be engineered to mimic enzymatic active sites and to control the interaction between reactants, products, and transition states of catalytic reactions. Lactose hydrolysis was carried out to provide an example of industrial application of this approach to design and fabricate new supported organocatalysts as artificial enzymes. [ABSTRACT FROM AUTHOR]

In this work, we present a comprehensive study of the electrocatalytic reduction of fructose to sorbitol and mannitol, in a mild alkaline medium (pH = 11.3), with a Cu wire as the cathode. Particular attention was paid to the reaction mechanism, investigated by linear sweep voltammetry (LSV) and chronopotentiometry (CP) coupled with high-pressure liquid chromatography (HPLC). The initial results of our study showed that at the potential where the fructose reduction reaction (FRR) is achieved, competition with the hydrogen evolution reaction (HER) tends to occur, thus limiting the Faradaic efficiency towards the FRR. Moreover, products of chemical conversions were also observed in the liquid electrolyte, originating from the isomerisation of fructose to glucose and mannose and degradation reactions (C–C breaking). Through a thorough optimisation of the reaction parameters, the Faradaic efficiency could be remarkably improved, reaching values >40% and being sustained for 10 h of electrolysis at a current of i = −20 mA. More specifically, the minimisation of the undesired chemical side reactions was achieved by the careful control of the pH (11.3 ± 0.3) using a buffer electrolyte and a titration pump, thus limiting the isomerisation of fructose to glucose and mannose to <2% in 10 h. The electrochemical conversion was optimised via a tailored strategy involving a two-step potential cycling for re-activating the electrocatalyst surface, which allowed achieving 77% electrochemical conversion of fructose to sorbitol and mannitol in 10 h of electrolysis (sorbitol : mannitol = 0.43 : 0.57). This is the first time that the electrocatalytic FRR was achieved with such a high product yield and by using a non-noble metal-based cathode, thus opening up a novel, green route for the conversion of fructose into sorbitol and mannitol. This work also provides relevant, new insight into the crucial parameters that need to be taken into account to achieve the electrocatalytic reduction of saccharides, by gaining control of their complex chemistry in solution. [ABSTRACT FROM AUTHOR]

Deconstruction of alkenes to their carbonyl derivatives is a widely used protocol in synthetic organic chemistry and several reaction conditions have been demonstrated for electron-rich and unconjugated alkenes. However, such reactions of electron-deficient and conjugated alkenes are highly challenging. In this report, we have demonstrated a light-promoted water-mediated NBS photoinitiated cleavage of electron-deficient conjugated alkenes under mild and greener conditions via the hydrogen atom transfer mechanism. Additionally, this methodology is demonstrated as a deprotection step for carbonyl groups. This protocol works at room temperature in an aqueous medium with a wide range of functional group tolerance and high regioselectivity. [ABSTRACT FROM AUTHOR]

This study sought to explore the integration of green and sustainable chemistry into the organic chemistry curriculum through a national survey of organic chemistry instructors (n = 160) within the United States. It was found that faculty were most familiar with the green chemistry topics of reaction efficiency and catalysis and least familiar with the topics of efficiency metrics and life cycle impacts of chemicals. This unfamiliarity with efficiency metrics and life cycle impacts of chemicals was echoed in a low perceived importance for chemistry and related science students to know these concepts and subsequently the incorporation of green chemistry topics was amongst the lowest of the topics evaluated. Similarly, it was found that most faculty were unaware of the United Nations Sustainable Development Goals and planetary boundaries, and thus the integration of these topics into the curriculum was also low. To identify which factors affected the integration of green chemistry, the survey items were developed using the Teacher-Centered Systemic Reform model. Stepwise linear regression was used to identify which factors significantly affected its integration into the teaching curriculum and assessments. Overall, it was found that that teacher thinking factors held the greatest impact. In addition, departmental requirement or encouragement of green chemistry integration was found to significantly impact its incorporation for both the curriculum and assessments. These results suggest that there is a need both to provide training opportunities for faculty to become more familiar with these topics and their relevance to the organic curriculum and to work with people in leadership roles at the universities to encourage departmental integration. [ABSTRACT FROM AUTHOR]

Phosphonic acids represent a class of important structural units widely found in natural products and artificially synthesized functional molecules. Nature uses β-carbonyl phosphonic acid as a versatile building block to access structurally diverse phosphonic acid derivatives, which inspires a biomimetic way for chemists, however, it is limited by the detrimental tendency of C–P bond cleavages during chemical reactions. To address this challenge, we here developed an ionic-liquid-based data-driven screening (ILDDS), an approach that can comprehensively employ multifunctional effects of ionic liquids for discovering new reactivity, developing potent synthetic reactions, and even simplifying bioactivity evaluations. Using ILDDS, we repurposed the cycloaddition of β-carbonyl phosphonate and azide to synthesize triazolyl phosphonates that usually produced phosphonate-leaving products under the traditional conditions. And then, the repurposed cycloaddition reaction allows the access of triazolyl phosphonates bearing various substituents under mild conditions. Furthermore, an integrative workflow combining modular and combinational syntheses, simple purification, and in situ bioactivity evaluation can be de novo designed and implemented in a high throughput way, finally leading to fast acquirements of phosphonate compounds for inhibiting the growth of Rhizoctonia solani. [ABSTRACT FROM AUTHOR]

