Lewis Acidic Ionic Liquid Research Articles

Bismuth-rich bimetallic clusters (CuBi8)3+ and [MBi10]4+ (M = Pd, Pt) from ionothermal synthesis

Abstract The reaction of Bi, BiBr3, and CuBr in the Lewis-acidic ionic liquid [BMIm]Br·4AlBr3 (BMIm = 1-n-butyl-3-limidazolium) at 180 °C yielded air-sensitive, shiny black crystals of (CuBi8)[AlBr4]2[Al2Br7]. Crystals of [MBi10][AlCl4]4 (M = Pd, Pt) were obtained by reacting Bi, BiCl3, and MCl2 under similar conditions. The structures have been determined by X-ray diffraction on single-crystals and were found to be very similar to that of the known analogues with other halogens, although not isostructural. In crystals of the complex salts, polyhedral bimetallic clusters (CuBi8)3+ or [MBi10]4+ are embedded in matrices of halogenidoaluminate anions. The heteroatomic nido-cluster (CuBi8)3+ consists of a (Bi8)2+ square antiprism η4-coordinating a copper(I) cation. In the cluster cation [MBi10]4+, the metal atoms M center a pentagonal antiprism of bismuth atoms.

Cost-Effective Processing of Carbon-Rich Materials in Ionic Liquids: An Expeditious Approach to Biofuels.

This work presents a cost-effective approach for processing of renewable carbon-rich biomass using pyridinium-based Lewis acidic ionic liquids (LAILs). Rice husk as carbon-rich lignocellulosic waste was pretreated with a series of neutral and Lewis acidic ionic liquids to yield valuable intermediate platform monosaccharides. Novelty in the work lies in direct conversion of lignocellulosic carbohydrates into reducing sugars without their further conversion into 5-hydroxymethylfurfural or any other platform chemicals that are fermentation inhibitors for bioethanol production. The unconverted cellulose-rich material (CRM) is regenerated as a delignified material by the simultaneous addition of antisolvents. CRM and recovered lignin obtained after pretreatment were analyzed via scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. The process was optimized with respect to a high yield of platform sugars and the quantity as well as quality of recovered CRM and lignin contents. Various reaction parameters involving the molecular structure of ionic liquids (ILs), Lewis acidic strength of ILs, biomass loading into IL, time, temperature, and biomass particle size were screened thoroughly. From all of the tested ILs, unsymmetrical 3-methylpyridinium IL having N-octyl substitution and chloroaluminate anion showed a greater conversion efficiency at 100 °C for 1.5 h. FTIR and SEM analyses of recovered CRM justify >90% lignin removal from rice husk. From all of the removed lignin, 60 wt % of original lignin content was recovered. The Lewis acidic system possessed recycling ability up to 3 times for subsequent treatment of rice husk without a significant loss of efficiency.

Electrochemical Complexation of Polyatomic Aluminum Cations in Quinone-Type Organic Battery Electrodes Revealed By Solid-State NMR

Rechargeable aluminum batteries represent a significant area of opportunity for beyond-lithium-ion energy storage due to the high theoretical capacity (2980 mA∙h∙g-1, 8046 mA∙h∙mL-1), large earth abundance (8.23 wt.%), low cost, and safety of aluminum metal. Due to the stable native oxide layer that forms on aluminum, very few electrolytes are able to reversibly plate and strip aluminum at room temperature. Lewis acidic chloroaluminate ionic liquid electrolytes have demonstrated success in this regard; however, any cathode materials must also be (electro)chemical stable in this electrolyte. Electrode materials based on organic molecules have garnered attention due to their tunable structures and properties, enabling optimization for specific energy storage systems. Furthermore, diverse functional groups enable a range of possible charge storage mechanisms, many of which have yet to be explored in these systems. Like aluminum, organic materials are highly abundant and can be derived from various sources without geopolitical constraints. However, few Al-organic battery studies exist, and none so far have performed mechanistic analyses based on experimental data to identify conclusively the electroactive ions and their binding sites.Here, we present a rigorous analysis of charge storage mechanisms in quinone-type organic molecules for the first time, established through multi-dimensional solid-state nuclear magnetic resonance (ssNMR) spectroscopy in concert with quantum chemical calculations and electrochemical measurements. Indanthrone quinone (INDQ) is investigated for the first time as a model system due to its two distinct quinone functionalities and low solubility in many solvents. Through-space 27Al{1H} and 13C{1H} dipolar-mediated ssNMR techniques are used to establish the sub-nanometer proximities between polyatomic aluminum cations and specific moieties in the organic frameworks. Furthermore, dipolar-mediated ssNMR measurements are sensitive to both molecular dynamics and internuclear distances, which enables us to selectively filter out signals from residual liquid electrolyte, eliminating the need for solvent rinsing that can perturb the sample. Al-INDQ cells achieve reversible capacities of up to 240 mA∙h∙g-1 and maintain capacities >100 mA∙h∙g-1 at rates up to 2400 mA∙g-1. The enolization reaction and charge-balancing AlCl2 + cation complexation was established via dipolar-mediated ssNMR, findings that are corroborated through density functional theory (DFT) calculations. Other quinone-based organic structures with modified structures and compositions were also investigated using similar methods and will briefly be compared to INDQ. In aggregate, the quinone-based model systems serve as a basis to better understand how different functional groups, heteroatoms, and organic structures affect the electrochemical properties of rechargeable Al-organic batteries. The results yield strategies towards creating ‘designer’ organic electrode materials for rechargeable aluminum batteries.

