Benign Solvent Research Articles

Benign solvents for recycling and re-use of a multi-layer battery pouch

This article describes a process for the repair and re-use of an aluminium-containing pouch used as an outer casing for a Lithium-ion battery cell.

Atom-economical, catalyst-free hydrosulfonation of densely functionalized alkenes: access to oxindole-containing sulfones

A facile, atom-economical, catalyst-free protocol for the hydrosulfonation of densely functionalized alkenes with sulfinic acids in an environmentally benign solvent system at ambient temperature is described.

Palladium Nanoparticles Supported on Cellulosic Paper as Multifunctional Catalyst for Coupling and Hydrogenation Reactions.

Hallmark of a successful catalyst is its high efficiency, economic aspects, operational simplicity, extensive reusability, higher environment friendliness, and potential use in multiple industrial applications. Herein, a facile protocol involving a catalyst with Pd nanoparticles supported on cellulose paper (also known as a "dip-catalyst") for the hydrogenation of a series of quinolines, nitroarene, and C-C bond formation reactions in most benign solvents such as water is described. The mere insertion/removal of the "dip-catalyst" strip enables instantaneous start/stop of the reaction, which enhances its reusability and ease of separation of products. Cellulose paper (CP) strips decorated with Pd nanoparticles (Pd/CP) are prepared by the reduction of K2 PdCl4 soaked strips using formic acid as reductant. The resulting spherical shaped Pd particles, confirmed by scanning electron microscopy, form stable catalysis centers on the support. XRD signature confirms the crystallinity of the Pd nanoparticles and the TEM images display 15-20 nm size particles uniformly decorating CP. X-ray photoelectron spectroscopy indicates the formation of metallic Pd. The catalyst is tested for the C-C bond formation reactions. Pd/CP catalyzed Suzuki-Miyaura coupling reaction demonstrate >99% conversion with optimum selectivity. On the other hand, Mizoroki-Heck reaction produced 87% conversion with the reaction of 4-methoxycarbonyl phenylboronic acid and iodobenzene in ethanol:water (1 : 1 v/v) using KOH as base. The developed Pd/CP construct produces >99% of the pyridine-ring hydrogenated product on quinoline hydrogenation using tetrahydroxydiboron (THDB) as the hydrogen source. Diverse and highly reducible functional groups were also evaluated for transfer hydrogenation, which demonstrates a high efficiency in terms of both reactivity and selectivity. The used catalysts are recyclable for the multiple cycles.

Highly efficient extraction of indole from model wash oil by using environmentally benign deep eutectic solvents

Indole is an important organic synthesis intermediate derived from the wash oil fraction in coal tar. Deep eutectic solvents (DESs) have been widely used in the separation field due to their unique properties such as easy preparation, low cost, green and high extraction efficiency, and reusability. In this study, five DESs, including tetramethylammonium chloride/ethylene glycol (TMAC/EG), triethylmethylammonium chloride/ethylene glycol (TEMAC/EG), tetraethylammonium chloride/ ethylene glycol (TEAC/EG), tetrapropylammonium chloride/ethylene glycol (TPAC/EG), tetrabutylammonium chloride /ethylene glycol (TBAC/EG) were prepared and used to extract indole from model wash oil. The results showed that TPAC/EG exhibited the best extraction ability under the same conditions. Then, the main experimental parameters such as mass ratio of DES to model wash oil, extraction temperature, extraction time, standing time and initial concentration of indole, were investigated when using TPAC/EG as extractant. In optimal conditions (25℃, 5 min, mass ratio 1:8), the extraction efficiency, selectivity and distribution coefficient for indole were 90.51%, 79.21% and 61.12, respectively. Moreover, removing neutral oil with petroleum ether, the purity of indole further reached 96.63%, which was much higher than that in the previous studies reported. In addition, accessible and environmentally friendly water instead of diethyl ether was used to regenerate the DES. Reused four times, the TPAC/EG extraction ability for indole almost did not change. Finally, the mechanism of extraction process was investigated by FT-IR analysis. This work provides a new route for extraction and recovery indole from wash oil.

Synthesis and Applications of Carbohydrate-Based Organocatalysts.

Organocatalysis is a very useful tool for the asymmetric synthesis of biologically or pharmacologically active compounds because it avoids the use of noxious metals, which are difficult to eliminate from the target products. Moreover, in many cases, the organocatalysed reactions can be performed in benign solvents and do not require anhydrous conditions. It is well-known that most of the above-mentioned reactions are promoted by a simple aminoacid, l-proline, or, to a lesser extent, by the more complex cinchona alkaloids. However, during the past three decades, other enantiopure natural compounds, the carbohydrates, have been employed as organocatalysts. In the present exhaustive review, the detailed preparation of all the sugar-based organocatalysts as well as their catalytic properties are described.