Direct utilization of high-energy photons to drive chemical reactions presents a promising approach for the achievement of green reaction process. Herein, we developed a simple photochemical route that utilized 172 nm vacuum ultraviolet (VUV) photons as drivers for CO2 hydrogenation to CO and transformation of CH4 to H2 and C2H6. It was demonstrated that the reactions could proceed efficiently at catalyst-free and ambient conditions, and water could further promote the transformation of CH4. The reaction mechanism was proposed on the basis of control experiments. This study provides a green alternative to conventional catalytic processes for important reactions, i.e., CO2 hydrogenation or CH4 conversions triggered by high-energy photons under ambient conditions, which have promising potential in applications due to some obvious advantages. [ABSTRACT FROM AUTHOR]

Photo-induced transformation of soluble U(VI) to insoluble U(IV) is an effective way for uranium extraction and removal. However, the photoreduction process needs to be conducted under the protection of inert gas, hindering its practical application. In this work, we have proved that photo-induced formation of insoluble uranium peroxide mineral is an alternative approach for uranium extraction under air. Even without an external photocatalyst, the photochemical activity of the uranyl ion itself can trigger the production of H2O2 under visible light irradiation, and a chemical reaction between uranyl ions and H2O2 resulted in the formation of uranium peroxide precipitates, showing good selectivity to coexisting ions. This new strategy has great application potential in environment protection and radioactive wastewater treatment. [ABSTRACT FROM AUTHOR]

Emulsion solvents (ES), which are liquid absorbent-based CO2 capture materials, are developed as simple and expandable droplets to control CO2 capture performance. An aqueous NaOH solution, which is a chemical absorbent, is encapsulated by functionalized carbon nanotubes (CNTs) to form a solid adsorbent by enhancing the high lipophilicity and high-viscosity silicone oil. The ratio of each component controls the CO2 capture performance of the solvent. It is shown that droplets of NaOH aqueous solution formed in fine sizes improve the efficiency of the chemical reaction capacity of NaOH and CO2, and thus, even when crystallization occurs, they can be used in a stationary environment, and NaOH can be used at a high concentration. It is found that the optimum concentration of CNTs required to minimize the size of the emulsion is 0.075 wt%, while the CO2 capture capacity is 2.23 mmolCO2 g−1ES–NaOH at a pure CO2 concentration and 1.31 mmolCO2 g−1ES–NaOH at a low CO2 concentration (2000 ppm, 50% relative humidity). The oil phase can be recycled continuously by separating the crystallized aqueous phase after the CO2 capture. These results demonstrate that chemical absorbents with excellent CO2 capture performance can be used safely and for a long time in order to reduce indoor CO2, and the CO2 capture performance can be flexibly controlled. [ABSTRACT FROM AUTHOR]

Four principal intra-particle phenomena occur in a highly concerted manner during the pyrolysis of lignocellulosic materials: heat transfer, mass transfer, chemical reactions, and phase changes. Achieving a holistic understanding of these processes has been challenged by their intricate coupling, high temperatures, and rapid rates at which they occur. Heat and mass transfer have been well studied at the single-particle level but their coupling with chemical reactions and phase change within single particle models remains problematic. Equally challenging is the multiscale coupling of reactor- and single particle-scale models. Too little attention has been given to phase change. Similarly, the presence of oligomeric compounds (constituting up to 20% of the oil) has not been fully accounted for in chemical reaction schemes and physical models developed for pyrolysis. Recent studies have shown that a multiscale approach is key to predictive modelling across a variety of reactor systems. Historical and recent developments are outlined in this pyrolysis review paper regarding these four intra-particle phenomena, as well as modelling efforts to capture their effect on product yields and composition. It is critical for the design of future biomass pyrolysis systems to appropriately account for all four intra-particle phenomena and their inter-connectivities in order to predict, achieve, and maintain optimal operation. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis of γ-Fe2O3 supported Ag nanoparticles (NPs) in aqueous medium by following a green approach. The presence of Fe2O3 in the gamma phase and silver in the nanocomposite has been confirmed by Raman spectroscopy, EDAX and XPS analyses. The presence of Ag in the nanocomposite is also indicated by UV spectroscopy. In the process of in situ generation of glucose mediated Ag NPs on the γ-Fe2O3 matrix, the size of γ-Fe2O3 nanoclusters reduced from 11.6 ± 1.6 to 9 ± 1 nm as was estimated from HRTEM analysis. Glucose served as an effective stabilizer for both Ag and γ-Fe2O3 in the nanocomposite. At lower concentrations of Ag (0.15–1.2 μM) the reduction of 4-nitrophenol (4-Nip) follows pseudo-first-order kinetics and the second order rate constant for this process was found to be 5.28 × 103 dm3 mol−1 s−1. Whereas, at higher concentrations (3.2–28.9 μM), it follows zero-order kinetics and occurred with a rate constant of 1 × 10−2 mol dm−3 s−1. The amount of silver in the nanocomposite is found to influence the kinetics of the catalytic reduction in a complex scheme following the Langmuir–Hinshelwood mechanism. The recyclability of the as-synthesized nanocomposite up to 7 cycles and the catalytic effect even at a very low silver concentration (0.15 μM) associated with high surface area and superparamagnetism suggest it to be a cost effective and environmentally friendly potential catalytic system. [ABSTRACT FROM AUTHOR]