High-efficient esterification of rosin and glycerol catalyzed by novel rare earth Lewis acidic ionic liquid: Reaction development and mechanistic study

BackgroundAs one of the most important modified products of rosin, rosin glyceride was widely used in many aspects. However, the preparation of rosin glyceride is always unfriendly due to the use of liquid catalyst, such as H2SO4 and H3PO4. MethodsThe rosin glyceride with low acid value was synthesized in vacuum conditions using a novel Lewis acidic ionic liquid 1–butyl–3–methylimidazolium chloroscandinate[BuMeim][Sc2Cl7] as catalyst. The [BuMeim][Sc2Cl7] is of excellent catalytic activity and stability. The efficient catalytic activity was studied via the combined Density Functional Theory (DFT) and experimental conditions. Significant findingsThe DFT proved the free energy of the esterification could reach to 31.6 Kcal/mol, which illuminates that the excellent coordination of the anions and cations in the [BuMeim][Sc2Cl7] greatly reduces the reaction energy barrier and promotes the efficient progress of the reaction. As a result, [BuMeim][Sc2Cl7] is a good catalyst for the esterification of rosin and glycerol to prepare rosin glyceride. Furthermore, [BuMeim][Sc2Cl7] could be a potential catalysts for the other esterification.

A comprehensive review on catalytic O-alkylation of phenol and hydroquinone

ABSTRACT The alkylation process involves two competitive paths of O- and C-alkylation and achieving better selectivity for desired products is a very challenging problem. The development of new process for synthesis of O-methylated products of phenol and dihydric phenols is a subject of high industrial and academic interest. Alkyl phenyl ethers, especially anisole and 4-methoxyphenol, have captivated significant interest due to their increasing applications in pharmaceutical industries. The main emphasis of the present review is to explore the recent development in two catalytic O-alkylation processes. The first process is O-methylation of phenol into anisole and another is selective mono O-methylation of hydroquinone into 4-methoxyphenol. The present article covers O-alkylation methods with methanol and dimethyl carbonate as alkylating agent over various acidic and basic catalytic systems. The catalyst systems analyzed involves Bronsted and Lewis acidic and basic ionic liquids, conventional acids, metal oxides, solid acid and basic catalysts, hydrotalcites, various zeolites and heteropolyacids. The mechanistic behavior of alkylation reactions in presence of different catalytic system is reviewed critically which is important to design new and/or modified catalyst in order to maximize the yield of desired product. Additionally, an influence of reaction parameters, role of catalyst and their active sites on product distribution is described. The review paper gives useful insight for researchers in the field of catalysis and reaction engineering of alkylation reactions. Understandings of the reaction pathways will help in developing reliable kinetic models necessary for process scale-up to industrial scale reactor system.

Salts of octabismuth(2+) polycations crystallized from Lewis-acidic ionic liquids

Abstract The reaction of Bi and BiCl3 with RbCl or CsCl in the Lewis-acidic ionic liquid (IL) [BMIm]Cl·4AlCl3 at T = 200 °C yielded air-sensitive, shiny black crystals. X-ray diffraction on single crystals revealed the hexagonal structures of two new salts (Bi8)M[AlCl4]3 (M = Rb, Cs), which are isostructural to the high-temperature form of (Bi8)Tl[AlCl4]3. The known (Bi8)2+ polycation is a square antiprism and can be interpreted as an arachno cluster following modified Wade rules. The crystal structure is a complex variant of the hexagonal perovskite structure type ABX 3 with A = (Bi8)2+, B = M + and X = [AlCl4]–. Chiral strands ∞ { M [ AlCl 4 ] 3 } 2 − ∞ 1 $\infty {}_{\infty }{}^{1}{\left\{M{\left[{\text{AlCl}}_{4}\right]}_{3}\right\}}^{2-}$ (M = Rb, Cs) run along [001]. The (Bi8)2+ polycations are only weakly coordinated inside a cage of 24 chloride ions and show dynamic rotational disorder at room temperature. Upon slow cooling to 170 K, the reorientation of the clusters was frozen, yet no long-range order was established.

