Low-boiling Solvents Research Articles

Enzymatic synthesis of aromatic biobased polymers in green, low-boiling solvents

Given the urge to accelerate the substitution of petrol-derived solvents not only in more traditional fields like pharmaceuticals, personal care, or electronics but also in innovative research processes, this work focuses on the utilisation of four biobased solvents as media for the enzymatic synthesis of aliphatic-aromatic polyesters. As building blocks, the lignin-derived diethyl-2,4-pyridinedicarboxylate was selected as the potentially biobased, aromatic component while more classical diols such as 1,4-butanediol and 1,8-octanediol were used as the aliphatic portion. Results show that among the tested green solvents (cyclohexanone, phenetole, anisole and eucalyptol), the most suitable medium for lipase B from Candida antarctica-catalysed polycondensation reactions was eucalyptol that allowed reach monomer conversions >95 % and number average molecular weights up to 3500 g·mol−1. On the other hand, cyclohexanone led to the lowest monomer conversions (<80 %) and molecular weights (Mn<500 g·mol−1) confirming once again the unsuitability of ketone-containing solvents for enzymatic esterification and transesterification reactions. The lipase could be used up to three times, in eucalyptol as a solvent, without a significant decrease in monomer conversion or molecular weight.

Boosting catalytic performance of Amberlyst‐15 by modulating surface properties for synthesis of 5-hydroxymethylfurfural from high-concentration fructose

The large-scale production of 5-hydroxymethylfurfural (HMF), a “sleeping giant” in sustainable chemistry, is frequently hampered by the severe formation of humins during the acid-catalyzed dehydration of high-concentration fructose. In this work, we demonstrate that the HMF yield could be remarkably enhanced by boosting the catalytic performance of a commercially used Amberlyst-15 solid acid organocatalyst, wherein the formation of humins could be effectively inhibited. We show that the modification of Amberlyst-15 with a typical cationic surfactant (i.e., cetyltrimethylammonium bromide (CTAB)) via charge interaction between sulfonic acid groups and quaternary ammonium cations led to an improved surface hydrophobicity and a reduced Brønsted acid density on the modified catalyst, thereby contributing to a complete suppression of HMF rehydration and remarkable suppression of humin formation via paths of both etherification-dehydration-condensation and degradative-condensation of fructose and/or HMF. As a result, the catalytic conversion of fructose over the CTAB-modified Amberlyst-15 catalyst in a low-boiling mixed solvent composed of 1,4-dioxane and H2O at 140 °C within 2 h led to high HMF yields in range of 53.3 ∼ 63.1 mol% in converting high-concentration fructose (10.0 ∼ 50.0 wt%), wherein an average enhancement of 20 mol% in product yield was achieved when compared with that over un-modified Amberlyst-15. Moreover, the adsorption of humins on solid catalyst was significantly reduced due to the enhanced surface hydrophobicity and alleviated formation of humins, which accounted for a stable catalytic performance of the modified Amberlyst-15 catalyst for at least five runs. This work highlights the rational adjustment of the surface wettability of a commercial solid acid catalyst to suppress the undesired humin formation for future HMF biorefinery.

Carbonate swollen lithiated Nafion electrolyte for quasi-solid-state lithium–sulfur batteries

In the present study we developed a thin, mechanically flexible and safe high-energy battery for smart textiles, demonstrating a pathway to eliminate toxic and low-boiling solvents and guiding a development towards solid state batteries.

Synthesis of CdSe Quantum Dots in Two Solvents of Different Boiling Points for Polymer Optical Fiber Technology.

Polymer materials find many applications in various industries. Efforts are being made to obtain structures with increasingly better properties. It is necessary not only to obtain new materials but also to modify existing structures. Such is the situation with polymer optical fibers. The widespread use of polymer optical fibers is impossible, due to their very high optical losses compared to glass optical fibers. The solution to this problem can be the manufacturing of polymer active optical fibers. Active fibers are the basic components of fiber optic amplifiers and lasers that allow the direct amplification of light inside the fiber. In order for their operation to be the most effective, it is necessary to use dopants. The most commonly used are lanthanide ions isolated from the polymer network, active organic dyes, and quantum dots. These dopants are characterized by very high luminescence and long glow times. Quantum dots of CdSe are made using two organic solvents that differ in boiling points-hexane (a low-boiling solvent with a boiling point of 69 °C) and 1-octadecene (a high-boiling solvent with a boiling point of 315 °C). This work aims to test whether the type of solvent used to obtain quantum dots affects the doping capabilities of polymer structures, from which optical fibers can then be drawn.