There has been a great deal of interest recently in three-dimensional (3D) graphene based materials, as they exhibit large surface areas, unique electronic properties, and other attractive features. Particularly, 3D graphene doped with heteroatoms catalysts show high electrocatalytic activity toward oxygen reduction reaction (ORR), which can be used as metal-free catalysts. Most of the existing synthesis strategies of 3D graphene invariably involve multiple steps and procedures are often energy intensive and time-consuming. In this paper, we reported a one-pot and green method to synthesize boron-doped 3D reduced graphene oxide (B-3DrGO) using the supercritical carbon dioxide (ScCO2) technique. The resulting products exhibit hierarchical porous structures, leading to a high specific surface area of 541 m2 g−1. A high content of B (2.9 at%) was detected in the product, suggesting that B-doping was efficient using this technique. The B-3DrGO displays electrocatalytic activity toward ORR, which is comparable to the commercially available Pt/C (20 wt%) catalyst, in addition to their superior durability and resistance to the crossover effect. Moreover, the supercritical fluid technique, which uses non-flammable, essentially nontoxic, inexpensive, and environmentally benign CO2, is a new and green approach for the synthesis of heteroatom doped 3D graphene. [ABSTRACT FROM AUTHOR]

Recycling retired lithium-ion batteries (LIBs) is critical for global environmental sustainability and significant to closed-loop utilization of future resources, whereas existing regeneration technologies have possessed numerous flaws, such as high chemical cost, large energy consumption, secondary pollution, and security concerns. Herein, we propose a consecutive resting-output current embedding-lithium process to recover retired LIBs. Specifically, the spent LiFePO4 (LFP) cathode materials can be directly regenerated via a widely applicable aqueous electrolysis process combined with spontaneous lithium migration, driven by concentration polarization, and targeted electrically-driven lithiation, which possesses advantages in reaction time and current utilization efficiency. Besides, lithium salts in the whole process are recyclable, and no side reaction occurs. Furthermore, detailed electrochemical kinetic analysis under different processes, tested by electrochemical impedance spectroscopy (EIS) and Tafel, illustrates that both the pre-liquid phase transfer step and electrochemical reaction process dominate the lithiation rate in the rest process, then taken over by the chemical reaction step after applying the output potential. Benchmarking analysis presents that a high current utilization efficiency (more than 90%) is maintained during output current, proving the significant economic advantages of the method, and the regenerated LiFePO4 cathode displays an excellent discharge capacity of 135.2 mA h g−1 at 1 C, with a capacity retention rate of 95.30% after 500 cycles. [ABSTRACT FROM AUTHOR]

The recycling of spent lithium-ion batteries (LIBs) is a crucial issue that has engaged extensive attention worldwide, along with the rapidly increasing usage of lithium-ion batteries. State-of-art recycling approaches, in terms of chemical leaching, have imperfections such as excessive chemical consumption, tedious recycling procedure and aggravated secondary pollution. In this research, a green and closed-loop route for the recycling of spent LiFePO4 involving oxidation leaching is demonstrated. By properly adjusting or controlling the leaching parameters, the leaching efficiency of lithium is up to 97.6% with the introduction of hydrogen peroxide, which is facilitated to achieve the transformed high-purity lithium carbonate and iron phosphate. The oxidation reaction mechanisms are clarified through thermodynamic and kinetic analyses, which identified that the oxidation leaching reaction is co-controlled by the internal diffusion and chemical reaction. Consequently, LiFePO4 cathode materials are regenerated by utilizing the obtained raw materials, as expected, which deliver superior cycling stability with less than 1% of capacity loss after 300 cycles and excellent rate performances. This research embodies the possibility of efficient recycling of LiFePO4 from spent lithium-ion batteries based on the principles of green chemistry that is possibly committed to the sustainability of the lithium-ion battery industry. [ABSTRACT FROM AUTHOR]