Fundamental Investigations of Factors Affecting Electrical and Transport Properties of Lewis Acidic Chloroaluminate Ionic Liquids for Application in Aluminum Ion Battery

High-performance electrochemical energy storage systems are considered key technologies to sustainable energy economy transition. Despite being one of the most mature and leading-edge battery systems, the future of lithium-ion batteries is shadowed by issues related to resource availability, high production cost, and short lifetime. For these reasons, there has been a great impetus towards the development of alternative battery technologies based on abundant and low-cost materials. Among all, aluminum-ion batteries (AIBs) are particularly promising due to high theoretical capacity, low-cost, and ease of handling and storing of metallic aluminum in ambient conditions.The majority of advanced AIB systems utilizes Lewis acidic chloroaluminate ionic liquid (IL) electrolytes, formed by combining molar excess amount of aluminum chloride (AlCl3) with an organic chloride (RCl; R: organic group). In these systems, the chloroaluminate IL electrolyte behaves as (i) a medium for ion transportation and (ii) an electroactive liquid anode material (also known as anolyte) in AIBs. Among various parameters, the AlCl3/RCl molar ratio (r) and the RCl utilized, are considered the most deterministic factors that affect the performance of AIBs. Several battery and electrolyte performance metrics including achievable specific/volumetric cell-level capacity, electrochemical stability window (ESW), ion transport properties, and conductivity, are known to be dependent on r and the RCl utilized. Despite the importance of chloroaluminate ILs in AIB research field, there is a significant lack of fundamental understandings of the effects of r and RCl on these performance matrices. The elucidation of these effects can provide fundamental insights into approaches for optimizing battery operating conditions as well as revealing important characteristics of high-performance chloroaluminate ILs.This work is focused on investigating the effects of r on the electrical and transport properties of four AlCl3-RCl ILs, where RCl includes EMIMCl (1-ethyl-3-methylimidazolium chloride), BMIMCl (1-buthyl-3-methylimidazolium chloride), TMAHCl (trimethylamine hydrochloride), and TEAHCl (triethylamine hydrochloride). A combined experimental-computational approach is utilized to obtain fundamental insights into the influence of AlCl3/RCl molar ratio on various properties of chloroaluminate ILs including ESW, ion transference number, and ionic conductivity.Our results show that the ESW of Lewis acidic chloroaluminate ILs is strongly dependent on r, as r preliminarily governs the concentration of electroactive anionic species (AlCl4 − and Al2Cl7 −) involved in electrochemical redox reactions. For Lewis acidic chloroaluminate ILs, the reduction of Al2Cl7 − to Al (4Al2Cl7 − + 3e− = Al + 7AlCl4 −) sets the cathodic limit while the oxidation of AlCl4 − to evolve Cl2 (2AlCl4 − = Al2Cl7 − + 1/2Cl2 + e−) defines the anodic limit. The cathodic limiting potential shifts positively while the anodic limiting potential shifts negatively, leading to a narrower ESW width with increasing r. Moreover, electrostatic and van der Waals forces significantly affect the cathodic and anodic limiting potentials as these interactions affect the activity of electroactive species involved. The viscosity of chloroaluminate ILs is particularly useful as it reflects the overall degree of interactions in chloroaluminate ILs. Chloroaluminate IL systems that have higher viscosities exhibit a positive shift of anodic and cathodic limiting potentials. The organic cation R+ is determined to contribute substantially to the total ionic conduction in Lewis acidic chloroaluminate ILs. To fundamentally enhance the electrochemical performance of AIBs employing chloroaluminate ILs, strategies focused on the localization of organic cations should be emphasized as they can effectively improve the proportion of ionic conduction by electroactive chloroaluminate anions while hindering the formation of cation-anion aggregates.