Optimal design and multicriteria comparison of extractive distillation processes for separating of a quaternary low-boiling solvent mixture

This article mainly explores the eco-efficient separation of a complex quaternary azeotropic mixture of methanol, n-hexane, ethyl acetate and ethanol from a pharmaceutical enterprise via extractive distillation. To this end, aniline (AN) and ethylene glycol (EG) are selected as two alternative entrainers based on the relative volatility curve. Two conventional processes with AN and EG (AN-CED and EG-CED) are proposed and optimized with total annual costs (TAC) as a goal by simulated annealing algorithm. To improve energetic and economic performance, two optimal strengthening processes, that is, low-pressure side-stream extractive distillation process with AN (AN-SSED) and dividing-wall extractive distillation process with EG (EG-EDWC) are also developed for the first time. Finally, the four processes are compared in terms of economics, CO2 emissions and inherent safety. The results show that the AN-SSED process is recommended due to the best economic, environmental and inherent safety properties, as reflected by the lowest TAC, CO2 emission and process route index (PRI). It can reduce TAC by 9.38%, CO2 emission by 26.34% and PRI by 38.02% relative to the EG-EDWC process. Remarkably, the EG-EDWC process can reduce TAC by 11.12% than AN-CED process and 6.9% than the EG-CED process, but it is inferior to the two conventional processes in terms of CO2 emissions and inherent safety.

Boosting the photovoltaic performance of doctor-bladed organic solar cells using a low-boiling solvent additive

Boosting the photovoltaic performance of doctor-bladed organic solar cells using a low-boiling solvent additive

Development of an Inline Tube-in-Tube Solvent Exchanger for Continuous-Flow Swap from High- to Low-Boiling Solvent

Solvent swap from high- to low-boiling solvents still presents a huge challenge in the development of multistep continuous-flow processing. Herein, a miniaturized inline tube-in-tube solvent exchanger combining intensified convective mass transfer with droplet evaporation is presented. The design involves intimate contact between droplet and gas phases in countercurrent mode within a mesofluidic tube. Its solvent removal performance was evaluated by using pure solvents and binary mixtures. The results revealed that the commonly used solvents with low to medium boiling points (Tb < 100 °C) can be completely evaporated at room temperature without the need of heating. Significantly, high-boiling solvents can be efficiently removed at temperatures much lower than their boiling points. Its capacity for the separation of binary mixtures was corroborated by removing dichloromethane from a 50:50 mol % dichloromethane–dimethylformamide mixture and acetic acid from a 50:50 mol % p-nitroacetophenone–acetic acid mixture. A computational fluid dynamics (CFD) model based on the phase field approach was developed to quantitatively describe the droplet evaporation process, providing indepth evaporation dynamics and furthering our understanding on the concomitant phase change phenomenon. The comparison with other types of evaporators highlights its superior evaporative performance. To enable fast design and optimization of this type of evaporators, a correlation model was proposed to calculate the evaporation rate with good prediction performance. The usefulness of this device was demonstrated by performing a two-step continuous-flow synthesis of 4-aminoacetophenone. The combined experimental and CFD studies demonstrate that this tube-in-tube device can serve as a convenient and efficient tool for continuous solvent exchange, particularly from high- to low-boiling solvents, in continuous-flow synthesis.

Migration and Transformation Mechanism of Toxic Electrolytes During Mechanical Treatment of Spent Lithium-Ion Batteries

Recycling spent lithium-ion batteries (LIBs) has great environmental and economic benefits. However, the potential environmental impacts of toxic electrolytes are always ignored in this process. In this paper, the migration and transformation of the toxic electrolytes including organic solvents and fluorides are studied, in which spent LIBs were mechanically treated to simulate actual operating conditions. Besides, for the convenience of analysis, LIB components were classified into strip-shaped, powdery, and liquor components according to their unique properties. The results indicated that strip-shaped components (shell, Cu/Al foil, and separator) were converted into large/middle particle size products (PSPs), while powdery components (cathode, binder, and anode) were converted into small PSPs by mechanical force. Therein, the obvious transformation and deformation of liquor electrolytes were observed, and the residual products were mainly distributed in plastics, anode, and cathode. In addition, low-boiling organic solvents escaped into air causing fire hazard and adverse health effects, and decomposed products of lithium hexafluorophosphate (LiPF6) posed risk of corrosions and acute toxicity. The findings can provide instructions for preventing from hazardous pollutants in the practical application.