In recent years, photoredox chemistry has been intensively investigated due to its sustainability and low energy-cost. Here, we propose a physicochemical concept – called {2-phases 2-reactions 1-catalyst} – to perform two chemical reactions simultaneously with only one catalyst using a liquid–liquid biphasic system. The well-known and commercially available α-Keggin polyoxometalate (POM), PW12O403−, was used as a photocatalyst for oxidizing a hydrophobic compound in an organic phase. The reduced POM, PW12O404−, being more hydrophilic, diffuses then in the aqueous phase where it reduces a hydrophilic compound. After this step, the re-oxidized POM migrates back to the organic phase closing the catalytic cycle. We applied this concept to several basic reactions: oxidations of organic compounds (e.g. alcohol to aldehyde), degradation of organic dyes, metal recovery by reduction of metal ions, and in situ metal–organic complexation reactions. This concept is proposed as a powerful, simple and sustainable tool to couple diverse photo-oxidation/reduction reactions. As an example, oxidative dye degradation/metal (silver) recovery were performed using this general methodology. The main advantage of the {2-phases 2-reactions 1-catalyst} concept is the economy of one reactor and one catalyst, including its self-regeneration by another useful reaction. [ABSTRACT FROM AUTHOR]

The synthesis of chiral amines in enantioenriched form is a keystone reaction in applied chemical synthesis. There is a strong push to develop greener and more sustainable alternatives to the metal-catalysed methods currently used in the pharmaceutical, agrochemical and fine chemical industries. A biocatalytic approach using transaminase (TA or ATA) enzymes to convert prochiral ketones to chiral amines with unparalleled levels of enantioselectivity is highly appealing. However, the use of TA enzymes in synthesis is severely hampered by the unfavourable thermodynamics associated with the amine donor/acceptor equilibrium. Several 'smart' amine donors have been developed that leverage chemical and physical driving forces to overcome this challenging equilibrium. Alongside this strategy, enzyme engineering is typically required to develop TAs compatible with these non-physiological amine donors and the unnatural reaction conditions they require. We herein disclose N-phenylputrescine (NPP) as a readily accessible amine donor, inspired by the biosynthesis of the dipyrroloquinoline alkaloids. NPP is compatible with a broad range of synthetically useful TA biocatalysts and performs across an unparalleled variety of reaction conditions (pH and temperature). Synthetic applicability has been demonstrated through the synthesis of the anti-diabetic drug sitagliptin, delivering the product in excellent enantiopurity using just two equivalents of NPP. [ABSTRACT FROM AUTHOR]

Considering the increasing demand for fertilizers to support the global food supply, as well as the high-energy consumption and environmental concerns caused by industrial nitrogen fixation (i.e., Haber–Bosch process), there is a critical need to develop and integrate more sustainable, green-chemistry-based processes of nitrogen fixation. As a prominently electrified Power-to-X (where X stands for chemicals, fuels, and other high-value products) approach, non-thermal plasmas generated by the spark and gliding arc discharges are highly promising to meet the required criteria, especially when the power and the electrified chemical reactions are precisely dosed and timed using nanosecond repetitively pulsed plasmas. However, the underlying mechanism for NOx formation in plasmas is a stumbling block for further green chemistry process developments. Here, a nanosecond pulsed spark discharge based on a plate-to-plate configuration was developed for sustainable nitrogen fixation at ambient conditions. Outstanding energy efficiency of 4–11 g kW h−1 and a concentration of 960–10 900 ppm for NOx formation were obtained with the varied airflow rates ranging from 40 to 340 mL min−1. Using the optical emission spectroscopy and the chemical kinetics model, we found that the key intermediate species involved in NOx reaction pathways strongly depend on the plasma parameters and species residence time in spark discharges. It is revealed that more than 50% of the generated NO originate from the chain reactions of O and N radicals with vibrationally excited N2 and O2 molecules (O + N2(υ) → NO + N and N + O2(υ) → NO + O). Most NO2 molecules are formed by further oxidation of NO species (NO + O → NO2). The presence of O and N spectral lines at the post-discharge stage further confirmed the important role of free-radical-chain reactions. These results provide new insights into sustainable and decentralized NOx production, and deeper understanding of the plasma-based green chemistry will guide the optimization and practical applications of the plasma-based power-to-chemical nitrogen fixation. [ABSTRACT FROM AUTHOR]

A series of α-acyloxyacrylate esters are candidate monomers for bio-based polymers, converted from biomass feedstock. Polymers from these monomers are useful materials for bio-based plastics showing high heat resistance and transparency. In this paper, a new efficient method for α-acyloxyacrylate ester synthesis with a strong inorganic acid, heteropolyacid, is presented. The reaction in the presence of the heteropolyacid catalyst was carried out in liquid phase under mild conditions and showed higher productivity than that of the conventional synthesis with a typical organic acid, p-toluenesulfonic acid. Among the various heteropolyacids examined, α-Keggin-type tungsten-based phosphotungstic acid, H3PW12O40, showed the best performance, suggesting that the acid strength of the heteropolyacid is the crucial property for this reaction. We also found that pyruvate ester was consecutively converted into α-acyloxyacrylate ester via2,2-diacyloxypropionate ester. [ABSTRACT FROM AUTHOR]