Effect of molecular structure of cation and anions of ionic liquids and co-solvents on selectivity of 5-hydroxymethylfurfural from sugars, cellulose and real biomass

The concept of biorefinery still requires advancements in process development for energy and materials. Ionic liquids have been successfully used for several biorefinery applications including high yield synthesis of biofuels and value added platform chemicals. Designing suitable ionic liquid that is efficient in terms of cost as well as product selectivity is still highly needed. This study is carried out to check the effect of different anions of Bronsted acidic ionic liquids (BAILs), Bronsted Lewis acidic ionic liquids (BLAILs), Lewis acidic ionic liquids (LAILs) as well as organic electrolyte solutions (OES) for 5-HMF selectivities from monosaccharides, polysaccharides as well as lignocellulosic composite. Different variables and parameters such as Lewis acidity of anions, alkyl side chain of ionic liquid, metal chloride type and loading, time, temperature, substrate loading, polar protic and aprotic solvents are thoroughly studied for process optimization. Polar protic solvents added in [C1C4SO3HPy] based ionic liquids with CH3COO− and Cl− anions yielded 94 and 80% 5-HMF from fructose and glucose respectively in the presence of AlCl3 as Lewis acid. C4SO3H side chain yielding high from fructose and glucose is inefficient for conversion of cellulose and lignocellulose. High product selectivity from these biopolymers is achieved using butyl side chain with 3-methylpyridinium cation and chlorochromate anion.

Anodic Dissolution of Copper in the Acidic and Basic Aluminum Chloride 1-Ethyl-3-methylimidazolium Chloride Ionic Liquid

The anodic dissolution of copper was investigated at a copper RDE in the Lewis acidic and basic composition regions of the room-temperature AlCl3-EtMeImCl ionic liquid (IL) to assess the utility of chloroaluminate liquids as solvents for the electrochemical machining and electropolishing of copper. In the Lewis acidic IL (60 mol % AlCl3), the dissolution of Cu0 proceeds under mixed kinetic-mass transport control with an exchange current density of 7.00 mA cm−2 at 306 K and an apparent activation free energy of 19.7 kJ mol−1. A formal potential of 0.843 V was obtained for the Cu+/Cu0 reaction from potentiometric measurements. In the basic IL (< 50 mol % AlCl3), potentiometric measurements showed that the oxidation of Cu0 resulted in the formation of [CuCl2]−. In this case, the formal potential of the [CuCl2]−/Cu0 reaction is −0.412 V. At small positive overpotentials, the reaction exhibited mixed control and was first order in the chloride concentration, indicating that only a single Cl− is involved in the RDS. However, at more positive overpotentials, the reaction transitions to mass transport control, and a well-defined limiting current is observed for the anodization process. This limiting current scales linearly with the free chloride concentration in the IL.

A green and highly efficient synthesis of 5-hydroxymethylfurfural from monosaccharides using a novel binary ionic liquid mixture

Abstract We reported the development of 5-hydroxymethylfurfural (HMF) synthesis from monosaccharides using a binary ionic liquid as a reaction medium. Bronsted–Lewis acidic ionic liquid (BLAIL) was synthesized from DABCO, 1,4-butane sultone, and AlCl3 under mild conditions. The BLAIL was found to be a suitable catalyst for the synthesis of HMF from monosaccharides in [Emim]Cl as a solvent. Under the optimized conditions, the yields of the HMF from glucose and fructose were 30.5 % and 96.5 %, respectively. The influence of time, temperature, catalytic loading, and substrate on the reaction was systematically investigated. The binary ionic liquid mixture could be reused three times without a noticeable drop in the activity. The isolation of HMF was easily performed through a liquid-liquid extraction method, which could be applied to the industrial process.

Highly Active Trifloaluminate Ionic Liquids as Recyclable Catalysts for Green Oxidation of 2,3,6-Trimethylphenol to Trimethyl-1,4-Benzoquinone

An effective method for the synthesis of 2,3,6-trimethyl-1,4-benzoquinone via the oxidation of 2,3,6-trimethylphenol as the key step in the in the preparation of vitamin E was presented. An aqueous solution of H2O2 was used as the oxidant and Lewis acidic trifloaluminate ionic liquids [emim][OTf]-Al(OTf)3, χAl(OTf)3 = 0.25 or 0.15 as catalysts. Trifloaluminate ionic liquids were synthesised by the simple reaction between 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (triflate) [emim][OTf] and aluminium triflate used in sub-stoichiometric quantities. The influence of the reaction parameters on the reaction course, such as the amount and concentration of the oxidant, the amount of catalyst, the amount and the type of organic solvent, temperature, and the reaction time was investigated. Finally, 2,3,6-trimethyl-1,4-benzoquinone was obtained in high selectivity (99%) and high 2,3,6-trimethylphenol conversion (84%) at 70 °C after 2 h of oxidation using a 4-fold excess of 60% aqueous H2O2 and acetic acid as the solvent. The catalytic performance of trifloaluminate ionic liquids supported on multiwalled carbon nanotubes (loading of active phase: 9.1 wt.%) was also demonstrated. The heterogeneous ionic liquids not only retained their activity compared to the homogenous counterparts, but also proved to be a highly recyclable catalysts.