Production of Graphene Stably Dispersible in Ethanol by Microwave Reaction

Graphene is a 2D carbon material with peculiar features such as high electrical conductivity, high thermal conductivity, mechanical stability, and a high ratio between surface and thickness. Applications are continuously growing, and the possibility of dispersing graphene in low-boiling green solvents could reduce its global environmental impact. Pristine graphene can be dispersed in high concentration only in polar aprotic solvents that usually have high boiling points and high toxicity. For this reason, the oxidized form of graphene is always used, as it is easier to disperse and to subsequently reduce to reduced graphene oxide. However, compared to pristine graphene, reduced graphene oxide has more defects and has inferior properties respect to graphene. In this work, the polymerization of (diethyl maleate derivate) on graphene obtained by sonication was performed in a microwave reactor. The obtained material has good stability in ethanol even after a long period of time, therefore, it can be used to deposit graphene by mass production of inks or by casting and easy removal of the solvent. The thermal annealing by heating at 300–400 °C in inert atmosphere allows the removal of the polymer to obtain pristine graphene with a low number of defects.

2D/2D Interface Engineering Promotes Charge Separation of Mo2C/g-C3N4 Nanojunction Photocatalysts for Efficient Photocatalytic Hydrogen Evolution.

The focus of designing and synthesizing composite catalysts with high photocatalytic efficiency is the regulation of nanostructures and optimization of heterojunctions. By increasing the contact area between the catalysts, additional reaction sites can be established and charge carriers can be transferred and reacted faster. Here, two-dimensional (2D) Mo2C is prepared via a novel approach by carbonizing precursors intercalated by low-boiling solvents, and a composite catalyst Mo2C/graphitic carbon nitride (g-C3N4) with 2D to 2D structure optimization was synthesized through the self-assembly of 2D Mo2C and 2D g-C3N4. The hydrogen production rate of the photocatalyst at the optimal ratio is 675.27 μmol g-1 h-1, which further exceeds 2D g-C3N4. It is 5.1 times that of the 7 wt % B/2D Mo2C/g-C3N4 photocatalyst and also 3.5 times that of 0.5 wt % Pt/g-C3N4. The enhanced photocatalytic activity is attributed to the fact that Mo2C as a cocatalyst can rapidly transfer the photogenerated electrons of g-C3N4 to the surface of Mo2C, and the 2D to 2D structure can provide abundant reaction sites for photogenerated electrons to prevent their recombination with holes. This study provides new ideas and techniques for the development of 2D platinum-like cocatalysts and the optimization of nanojunctions.

Production of crude 5-hydroxymethylfurfural from glucose by dual catalysts with functional promoters in low-boiling hybrid solvent

5-Hydroxymethylfurfural (5-HMF) is a value-added versatile platform chemical from renewable biomass resources. In addition to improving the efficiency of catalysts for glucose conversion in reaction media, the product separation and purification represent another significant barrier in large scale production of 5-HMF. In this work, 5-HMF production from carbohydrates using a combination of Lewis and Brønsted acid catalysts was investigated in a low boiling point solvent consisting of ethylene glycol dimethyl ether (GDE) and water, allowing for feasible recycling of catalysts and product separation. High yield (70%) of 5-HMF from glucose is achieved in the presence of reaction additives, isopropanol (IPA) and NaCl, that help to stabilize 5-HMF and promote fructose dehydration, respectively. The results are validated in larger scale (glucose 140 g, reaction volume 2.2 L). To recover product free of the catalysts, the low-boiling polar solvents are evaporated and the crude product containing 80% 5-HMF is recovered by dissolution in a small amount of ethyl acetate (EA) followed by evaporation of EA. This 5-HMF production system offers the advantage of high 5-HMF yield from glucose and the feasibility of product separation.

Boosting the Photovoltaic Performance of Doctor-Bladed Organic Solar Cells Using a Low-Boiling Solvent Additive

Boosting the Photovoltaic Performance of Doctor-Bladed Organic Solar Cells Using a Low-Boiling Solvent Additive

Role of Nanodiamond Grains in the Exfoliation of WS2 Nanosheets and Their Enhanced Hydrogen-Sensing Properties.