The facile design and preparation of polyelectrolytes is a frontier topic in the fields of polymer science, energy storage devices and catalysis. Herein, linear water soluble cellulosic poly(protic ionic liquid) (CPIL) electrolytes were facilely and atom economically prepared after the dissolution of cellulose in the newly developed DBU/CO2/DMSO solvent system, followed by the simple addition of succinic anhydride under mild conditions. The DBU not only participated in the dissolution of cellulose as a solvent component, but also acted as an organocatalyst for the acylation reaction of cellulose with succinic anhydride, as well as a cation component in the targeted CPIL electrolytes. The reaction was optimized, and the effect of the reaction conditions on the chemical and physical properties of the CPILs was investigated. And then, as a proof of concept, the CPIL electrolyte aqueous solution was successfully used as the catalytic reaction media for the Knoevenagel condensation reaction. It was found that the reaction was homogeneous at the beginning, and the products could precipitate out from the media with the proceeding of the reaction, thus affording satisfactory filtration yields ranging from 56.7% to 93.8%. The solution properties of the CPIL aqueous solution were primarily investigated towards an in-depth understanding of the catalytic mechanism, by which a synergetic catalytic mechanism of the CPILs was proposed, and the reaction started with a nucleophilic addition reaction, and was then followed by a fast dehydration reaction. Finally, the direct reusability potential of the CPIL aqueous solution after the product filtration was also primarily investigated for the Knoevenagel condensation reaction. [ABSTRACT FROM AUTHOR]

In this work, we present a powerful approach for fast assessment of the potential biological impact of chemical processes on living organisms. This approach includes building bio-Profiles based on cytotoxicity data and calculating bio-Factors for chemical reactions. Bio-Profiles allow visual determination of substances with the highest and the lowest contributions to the "overall cytotoxicity" of a given chemical process, whereas bio-Factors indicate the quantitative change in the "overall cytotoxicity" during the process. This information provides the necessary initial description of the plausible biological impact of a given chemical reaction and can be used for subsequent optimization of the process from the viewpoint of toxicity of its components. To illustrate the proposed concept, measurements of biological activity were carried out for ca. thirty compounds in two cell lines and bio-Profiles were constructed for four practically relevant catalytic reactions (Suzuki cross-coupling, oxidative C–C coupling, the Friedel–Crafts reaction, and the Heck reaction). In addition, practical application of bio-Profiles was illustrated by the example of the Suzuki reaction and it showed the largest influence of aryl halides (X = Cl, Br, I), a modest influence of solvents and a small contribution of the catalyst to the overall toxicity profile. [ABSTRACT FROM AUTHOR]

Due to them being widely used batteries, a boom in the disposal of LiFePO4 (LFP) batteries is coming. Both pyrometallurgical repair and hydrometallurgical processes have been applied in the recycling of spent LFP batteries. The former has limited application due to its poor adaptability for spent LIBs with different chemistries or inconsistent degrees of damage, while the latter has poor economic returns due to the low added value of its products, ferric phosphate and lithium carbonate. In this study, a facile process for directly regenerating LiFePO4 from spent LFP cathode material involving acid leaching and hydrothermal synthesis is proposed. The results indicate that the acid leaching process of the spent LFP cathode material depends on the surface chemical reaction, and that 96.67% lithium and 93.25% iron leaching efficiency can be simultaneously achieved by control of the thermodynamic conditions. Additionally, through component control and a one-step hydrothermal process, a flake-like LFP cathode material was successfully regenerated directly from the leaching solution. The regenerated LFP cathode material shows good electrochemical performance, and its discharge capacity is 136 mA h g−1 at 0.1 C. After 300 cycles at 1 C, its capacity retention ratio is as high as 98.6%. Moreover, an economic evaluation indicates that the process is profitable. Therefore, the proposed approach in this study could help to avoid the complex element separation process and achieve the facile recycling of LFP cathode material, thus providing a novel and efficient method for the clean and economical recycling of spent LFP cathodes. [ABSTRACT FROM AUTHOR]

Lignin-based nanomaterials have attracted much attention in value-added functional material fields due to their green/sustainable nature; however, it is a challenge to control the morphology of lignin nanoparticles, and furthermore, to make them stable in organic solvent systems. Herein, for the first time we developed a green and simple approach for producing lignin nanorods, in addition to lignin nanospheres, both of which are stable in various organic solvents. The preparation process involves two steps: (1) lignosulfonate (LS) is fractionated into three fractions, namely, LS90, LS70, and LS40 using 90% ethanol, 70% ethanol and 40% ethanol sequentially; (2) lignin nanorods are obtained from the LS40 fraction, while lignin nanospheres are obtained from LS70 by an anti-solvent method. During the lignin self-assembly process, for the LS40 fraction, the lignin structures are in a flat oblate ellipsoid conformation, and the J-aggregation of their aromatic structures occurs on the flat sides of the oblate ellipsoid, leading to the formation of lignin nanorods. In contrast, for the LS70 fraction, lignin aggregation occurs randomly because of its near-spherical small ellipsoid conformation in solution, leading to the formation of lignin nanospheres. The entire preparation process of lignin nanorods and lignin nanospheres is simple, without the use of templates, complex chemical reactions and rigorous conditions. The lignin nanorods and lignin nanospheres exhibit excellent uniformity and dispersibility, and long-term stability in various organic solvents. This study not only presents a green, facile and economical approach for preparing lignin nanorods, as well as lignin nanospheres, but also provides a promising new value-added utilization pathway for lignosulfonate. [ABSTRACT FROM AUTHOR]