Comparative evaluation of liquid–liquid equilibria for extraction of 2,2,3,3‐tetrafluoro‐1‐propanol from water by a ZIF‐8‐porous ionic liquid

AbstractBACKGROUND2,2,3,3‐Tetrafluoro‐1‐propanol (TFP) is a benign solvent and widely used in the electronics industry as a cleaning agent. Because water and TFP can form an azeotropic mixture, it consumes energy to separate TFP from its aqueous mixtures using conventional distillation.RESULTSIn this work, the zeolitic imidazolate framework‐8 porous ionic liquid (ZIF‐8‐PIL) and the ionic liquid (IL) N‐butyl pyridinium bis(trifluoromethyl sulfonyl) imide ([Bpy][NTf2]) are used as extractants to extract TFP from its aqueous solution. ZIF‐8‐PIL was synthesized by ZIF‐8 and IL [Bpy][NTf2]. The liquid–liquid equilibrium (LLE) data for the two systems (water + TFP + ZIF‐8‐PIL/IL) were determined at 298.15, 308.15 and 318.15 K under 101.3 kPa. The selectivity (S) and distribution coefficient (D) were examined to assess the extractive performance of ZIF‐8‐PIL and IL. The non‐random two‐liquid (NRTL) model was applied to fit the tie‐line data of the investigated mixtures.CONCLUSIONThe results demonstrate that ZIF‐8‐PIL is a suitable extractant to separate TFP with values of S and D greater than unity. The NRTL model has better correlation performance for the ternary systems with root mean square deviation lower than 0.01. The obtained parameters satisfy the minimum state of the mixed Gibbs free energy, which indicated that the model parameters are reliable. © 2021 Society of Chemical Industry (SCI).

Cascade Wolff Rearrangement/Acylation: A Metal-Free and Eco-Friendly Approach for 4-Hydroxy-pyrazolo[3,4-b]pyridin-6-ones and N-Pyrazole Amides Synthesis from 5-Aminopyrazoles and α-Diazoketones.

A highly chemoselective cascade Wolff rearrangement/acylation reaction between 5-aminopyrazoles and diazo compounds has been developed. The protocol can facilitate the switchable synthesis of 4-hydroxy-pyrazolo[3,4-b]pyridin-6-ones and N-pyrazole amides with the merits of a broad substrate scope, high functional group compatibility, and green and sustainable performance manner. All reactions proceeded efficiently without any catalyst and additives (acid and base) and resulted in the release of benign N2, wherein diethyl carbonate served as a green benign solvent.

Random and aligned electrospun poly(ε-caprolactone) (PCL)/poly(1,8-octanediol-co-citrate) (POC) fiber mats for cardiac tissue engineering using benign solvents

• Electrospinning of PCL/POC using benign solvents. • Random and aligned PCL/POC fiber mats with suitable morphology. • Properties depend on blend composition, fiber orientation, and crosslinking density. • PCL/POC 2:1 ratio showed most suitable properties. • Fiber alignment led to improved cell attachment. Cardiac tissue engineering (CTE) is a rising field of research aiming to provide strategies to repair or regenerate damaged heart tissue after events like myocardial infarction. Here, poly(1,8-octanediol-co-citrate) (POC) has been blended with poly(ε-caprolactone) (PCL) and the blend polymer was electrospun using the benign solvents acetic acid and formic acid to develop cardiac patches for CTE. The fiber mats were thermally crosslinked under mild conditions. Random and aligned PCL/POC fiber mats were investigated with regard to their morphological and physico-chemical properties, their degradation behavior, and their cytocompatibility in vitro. Homogenous and defect-free fibrous structures with average fiber diameters of 0.61 and 1.11 µm were observed for 2:1 and 1:1 ratios of PCL/POC blends. The wettability as well as mechanical properties of the PCL/POC fiber mats were dependent on blend composition, crosslinking treatment, and fiber orientation. While the wettability of the fiber mats was in a suitable range, the mechanical properties even exceeded necessary values for CTE after 14 days of incubation in Dulbecco’s phosphate buffered saline (DPBS). The post-crosslinking of the fiber mats also increased the degradation resistance resulting in less acidic leaching and more stable fibers after 28 days in DPBS. Cytocompatibility tests with C2C12 cells demonstrated an excellent cytocompatibility of PCL/POC blends with a PCL/POC ratio of 2:1. Based on the obtained data, PCL/POC fiber mats made from benign solvents showed promising properties for applications in CTE as cardiac patches and should be subjected to further research to elucidate their in vitro and in vivo potential.