Aluminium Electrodeposition in Emimcl-AlCl3 ionogels for Improved Aluminium Batteries

Aluminium batteries are promising candidates for the next-generation of energy storage devices, given the natural occurrence of aluminium (third most abundant element) and the intrinsic safety characteristics of the electrolytes used. The specific capacity of an aluminium negative electrode (2980 mAh g-1) is approximately 77% that of lithium (3860 mAh g-1), while its volumetric capacity of 8040 mAh cm-3 far exceeds that of lithium (2060 mAh cm-3), due to its ability to transfer three electrons [1]. Most non-aqueous aluminium batteries utilise electrolytes including inorganic molten salts, deep eutectic solvents, organic solvents and ionic liquids, and operate by the reversible deposition/dissolution of aluminium at the negative electrode and the intercalation of the chloroaluminate ions at the positive electrode.This work studied the electrodeposition of aluminium from the 1-ethyl-3-methylimidazolium tetrachloroaluminate (EMImCl-AlCl3) ionic liquid and its gel form- the ionogel. Ionogels have previously been shown to improve thermal [2] and moisture stability [3]; here, the ionogel was introduced to widen the potential stability window and enable aluminium deposition from lightweight AlCl4 - anions in Lewis neutral ionogels. Generally, aluminium is deposited by the reduction of heavy Al2Cl7 - ions present only in Lewis acidic ionic liquids, which is typically not possible in neutral and basic compositions as the reduction of the organic cation and subsequent ionic liquid decomposition occurs at a higher potential than the reduction of AlCl4 -.Lewis acidic and neutral ionogels of varying degrees of gelation were synthesised with polyethylene oxide and EMImCl-AlCl3. The electrochemical behaviour of the electrolytes was investigated by cyclic voltammetry, and aluminium deposits from the Lewis neutral ionogel were confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The deposition of aluminium from a Lewis neutral EMImCl-AlCl3 ionogel [2] was demonstrated for the first time (Fig. 1) [4], serving as a basis for further investigation into the role of polymer additives in developing improved ionogel and semi-solid state electrolytes for aluminium batteries.[1] G. A. Elia, K. Marquardt, K. Hoeppner, S. Fantini, R. Lin, E. Knipping, W. Peters, J. F. Drillet, S. Passerini and R. Hahn, Adv. Mater., 28, 7564-7579 (2016).[2] S. A. M. Noor, P. M. Bayley, M. Forsyth and D. R. MacFarlane, Electrochim. Acta, 91, 219-226 (2013).[3] X. G. Sun, Y. Fang, X. Jiang, K. Yoshii, T. Tsuda and S. Dai, Chem. Commun., 52, 292-295 (2016).[4] T. Schoetz, O. M. Leung, I. Efimov, C. Zaleski, A. M. Ortega, N. García García, P. Tiemblo Magro and C. Ponce de Leon, J. Electrochem. Soc., 167, 040516 (2020). Figure 1

Sulfur-Carbon Composite Cathodes for Aluminum-Anion Rechargeable Battery with an Inorganic AlCl3–NaCl–KCl Ionic Liquid