Herein, for the first time, a combination of detonation nanodiamond (DND)-tungsten disulfide (WS2) was devised and studied for its selective H2-sensing properties at room temperature. DND-WS2 samples were prepared by a sonication-assisted (van der Waals interaction) liquid-phase exfoliation process in low-boiling solvents with DND as a surfactant. The samples were further hydrothermally treated in an autoclave under high pressure and temperature. The as-prepared samples were separated as two parts named DND-WS2 BH (before hydrothermal) and DND-WS2 AH (after hydrothermal). The exfoliated bilayer to few-layer DND-doped WS2 nanosheets were confirmed by ultraviolet-visible spectra, atomic force microscopy, and transmission electron microscopy studies. It was observed that the DND powder not only acted as a surfactant but also doped and expanded on WS2 nanosheets. The difference between samples BH and AH treatment was further investigated using Raman spectroscopy. The WS2 and DND-WS2 samples on SiO2/Si were fabricated using a sputtered Pd/Ag interdigitated electrode and utilized for H2 gas-sensing measurements. Surprisingly, the DND-WS2 exhibits an ultrahigh sensor response of 72.8% to H2 at 500 ppm when compared to only 9.9% for WS2 alone. Also, the DND-WS2 shows a fast response/recovery time, high selectivity, and stability toward H2 gas. It can be attributed to the correlation of the intergrain phase of DND nanoparticles and WS2 nanosheets, which contributes to the easy transportation of charge carriers when exposed to the air and H2 gas atmosphere. Moreover, it is believed that DND-induced WS2 exfoliation might inspire future synthesis of transition metal dichalcogenides induced by DND in green solvents.

Selective substitution of long-acyl groups into alcohols of kraft lignin over transesterification using ionic liquid

Kraft lignin is a valuable aromatic renewable resource that is discharged in large quantities during the kraft pulping process. In this study, kraft lignin derivatives with improved solubility and thermal properties were prepared by a facile chemical modification of the aliphatic hydroxy (R-OH) group in kraft lignin with various ester groups. Kraft lignin was subjected to homogeneous transesterification with vinyl esters as acyl donors using an ionic liquid as a green solvent and catalyst. The selective introduction of acyl groups into the R-OH group was confirmed by nuclear magnetic resonance (NMR) spectroscopy, and it was estimated that approximately 90% of the R-OH group was converted whereas more than 80% of the aromatic hydroxy (Ar-OH) group was retained. The R-OH-selective introduction of long-chain acyl groups of more than six carbons successfully provided superior solubility in common low-boiling solvents, such as chloroform and tetrahydrofuran, and sufficient heat-meltability to be molded into films by hot-pressing. All the kraft lignin derivatives showed high glass transition temperatures of over 100 °C, indicating their potential to be heat-resistant materials. The kraft lignin derivatives, in which only the R-OH group was acylated, retain their inherently rich Ar-OH groups and thus, can be applied as desirable precursors in a wide range of further chemical treatments for functional polymer materials.

Preparation and characterization of organic soluble polyimides with low dielectric constant containing trifluoromethyl for optoelectronic application

Polyimide (PI) films have excellent comprehensive properties and bright prospects in the next generation of optoelectronic and microelectronic applications. PIs were synthesized by aromatic diamines and alicyclic dianhydrides considered to be the most effective method for preparing polyimides with high light transmittance and low dielectric constant. In order to improve the overall performance of polyimide, the introduction of a large trifluoromethyl group into the main chain is also considered a powerful strategy. In this article a novel diamine containing 6 trifluoromethyl groups has been designed and synthesized by Suzuki reaction. Afterwards, PIs were synthesized with fluorinated aromatic dianhydride and alicyclic dianhydride through a two-step method. The two PIs have excellent solubility: PI-a and PI-b exhibited excellent solubility in common polar solvents. Such as DMF, DMAc, NMP and DMSO at room temperature, and PI-a was soluble in low-boiling solvents such as ethyl acetate, CH2Cl2 and CHCl3 at room temperature. PI-b was soluble in low-boiling solvents acetone and CHCl3 at room temperature, which was rarely seen in other aromatic polyimides. Soluble in common organic solvents, especially low boiling point solvents, made these polymers easy to process and suitable for processing technology in solution. This was an important modification for PIs. They also showed good high temperature resistance: the decomposition temperature (T5%) of two PIs were 520 °C and 475 °C. In addition, the residual rate at 790 °C was 50% and 49% respectively. Two PI films had a very low dielectric constant 2.26 and 2.24, respectively, which was attributed to the hyperbranched structure and strong electron-withdrawing fluorine-containing groups. PI-a and PI-b also had low water absorption of 0.66% and 0.72%, respectively. The transmittance of PI-a and PI-b high transparent films at 450 nm were 74% and 82%, respectively. The significant optical modification was mainly due to the weak electron-accepting alicyclic unit and the large trifluoromethyl electron withdrawing group. This work mainly provided an effective strategy for synthesizing comprehensive excellent performance PIs with high transmittance, excellent solubility, low water absorption, high heat resistance and low dielectric constant.