PH-Mediated Selective Synthesis of N-Allylic Alkylation or N-Alkylation Amines with Allylic Alcohols via an Iridium Catalyst in Water.

Amination of allylic alcohols is an effective approach in the facile synthesis of N-allylic alkylation or N-alkylation amines. Recently, a series of catalysts were devised to push forward this transformation. However, current synthetic methods are typically limited to achieve either N-allylic alkylation or N-alkylation products via a certain catalyst. In this article, a pH-mediated selective synthesis of N-allylic alkylation or N-alkylation amines with allylic alcohols via an iridium catalyst with water as the environmental benign solvent is revealed, enabling the miscellaneous synthesis of N-allylic alkylation and N-alkylation products in outstanding yields. Furthermore, a gram-scale experiment with low catalyst loading offers the potential to access a distinct entry for the synthesis of the antifungal drug naftifine.

Stable Pd(0) Complexes with Ferrocene Bisphosphanes Bearing Phosphatrioxaadamantyl Substituents Efficiently Catalyze Selective C‐H Arylation of Benzoxazoles by Aryl Chlorides

AbstractVersatile applications and unique performance of 1,1’‐bis(diphenylphosphanyl)ferrocene (dppf) in coordination chemistry and catalysis prompted the search for its analogs. This contribution describes the synthesis of the first donor‐unsymmetric dppf congeners bearing bulky and rigid 1,3,5,7‐tetramethyl‐2,4,6‐trioxa‐8‐phosphaadamantyl (CgP) donor groups, viz. Ph2PfcPCg (1) and Ph2PfcCH2PCg (2; fc=ferrocene‐1,1’‐diyl). Bis‐phosphanes 1 and 2 were converted into air‐stable Pd(0) complexes, [Pd(ma)(L^L)] (L^L=1 and 2; ma=maleic anhydride). Together with [Pd(ma)(dppf)], these complexes were applied as catalysts in Pd‐catalyzed C−H arylation of benzoxazoles with aryl chlorides in n‐butanol as an environmentally benign solvent. Among all catalysts tested in this study, complex [Pd(ma)(2)] performed the best, providing a high‐yield and selective synthesis of 2‐arylbenzoxazoles from a range of the generally less reactive chloroarenes at low catalyst loading (typically 1 mol.%). Under similar conditions, the structurally related heterocycles (e. g., 1‐methylbenzimidazole and benzothiazole) did not react.

Carboxylate functionalized imidazolium-based zwitterions as benign and sustainable solvent for cellulose dissolution: Synthesis and characterization

Cellulose is most abundant biopolymer on earth and can be utilized as sustainable resources for many applications, however, their utilization at great extent is limited due to lack of benign and recyclable solvent. While N-methylmorpholine-N-oxide (NMMO), used in Lyocell process, is thermally unstable and may undergoes runaway conditions, commercialization of ionic liquid as solvent still suffers from recyclability issues. Herein, we present the synthesis of a series of zwitterions, composed of tethered alkyl imidazolium cation and carboxylate anion, and investigated their cellulose dissolution characteristics. Effect of alkyl chain length of imidazolium ring on its dissolution efficiencies was studied and amongst synthesized zwitterions, the hexanoate derivatives exhibited 13% (w/w) cellulose dissolution at 100–125 °C. Thermal stability of zwitterions and their cellulose solution was characterized by DSC-TGA and found to be more stable than the NMMO and Lyocell solution. Rheological studies indicate that cellulose solution in zwitterions are viscoelastic and in spinnable range of fibre processing. Structural and morphological characterization of regenerated cellulose using elemental analysis, FTIR, DSC-TGA, GPC, XRD and SEM showed that zwitterions have no adverse effect on its physicochemical and morphological properties. A method for recovery and purification of solvent after cellulose dissolution and regeneration is also presented.

N-butyl pyrrolidone/ionic liquid mixtures as benign alternative solvents to N-methyl pyrrolidone for the synthesis of polyaramids

N-methyl pyrrolidone (NMP) is a polar aprotic solvent that is critical for the production of polyaramids. However, due to its reprotoxicity and pending REACH restrictions, a benign alternative is needed. A mixture of N-butyl pyrrolidone (NBP) and the ionic liquid [C8MIm][Cl] is proposed as a promising candidate to replace NMP. This organic electrolyte solution provides a green approach to polyaramid synthesis.