1,6-Hexanediol (HDO) is an important precursor in the polymer industry. The current industrial route to produce HDO involves energy intensive and hazardous multistage (four-pot–four-step) chemical reactions using cyclohexane (CH) as the starting material, which leads to serious environmental problems. Here, we report the development of a biocatalytic cascade process for the biotransformation of CH to HDO under mild conditions in a one-pot–one-step manner. This cascade biocatalysis operates by using a microbial consortium composed of three E. coli cell modules, each containing the necessary enzymes. The cell modules with assigned functions were engineered in parallel, followed by combination to construct E. coli consortia for use in biotransformations. The engineered E. coli consortia, which contained the corresponding cell modules, efficiently converted not only CH or cyclohexanol to HDO, but also other cycloalkanes or cycloalkanols to related dihydric alcohols. In conclusion, the newly developed biocatalytic process provides a promising alternative to the current industrial process for manufacturing HDO and related dihydric alcohols. [ABSTRACT FROM AUTHOR]

Exploration of the synergistic effect in catalysis upon simultaneous utilization of two sources of power, ultrasound and light, is barely explored and remains a challenging issue. A crucial reason behind this is the difficulty in designing and constructing a well-defined sonophotoreactor capable of taking advantage of the benefits of combining sonochemistry and photochemistry. Herein, we present our successful reactor and a detailed study regarding how the utilization of ultrasonication can act as a process intensification tool for selective and partial photooxidation of a biomass derived model compound, benzyl alcohol. The main outcome was the enhanced selectivity in the case of sonophotocatalysis compared to photocatalysis. This selectivity was ascribed to the effects derived from the cavitation phenomena, leading to phenomena such as hot spot formation and jetting. Our study can act as guidance towards understanding the unique effects of ultrasound irradiation as a hybrid process intensification method (HPIM) towards application in more complex chemical reactions and manipulation of the nanocatalysts' photoreactivity in catalytic valorization applications. [ABSTRACT FROM AUTHOR]

The present work deals with the production of cellulose nanoparticles through sonochemistry in various organic acidic media. The use of such organic acids represents low-environmental harm for the process. In contrast, the use of induced cavitation during chemical reaction balances the low effectiveness associated with the hydrolysis that uses organic acids, related to their low acidity. Overcoming the costs associated with extensive use of reagents and long reaction periods, which result in high-energy requirements, gives the value-added potential to an intrinsically green process. The selected organic acids were oxalic, maleic, and citric acid, chosen for their nature and their acid dissociation constant, as well as their availability in nature, which makes them green and cheap acidic media to produce cellulose nanocrystals. The acid concentration used was 0.2 moles for all the reactions; however, the pH, temperature, and reaction time were variated. The yields ranged between 20 and 40% depending on the reaction conditions, which are similar to typical cellulose nanocrystals yields. On the other hand, physicochemical analyses showed little differences between the different cellulose nanocrystals, thus indicating that the main benefit of having longer reaction times relies exclusively on the production yield. The resultant CNC surface contained carboxylic acid groups, which facilitate functionalization and dispersion in aqueous processing. [ABSTRACT FROM AUTHOR]

Gas-phase bioproduction, in which immobilized biocatalysts are employed and chemical reactions are performed in a gas phase, has attracted researchers' attention as a green process. However, there is difficulty in the employment of whole cell catalysts for gas-phase bioproduction due to the lack of a suitable cell immobilization method. Acinetobacter sp. Tol 5 is a unique bacterium, which is remarkably sticky and can be easily immobilized onto various material surfaces through the adhesive bacterionanofiber protein AtaA. In this study, we demonstrate the gas-phase bioproduction of (E)-geranic acid (GA), a high-value-added monoterpenoid, from geraniol using immobilized Tol 5 transformant cells, into which a gene involved in a (E)-GA synthetic pathway was introduced. Time course analysis of the liquid-phase bioproduction of (E)-GA revealed the inherent metabolism of Tol 5 involved in the degradation of (E)-GA. By disrupting the fadD4-ortholog gene, which encodes a key enzyme of the (E)-GA degradation, we successfully generated a (E)-GA-accumulating strain, Tol 5 ΔfadD4 (pGeoA). The immobilized cells of this mutant strain on a polyurethane support enabled the production of (E)-GA with a passive supply of gaseous geraniol in a batch gas-phase reaction. A major fraction of the (E)-GA, which was produced, was adsorbed onto the polyurethane support but easily extracted into ethanol, a safe solvent without environmental impact. This is the first example of gas-phase bioproduction of a complex and high-value-added compound. Tol 5 is a highly promising platform for gas-phase bioproduction. [ABSTRACT FROM AUTHOR]