Aluminum-anion rechargeable battery (AARB), in which chloroaluminate anions control the cathodic and anodic reactions, has been getting a lot of attention recently, because Al metal has several advantages, such as very high theoretical capacity (2980 mAh g-1, 8046 mAh cm-3), less expensive and mass consumable material, and moderate reactivity in air. It is known that Al metal deposition/stripping reversibly proceeds in Lewis acidic chloroaluminate melts.1 4[Al2Cl7]- + 3e- ⇌ Al + 7[AlCl4]- In general, AARB uses layered sp2 carbon materials as cathode active materials that can cause the following electrochemical reaction.1 nC + [Al anion]- ⇌ C n [Al anion] + e- (Al anion: [AlCl4]- and [Al2Cl7]-)These materials show a favorable coulomb efficiency over 99 % and are available for rapid charge-discharge. But, the charge-discharge capacities are only 60 ~ 90 mAh g-1, if the electrolyte is Lewis acidic organic chloroaluminate ionic liquids (ILs). Although, in the inorganic ones, e.g., AlCl3–NaCl–KCl, the capacities are over ca. 130 mAh g-1,2 it is still disportionate to high capacity of Al metal anode. Therefore, novel high capacity cathode active materials are required to design appealing AARBs. In this study, we have applied the sulfur-carbon composite material (SPEG) synthesized from the mixture of sulfur and polyethylene glycol3 to the cathode active material for AARB. Electrochemical behavior of the SPEG electrodes was examined in an inorganic 61.0-26.0-13.0 mol% AlCl3–NaCl–KCl IL (eutectic point: 366 K).The procedure used for the preparation of SPEG was identical with that described in previous articles.2 SPEG composite electrodes were prepared by pressing the mixtures of x wt% SPEG, 100-x-5 wt% conductive additive (ketjen black (KB) or multi-walled carbon nanotube (MWCNT), and 5 wt% polytetrafluoroethylene (PTFE) onto molybdenum (Mo) plate current collectors. Al metal plates were employed as anodes. After purification of AlCl3, NaCl, and KCl, the inorganic AlCl3–NaCl–KCl IL was obtained by heating the mixture consisting of 61.0 mol% AlCl3, 26.0 mol% NaCl, and 13.0 mol% KCl at 403 K. The final product was clear and colorless. Electrochemical experiments were carried out using a two-electrode type sealed cell set up in an electric furnace with a temperature-control device. The experimental temperature was 393 K. All the procedures are conducted in an Ar gas-filled glove box with O2 and H2O < 1 ppm.Figure 1 shows cyclic voltammograms recorded at Mo and SPEG composite electrodes in the two-electrode type sealed cell with a 61.0-26.0-13.0 mol% AlCl3–NaCl–KCl electrolyte at 393 K. There is no change in current density in the voltammograms at the Mo electrode, implying that Mo electrode is usable for the current collector in AARB. As to the SPEG composite electrodes, a pair of reduction and oxidation waves appeared at ca. 1.05 V and 1.25 V, respectively. However, the shapes of voltammograms depended on the conductive additive species and their weight ratio. In the case of the KB conductive additive, redox waves with the influence of electric double layer capacitance were observed, when the weight ratio was over 45 wt%. It was difficult to see the waves below 45 wt%. Meanwhile, the use of MWCNT was very effective to improve the cathode performance, and clear redox waves appeared at the additive amount of 10 wt%. Given the fact that electrochemical behavior of the sulfur in an organic AlCl3–[C2mim]Cl (1-ethyl-3-methylimidazolium chloride) IL,4 the redox waves observed in Fig. 1 would originate in the following reaction.8[Al2Cl7]- + 6e- + 3S ⇌ Al2S3 + 14[AlCl4]- These results suggest that the SPEG composite electrodes can work as the cathode in AARB. Charge-discharge tests were conducted under various conditions. Favorable rate capability comparable to the layered sp2 carbon materials was recognized.1 Besides, the SPEG electrodes had very high cathode capacities. The SPEG cathode with KB (45 wt%) showed 323 mAh (g-SPEG)-1 at 5000 mA (g-SPEG)-1. If the MWCNT was employed as a conductive additive, the capacity was decreased to 266 mAh (g-SPEG)-1 at 5000 mA (g-SPEG)-1, but the cyclability was stable up to 600 cycles. From these findings, we concluded that SPEG composite electrodes prepared in this research are promising cathodes for AARB.This research was supported by the MIRAI program (grant number JPMJMI17E9), JST. References T. Tsuda, G. R. Stafford, and C. L. Hussey, J. Electrochem. Soc., 164, H5007 (2017) and references therein.C.-Y. Chen, T. Tsuda, S. Kuwabata, and C. L. Hussey, Chem. Commun., 54, 4164 (2018).T. Kojima, H. Ando, N. Takeichi, and H. Senoh, ECS Trans., 75, 201 (2017).T. Gao, X. Li, X. Wang, A. J. Pearse, K. J. Gaskell, et al., Angew. Chem. Int. Ed., 55, 9898 (2016). Figure 1

Glycolysis of poly(ethylene terephthalate) waste catalyzed by mixed Lewis acidic ionic liquids