High-Performance Ru 2 P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

High-Performance Ru ₂ P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

Features of the Growth of p-Quaterphenyl Crystalline Films from Solution Drops on Substrates

The features of the nucleation and growth of p-quaterphenyl crystal films from solution drops on substrates are studied under conditions of slow isothermal evaporation of the solvent. Studies on the influence of temperature factor show the largest crystal films are formed at a temperature of about 45°C. It is found that the use of a high-boiling solvent with a high surface tension (1,2,4-trichlorobenzene) makes it possible to form single-crystal films of a much larger scale than when using a low-boiling solvent with a lower surface tension (toluene). The surface properties of solutions in comparison with pure solvents are investigated and analyzed by the hanging drop method and the sessile drop method.

High-Efficiency Hydrolysis of Thermosetting Polyester Resins into Porous Functional Materials Using Low-Boiling Aqueous Solvents

A new high-efficiency reaction system composed of aqueous ethanol-alkali solution is developed for fast and mild hydrolysis of thermosetting unsaturated polyester resins (TUPRs) into porous functio...

Spray-flame synthesis of LaMO3 (M = Mn, Fe, Co) perovskite nanomaterials: Effect of spray droplet size and esterification on particle size distribution

Perovskite nanomaterials such as LaMnO3, LaFeO3, and LaCoO3 were synthesized in a spray flame from metal nitrates dissolved in combustible liquids. The addition of low-boiling solvents such as 2-ethylhexanoic acid (2-EHA) to the ethanol-based solutions supports the formation of phase-pure particles with unimodal particle-size distribution in the 10-nm range attributed to enhanced evaporation through micro-explosions. Nevertheless, in many cases, a second particle mode with sizes of a few hundred nanometers is formed. In this paper, we investigate two possible reasons for the appearance of large particles. Firstly, we analyze the effect of the oxygen dispersion gas flow applied in the two-fluid nozzle on the droplet size distributions of burning sprays using phase Doppler anemometry. We identified that an increase of the dispersion gas flow significantly decreases the number concentration of large droplets (>30 μm), which causes a significant increase of the BET surface area of as-synthesized LaMnO3 and LaCoO3 with increasing dispersion gas flow from 60 m2/g (5 slm dispersion gas) to 100 m2/g (8 slm). Secondly, the esterification in the mixture of solvents towards ethyl-2-ethylhexanoate, which is associated with the release of water as a byproduct, was analyzed by GC/MS. The ester concentration in the iron-containing solution was found to be up to nine times higher than in cobalt or manganese precursor solutions. Simultaneously, the produced LaFeO3 materials show lower BET surface areas and the increasing dispersion gas flow has a minor effect on this material than on the cobalt and manganese perovskite cases. We attribute this to the fact that water formed during esterification forces the hydrolysis of iron nitrate and the formation of large particles within the droplets.

Solvolysis of Bituminous Coal in Coal- and Petroleum-Derived Commercial Solvents.

The solvolytic conversion of softening bituminous coal at 380 °C in solvents derived from the commercial hydrocarbon byproducts and residues from coal and petroleum processing was studied. Hydrogen-donor tetrahydronaphthalene (THN) and nondonor 1-methylnaphthalene (MN) were also used for comparison. The high-boiling solvents of different chemical classes (highly aromatic coal tar, its anthracene fraction, and low-aromatic heavy gas oil of catalytic cracking of the oil residue) and the H-donor THN solvent were found to exhibit high efficiency for coal conversion into quinoline-soluble products. The chemical and molecular compositions of coal, solvents, and dissolved products were characterized in detail by different techniques, including chemical analysis, group analysis, infrared Fourier transform (IRFT) spectroscopy, X-ray diffraction (XRD), liquid chromatography, and thermal analysis to reveal the chemical transformations of the coal–solvent mixture during the dissolution reaction. The solvolysis of coal in the liquid phase of both highly aromatic and low-aromatic solvents was found to involve selective depolymerization of polymer-like coal via breaking of weak linkages between the aromatic units, resulting in the formation of soluble pitchlike products. The effective dissolution of coal in the H-donor THN solvent resulted probably from a combination of the nonselective thermal fragmentation of the coal structure to smaller radical intermediates and their stabilization by hydrogen from THN, producing mainly tar and a few gases. The low-boiling solvents of both predominantly aromatic and aliphatic classes (gas oils from naphtha pyrolysis and delayed coking of the petroleum residue) and MN exhibited poor efficiency for coal dissolution. The concentrations of carcinogenic benzo(a)pyrene (BaP) in the solvents used and in the toluene fractions of the resulting extracts were analyzed. The remarkable result was that coal extracts, compared to solvents, contained much less BaP, probably due to its conversion with coal and/or solvent molecules during coal dissolution.