This paper provides a broad strokes perspective on the evolution for the application of Life Cycle Assessment (LCA) within the pharmaceutical and chemical industries. This focus is mainly on the challenges faced to produce the needed inventory data and using the resulting LCA output in decision making, which are the backbone of any LCA estimation and practical application in industry. It also provides some of the insights the authors have derived over the last two decades of work in this area, and proposes a series of development needs within life cycle assessment as it becomes more integrated into decisionmaking in industry. [ABSTRACT FROM AUTHOR]

In this paper both the mechanistic and kinetic aspects of furfural formation from pentoses in aqueous acidic media have been reviewed. Based on the reviewed literature, a comprehensive reaction mechanism has been proposed consisting of more than one route, all starting from acyclic xylose, and involving alternately 1,2-enolization, β-elimination or isomerization via 1,2-hydride shift as key steps. Those studies that employ combined acid-base catalysts, soluble halide salts and trivalent cations in aqueous solutions appear to be most promising. Next, a detailed overview is presented of the results of kinetic studies on furfural formation from pentoses and furfural disappearance in aqueous acidic media. Although these results span over a very wide range of both experimental conditions and different kinetic models employed, an attempt has been made to present the published kinetic data in such a manner that it allows a global comparison. Since even in those cases where the reaction conditions seemed to be comparable, the reported kinetic constants often agree merely in the order of magnitude, thus, the validity of most of the data presented here is restricted to the specific conditions as used by each author. Additionally, a very concise overview is included of research on direct furfural production from lignocellulosic materials. In conclusion, the intricate set of reactions accompanying furfural formation from pentoses, although appearing well established in some aspects, is yet to be fully unraveled, especially with regard to the complex set of side and loss reactions seemingly involving largely unknown reaction intermediates. Such uncertainties are reflected in the contradictory kinetic models exploited and kinetic data presented in the literature, which still prevent a common and coherent interpretation. [ABSTRACT FROM AUTHOR]

It is a great challenge to achieve a useful reaction under benign conditions. In this paper, a highly efficient method for copper-catalyzed conjugations of o-aromatic diamines with ketones has been developed using benign chemistry. Interestingly, the conjugation between the biological small molecules worked very well. [ABSTRACT FROM AUTHOR]

Carbosilylation is a straightforward procedure to install both silyl and organic functional groups onto organic molecules. For example, allylsilylation of alkenes with allylsilanes affords 5-silyl-1-pentene derivatives. In this review paper, catalytic allylsilylations and arylsilylations of alkenes, alkynes, and cyclic acetals are summarized. Specific catalyses of Lewis and Brønsted acids, such as HfCl4 and proton-exchanged montmorillonite, will be discussed. Intramolecular reactions as well as intermolecular allyl- and arylsilylations have been achieved. In the case of the Brønsted acid catalyst, cationic Si species generated and acted as catalytically active species. The structure of the cationic Si species depends on the type of Brønsted acid used. A disilyl cation was proposed as the catalytically active site for carbosilylations of alkenes and alkynes, while a monomeric Si species was active for allylsilylation of cyclic acetals. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of furfural (a biomass-derived platform compound, C＝O versus C＝C) is an important reaction for the production of chemical intermediates widely used in the polymer industry. Herein, we report three non-precious intermetallic compounds (IMCs) (Ni3Sn1, Ni3Sn2 and Ni3Sn4) derived from a layered double hydroxide (LDH) precursor, which are characterized by a highly uniform dispersion of IMC nanoparticles and display surprisingly improved catalytic performance toward the selective hydrogenation of furfural (C＝O) to furfuryl alcohol. In particular, the Ni3Sn2 IMC shows optimal catalytic behavior (conversion: 100%; selectivity: 99%), which exceeds that of reported non-precious metal catalysts and is even comparable to that of noble metal catalysts (e.g., Au, Pd and Pt). A combinative investigation based on in situ FT-IR, XANES and Bader charge studies verifies electron transfer from Sn to Ni, facilitating the activation of adsorption of the C＝O bond on the Ni top site, whilst inhibiting the adsorption of C＝C. Both experimental studies (in situ FT-IR and catalytic evaluations) and theoretical calculations (DFT calculations and microkinetic modeling) reveal a vertical adsorption configuration of furfural molecules over the Ni3Sn2 IMC, followed by the first hydrogenation at the carbon atom (the rate-determining step) and the second hydrogenation at the oxygen atom. This detailed study of the structure-selectivity relationship is substantiated by virtue of establishing the adsorption configuration of the substrate and the reaction pathway, which paves the way for the rational design and development of high-efficiency heterogeneous catalysts for selective hydrogenation reactions. [ABSTRACT FROM AUTHOR]