Widely used poly(ethylene terephthalate) (PET) material induces environmental concern on its wastes. In this paper, different 1-hexyl-3-methylimidazolium (Hmim) halometallates, including [Hmim]ZnCl3, [Hmim]CoCl3, [Hmim]FeCl4 and [Hmim]CuCl3, are synthesized as Lewis acidic ionic liquids (LAIL) catalysts for PET degradation in excess ethylene glycol (EG). By using individual or mixed LAIL catalysts, product bis(hydroxyethyl) terephthalate (BHET) is characterized by FT-IR, 1H-NMR and DSC et al. From the PET conversion and yield of BHET product, a synergistic effect is found in mixed [Hmim]ZnCl3 and [Hmim]CoCl3 complexes. 87.1% BHET from original PET wastes catalyzed by equimolar [Hmim]ZnCl3 and [Hmim]CoCl3 mixture is higher than any individual IL halometallate. The filter residues after removing the BHET products with different reacting time using [Hmim]ZnCl3 and [Hmim]CoCl3 as catalyst, respectively, are characterized by 1H-NMR. The area ratio of the methylene protons of COO–CH2 (δ = 4.30 ppm) and the aromatic protons of the benzene ring (δ = 8.12 ppm) of filter residues suggests that more by-products will be produced by [Hmim]ZnCl3 because of its relatively higher catalytic activity in the chain scission stage. The glycolysis synergy comes from the balance between high reactivity of [Hmim]ZnCl3 and high selectivity of [Hmim]CoCl3.

Electroanalytical Study of Active Species to Deposit Ti Alloy from 1-Butyl-3-Methylimidazolium Chloride-Aluminum Chloride Ionic Liquid

Understanding the electrochemical deposition of titanium and its alloy from the ionic liquid electrolyte is technologically very essential and necessitates a wide range of attention to gain more insights into their electrochemistry. In this work, the electrochemical behavior of titanium-chloroaluminate anion species in the Lewis acidic alkyl imidazolium-chloroaluminate ionic liquid electrolyte is investigated by electroanalytical techniques such as cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP). The effect of scan rate on peak potential and peak current, constant current density, constant applied potential, and the electrolyte temperature are discussed. It is shown that the redox reaction of the Ti(II)/Ti(0) deposition from titanium hepta-chloroaluminate ([Ti(Al2Cl7)4]2−) anions is a quasi-reversible process with a 2-electron transfer reaction while that of Al(III)/Al(0) deposition from hepta-chloroaluminate ([Al2Cl7]−) anions proceeds through 3-electron transfer. The cyclic voltammograms indicated that the reduction of [Al2Cl7]− and [Ti(Al2Cl7)4]2− species to corresponding aluminum and titanium forms is a diffusion-controlled phenomenon. The diffusion coefficients of the titanium hepta-chloroaluminate anion are determined under the studied experimental conditions at different temperatures using CV and CP techniques.

Conductivity of 1-Ethyl-3-Methylimidazolium Chloride (EMIC) and Aluminum Chloride (AlCl3) Ionic Liquids at Different Temperatures and AlCl3 Mole Fractions

In this work, the conductivity (k) of Lewis acidic ionic liquid (IL) comprising a melt of organic chloride and aluminum chloride (AlCl3) with different molar ratios of organic chlorides with AlCl3 in the temperature range of 70-110 °C are reported. The ILs prepared with three imidazolium-based organic chlorides such as EMIC, BMIC, and HMIC are studied. The molar ratios of 1:1.5, 1:1.8, and 1:2.0 are selected for the study to maintain the acidity of the ILs for possible metal electrodeposition applications. The electrochemical behavior of anion species in the three ILs is studied using electrochemical impedance spectroscopy (EIS) technique and obtained the precise and fast measurement of conductivity values. The measured k values of all the ILs followed the Arrhenius law. The activation energies of conduction determined by fitting the experimental conductivity data are in good agreement with the literature. The conductivity of ILs with lower alkyl group organic chlorides decreased with the higher mole fraction of AlCl3. In contrast, the conductivity of IL having a higher alkyl group organic chloride (HMIC) increased with the increasing mole fraction of AlCl3. Based on the thermodynamic calculations, the differences in conductivities are attributed to the anion concentration, the molecular structure, cation-anion interactions, and hydrogen bonds in the ILs.

Facile Synthesis of 2‐Amino‐4,6‐dimethoxypyrimidine over Lewis Acidic Ionic Liquid Catalysts

Abstract2‐amino‐4,6‐dimethoxypyrimidine (ADMP) is an important intermediate for the synthesis of sulfonylurea herbicides. As the most critical step in the ADMP synthesis, ADMP prepared by cyclization of 3‐amino‐3‐methoxy‐N‐cyano‐2‐propaneamidine (AMCP) are rarely reported, especially its reaction mechanism. Here, a Lewis acidic ionic liquid catalyst was firstly introduced to increase reaction rate. The Et3NHCl‐2ZnCl2 catalyst possesses excellent catalytic performance and good stability. The yield of ADMP can reach up to 94.8% under 50 °C for 3 h. And the catalytic mechanism was studied. The anion of Et3NHCl‐2ZnCl2 is conducive to ring formation, and the cation is conducive to hydrogen transfer during rearrangement. The stronger Lewis acidity of the catalyst is conducive to cyclization. This work firstly introduces Lewis acidic ionic liquids into the process of AMCP catalytic cyclization to ADMP, which can open novel vistas for the more economically and faster preparation for ADMP.