Ethyl lactate production by reactive distillation - optimization of reaction kinetics and energy efficiency.

Background: Ethyl lactate is an environmentally benign solvent, which could substitute petrol-based volatile organic compounds (VOCs) in many applications if production costs are reduced. It is usually produced by the esterification of lactic acid with ethanol - two important chemical building blocks of biorefineries that are available at industrial scale. Reactive distillation is a promising alternative production process, which utilises process intensification to increase energy efficiency and space-time yield by enhancing the reaction kinetics. Methods: In this work, process intensification of ethyl lactate production by means of distillation was analysed with special focus on the efficient separation of water.Different setups were evaluated. The feedstock requirements were studied and the process was optimized regarding reaction kinetics in experiments on laboratory level. The preparation of anhydrous starting mixtures for ethyl lactate formation was tested in batch experiments and applied to reactive distillation. The simultaneous distillation was optimized and assessed for its energy efficiency. For this purpose, integrated reactive distillation was compared to a simple setup for distillation enhanced esterification. Results: It was found that an optimized serial setup of reactors and distillation steps can offer similar process intensification at a lower distillate rate compared to simultaneous reactive distillation and is therefore more energy efficient. Moreover, the serial setup is more flexible and straight-forward to regulate and scale-up. Conclusions: Based on the experimental results, the optimal setup and parameters of a continuous process for ethyl lactate production by distillation enhanced esterification was presented.

Metal‐Free One‐Pot Synthesis of 2‐(2‐Hydrazinyl) Thiazole Derivatives Using Graphene Oxide in a Green Solvent and Molecular Docking Studies

AbstractAn efficient, one‐pot three‐component reaction in the synthesis of a wide range of 2,4‐disubstituted hydrazinyl thiazole scaffolds in ethanol at room temperature has been developed by the reaction of carbonyl compounds, phenacyl bromides, and thiosemicarbazide, using graphene oxide (GO) as a catalyst. The present catalytic method has many significant advantages such as shorter reaction time, broad substrate scope, low catalyst loading, environmentally benign solvent media, easy handling, and operational simplicity at room temperature. The products are identified based on their various spectroscopic data. The GO catalyst has a high reusability rate and is simple to recover. A mechanistic study suggests that the reaction takes placeviaa thiosemicarbazone intermediate, which is isolated and confirmed in this study using spectroscopic techniques. Thereafter, a molecular docking study has been performed to evaluate the binding affinity of hydrazinyl thiazole derivative as a possible inhibitor on the protein active site of human α‐amylase and glucosamine 6‐phosphate synthase

An efficient Brønsted acid ionic liquid catalyzed synthesis of novel spiro1,2,4-triazolidine-5-thiones and their photoluminescence study

We have synthesized a novel Bronsted acidic ionic liquid, 1-(2-hydroxyethyl)-1-(4-sulfobutyl)piperidin-1-ium hydrogen sulfate, [HEPiPYBSA]+HSO4− and explored its catalytic efficiency for synthesis of indenoquinoxalone tethered spiro-1,2,4-triazolidine-5-thiones from reaction of 11H-[1,2-b]quinoxalin-11-one and thiosemicarbazide. The most stable geometries of synthesized ionic liquid (IL) [HEPiPYBSA]+ HSO4− were obtained through systematically optimization by the DFT theory at B3LYP/6-31G* level. A photoluminescence study of the synthesized spiro-1,2,4-triazolidine-5-thiones revealed a remarkable fluorescent activity. The advantages of the present method are a reusable hydrophilic green catalyst, mild reaction conditions, use of benign solvent system, short reaction span, high atom economy and wide substrate scope.

Dihalogenation of Alkenes Using Combinations of N‐Halosuccinimides and Alkali Metal Halides

AbstractA simple, efficient and eco‐friendly method for the vicinal dihalogenation of alkenes is described. The reaction is performed with a combination of a N‐halosuccinimide and an alkali metal halide using environmentally benign solvents such as acetic acid and ethyl acetate. Purification steps are avoided, and pure products are usually obtained after a simple aqueous workup.