Traditionally, conventional heat has been required for a large proportion of the oxidation and degradation process to utilise lignin from biomass. A photocatalysis system which is considered as a novel and green strategy for chemical reactions has been applied and a photo-MnO2 catalytic lignin oxidation method has been developed. In this study, we investigated a promising photocatalytic heterogeneous system for lignin oxidation. Recyclable MnO2 which is readily available and blue light which is a hazardless light are used in this system. 1-Phenylethanol was used as a model compound to study the suitable conditions for this system. After optimizing the reaction conditions, organosolv lignin, kraft lignin, and alkali lignin were applied to this system and the successful oxidation of lignins and their further degradation were shown. [ABSTRACT FROM AUTHOR]

Efforts to understand the reaction mechanisms of cellulose pyrolysis have been stymied by short reaction times and difficulties in probing the condensed phase of cellulose intermediate products. Using time-resolved yields of both volatile and non-volatile products of pyrolysis, we demonstrate that cracking reactions generate anhydro-oligosaccharides while subsequent reactions produce levoglucosan from these anhydro-oligosaccharides. Eventually, cracking of anhydro-oligosaccharides is eclipsed by levoglucosan-producing reactions. These reactions compete with other reactions that produce light oxygenates and non-condensable gases. The relative reaction rates in this competition limit levoglucosan yields from cellulose pyrolysis to approximately 60 wt%. [ABSTRACT FROM AUTHOR]

This paper reports the application of an extremely facile methodology for monitoring the progress of chemical reactions. This has been exemplified by successfully following the progress of a controlled ring opening polymerisation of ε-caprolactone which has been successfully monitored at high temperature (＞100 °C), using a direct, on-line measurement of the system dielectric properties. The data was obtained via the use of a coaxial probe in a standard quick fit reaction flask. The on-line measurement has been related to a calibration curve and from this comparison it has been shown that dielectric data can be used to predict the molecular weight of the polymer at a particular point in the reaction. This in turn allowed isolation of a product with desired molecular weight and polydispersity index values, by enabling the reaction to be terminated prior to the point where reaction control is lost due to the appearance of side reactions. These on-line measurements were corroborated by comparison to conventional and accepted off-line measurement techniques. [ABSTRACT FROM AUTHOR]

This paper deals with a novel, efficient and environmentally friendly synthesis of dialkyl haloalkylphosphonates via a microwave-assisted Michaelis–Arbuzov reaction. The approach is solventless, requires only one equivalent of each of the starting compounds, and provides high yields of pure products from which the impurities are easy to remove. The process has been optimised for batch and flow reactors and is especially profitable for the production of key intermediates in synthesis of Ethephon or acyclic nucleoside phosphonates such as adefovir, tenofovir, and cidofovir. [ABSTRACT FROM AUTHOR]

Furfural production through traditional processes is accompanied by acidic waste stream production and high energy consumption. Modern furfural production process concepts will have to consider environmental concerns and energy requirements besides economics, moreover will have to be integrated within widened biorefinery concepts. In this paper, some particular aspects of the chemistry of d-xylose reaction to furfural are addressed, with the aim to clarify the reaction mechanism leading to furfural and to define new green catalytic pathways for its production. Specifically, reducing the use of mineral acids is addressed by the introduction of alternative catalysts. In this sense, chloride salts were tested in dilute acidic solutions at temperatures between 170 and 200 °C. Results indicate that the Cl−ions promote the formation of the 1,2-enediol from the acyclic form of xylose, and thus the subsequent acid catalyzed dehydration to furfural. For this reason the presence of Cl−ions led to significant improvements with respect to the H2SO4case. The addition of NaCl to a 50 mM HCl aqueous solution gave 90% selectivity to furfural. Among the salts tested FeCl3showed very interesting preliminary results, producing exceptionally high xylose reaction rates. [ABSTRACT FROM AUTHOR]

Ionic liquids are studied intensively for electrochemical applications and more specifically for the electrodeposition of metals. In this paper the electrochemical stability of a deep-eutectic solvent based on choline chloride and ethylene glycol is studied over longer periods of electrolysis. The formation of several decomposition products such as 2-methyl-1,3-dioxolane was observed. Possible mechanisms for the formation of these products are given: some products involve a reaction at either the anode or the cathode, while others can be explained by consecutive reactions of reaction products formed at both electrodes. A range of chlorinated products like chloromethane, dichloromethane and chloroform could be detected as well. This is remarkable as evolution of chlorine gas at the anode is not observed. The formation of the chlorinated products is ascribed to the existence of the Cl3−ion in the solution. The presence of the Cl3−ion was observed photometrically. The presence of chlorinated products gives rise to a larger environmental impact and higher risks for health and safety, and it questions the “greenness” of these ionic liquid analogues. To reduce the decomposition of the solvent, water and easily oxidizable acids were added as ‘sacrificial agents’. Their influence on the formation of 2-methyl-1,3-dioxolane was quantified. However, the addition of the sacrificial agents did not improve the stability of the solvent. Addition of formic acid reduced the formation of 2-methyl-1,3-dioxolane but chlorinated products could still be detected. Water reduced the formation of chlorinated products. [ABSTRACT FROM AUTHOR]