Novel Brønsted–Lewis acidic di-cationic ionic liquid for efficient conversion carbohydrate to platform compound

A series of Bronsted–Lewis acidic di-cationic ionic liquids (BLAILs) were synthesized and the catalytic properties of glucose conversion to 5-hydroxymethylfurfural (5-HMF) were investigated. The experimental results showed that the ionic liquid with aluminum trichloride as Lewis acid anion (BLAIL-5) exhibited good catalytic performance. Under the best reaction conditions, the yield of the glucose conversion into 5-HMF and 5-EMF were 71% and 66%, respectively. In addition, the yield of cellulose to 5-HMF is 41%. The optimized catalytic system could be reused for 5 times without significant catalytic performance loss. In addition, the mechanism of BLAIL-5 promoting glucose conversion to 5-HMF was studied by density functional theory calculation (DFT).

Anodic Dissolution of Copper in the Aluminum Chloride-1-Ethyl-3-Methylimidazolium Chloride Ionic Liquid

The ever popular AlCl3-1-ethyl-3-ethylimidazolium chloride (EtMeImCl) ionic liquid (IL) system offers a unique solvation environment for many metal ions. In fact, the use of these chloroaluminate ionic liquids for the electrochemical surface finishing of metals was recently reviewed.1 These ionic liquids display adjustable Lewis acidity that depends directly on the mole ratio of the AlCl3 to the organic salt. The basic AlCl3-EtMeImCl mixture, which contains coordinately unsaturated Cl-, provides a solvation environment similar to aqueous HCl and NaCl, except of course without the complications due to the H2O solvent or H3O+. The opposite situation prevails in the Lewis acidic ionic liquid because the main chemically active ionic component of the ionic liquid is the coordinately unsaturated species, [Al2Cl7]-. Thus, there are no “hard” ligands available to form stable, isolable anionic complexes with the anodization product. Recently, both composition regions of the AlCl3-EtMeImCl IL system have been explored for the electrodissolution/electropolishing of Al.2 The advantages afforded by anodic dissolution of metals in this ionic liquid relative the aqueous acids and salt solutions commonly used for this purpose are quite obvious, i.e., the avoidance of the oxide surface films that invariably complicate the metal electropolishing process. In this paper, we report the thermodynamics and kinetics of the anodic dissolution of copper metal in the acidic and basic compositions of the AlCl3-EtMeImCl ionic liquid. In the former, the dissolution of copper at a Cu-RDE exhibits mixed control. No limiting current or passivation due to the formation of an insoluble surface film was apparent. In the basic composition region, mixed control was observed at small overpotentials, but as the overpotential was increased, a limiting current was obtained that scaled linearly with the Cl- concentration in the ionic liquid. The connection between these results and the mechanism of the dissolution process will be discussed.____________________________________________ 1. T. Tsuda, G. R. Stafford and C. L. Hussey, J. Electrochem. Soc., 164, H5007 (2017).2. C. Wang and C. L. Hussey, J. Electrochem. Soc., 163, H1186 (2015).

One-Pot Deconstruction and Conversion of Lignocellulose Into Reducing Sugars by Pyridinium-Based Ionic Liquid-Metal Salt System.

Constantly decreasing fossil resources and exceeding energy demands are the most alarming concerns nowadays. The only way out is to develop efficient, safe, and economical biomass processing protocols that can lead toward biofuels and fine chemicals. This research is one of such consequences involving the deconstruction and conversion of wheat straw carbohydrate constituents into reducing sugars via one-pot reaction promoted by Lewis acidic pyridinium-based ionic liquids (PyILs) mixed with different metal salts (MCl). Various parameters such as the type of metal salt, loading amount of metal salt, time, temperature, particle size of biomass, and water content which affect the deconstruction of wheat straw have been evaluated and optimized. Among the studied ionic liquid (IL) and metal salt systems, the best results were obtained with [BMPy]+. The dinitrosalicylic acid (DNS) assay was used to determine the percentage of total reducing sugars (TRS) generated during treatment of wheat straw. The deconstructed wheat straw was characterized with various analytical tools, that is, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) analyses. The IL–metal salt system was recycled for subsequent treatment of wheat straw. Statistical parameters were calculated from analysis of variance (ANOVA) at the 0.05 level of confidence.