DMAP-catalyzed Efficient and Convenient Approach for the Synthesis of 3,3′-(Arylmethylene)bis(2-Hydroxynaphthalene-1,4-Dione) Derivatives

For the first time the 4-dimethylaminopyridine (DMAP) catalyzed straightforward and efficient procedure has been developed for the synthesis of 3,3′-(arylmethylene) bis(2-hydroxynaphthalene-1,4-dione) derivatives starting from lawsone (2-hydroxy-1,4-naphthoquinone) and a variety of (hetero)aromatic aldehydes in ethanol under microwave irradiation. Three of nine synthesized compounds are new. This method provides notable advantages over existing procedures including use of non-traditional basic catalyst and environmentally benign solvent, mild reaction conditions, excellent yields, short reaction time and simple workup.

Foundry-compatible high-resolution patterning of vertically phase-separated semiconducting films for ultraflexible organic electronics

Solution processability of polymer semiconductors becomes an unfavorable factor during the fabrication of pixelated films since the underlying layer is vulnerable to subsequent solvent exposure. A foundry-compatible patterning process must meet requirements including high-throughput and high-resolution patternability, broad generality, ambient processability, environmentally benign solvents, and, minimal device performance degradation. However, known methodologies can only meet very few of these requirements. Here, a facile photolithographic approach is demonstrated for foundry-compatible high-resolution patterning of known p- and n-type semiconducting polymers. This process involves crosslinking a vertically phase-separated blend of the semiconducting polymer and a UV photocurable additive, and enables ambient processable photopatterning at resolutions as high as 0.5 μm in only three steps with environmentally benign solvents. The patterned semiconducting films can be integrated into thin-film transistors having excellent transport characteristics, low off-currents, and high thermal (up to 175 °C) and chemical (24 h immersion in chloroform) stability. Moreover, these patterned organic structures can also be integrated on 1.5 μm-thick parylene substrates to yield highly flexible (1 mm radius) and mechanically robust (5,000 bending cycles) thin-film transistors.

Mechanistic Investigations into the Catalytic Levulinic Acid Hydrogenation, Insight in H/D Exchange Pathways, and a Synthetic Route to d8-γ-Valerolactone

γ-Valerolactone (GVL) is readily accessible by catalytic hydrogenation of carbohydrate-derived levulinic acid (LA) and is an attractive biobased chemical with a wide range of applications in both the chemical (e.g., as biomass-derived solvent) and the transportation fuel sector. In this study, we used isotopic labeling experiments to provide insights into the catalytic hydrogenation pathways involved in the conversion of LA to GVL under different reaction conditions using water as an environmentally benign solvent and Ru/C as a readily available catalyst. 2H NMR experiments combined with quantum chemical calculations revealed that deuterium atoms can be incorporated at different positions as well as the involvement of the different intermediates 4-hydroxypentanoic acid and α-angelica lactone (α-AL). The insight provided by these studies revealed an as of yet unexploited sequential deuteration route to synthesize fully deuterated LA and GVL. The route starts by the conversion of LA to α-AL followed by a selective deuteration of the acidic protons of α-AL by H/D exchange with D2O. Subsequent ring-opening in D2O (d2-AL to d3-LA) and exchange of the remaining protons of d3-LA via a keto-enol tautomerization by heating in D2O under acidic conditions gives d8-LA. Finally, the d8-LA is catalytically reduced at low temperature using Ru/C with D2 in D2O to d8-GVL.

Task-specific deep eutectic solvents for the highly efficient and selective separation of H2S

Developing environmental benign and efficient solvents for the natural gas sweetening is of great significance to the development of green chemistry. However, there is no task-specific deep eutectic solvents (DESs) for H2S absorption so far. Herein, we have for the first time developed a series of task-specific DESs for the selective separation of H2S, in which quaternary ammonium salts with free tertiary amine groups are designed as hydrogen bond acceptors (HBAs) and azoles as hydrogen bond donors (HBDs). Density, viscosity, and thermal decomposition temperature, as well as the solubility of H2S (0–1.0 bar), CO2 (0–1.0 bar), and CH4 (0–5.0 bar) were systematically determined. NMR paired with theoretical calculations are applied to characterize the interaction mechanism of H2S and DESs. A reaction equilibrium thermodynamic model (RETM) with a 1:2 stoichiometric reaction mechanism was screened to correlate H2S solubility data. It is found that [C4-TMHDA][Cl]-Im could achieve up to 0.996 mol H2S per mol DES at 303.2 K and 1.0 bar. Moreover, the captured H2S can be easily stripped out at elevated temperature and reduced pressure, with negligible loss in H2S capacities during four absorption–desorption cycles. The results obtained in this work indicate that these DESs are promising candidates for efficient and selective separation of H2S and CO2 from natural gas. This work provides novel insights into the future design of high-performance task-specific DESs for the capture of H2S.