Efficient Homogeneous Catalyst Research Articles

Catalytically Active Site Mapping Realized through Energy Transfer Modeling.

The demands of a sustainable chemical industry are a driving force for the development of heterogeneous catalytic platforms exhibiting facile catalyst recovery, recycling, and resilience to diverse reaction conditions. Homogeneous-to-heterogeneous catalyst transitions can be realized through the integration of efficient homogeneous catalysts within porous matrices. Herein, we offer a versatile approach to understanding how guest distribution and evolution impact the catalytic performance of heterogeneous host-guest catalytic platforms by implementing the resonance energy transfer (RET) concept using fluorescent model systems mimicking the steric constraints of targeted catalysts. Using the RET-based methodology, we mapped condition-dependent guest (re)distribution within a porous support on the example of modular matrices such as metal-organic frameworks (MOFs). Furthermore, we correlate RET results performed on the model systems with the catalytic performance of two MOF-encapsulated catalysts used to promote CO2 hydrogenation and ring-closing metathesis. Guests are incorporated using aperture-opening encapsulation, and catalyst redistribution is not observed under practical reaction conditions, showcasing a pathway to advance catalyst recyclability in the case of host-guest platforms. These studies represent the first generalizable approach for mapping the guest distribution in heterogeneous host-guest catalytic systems, providing a foundation for predicting and tailoring the performance of catalysts integrated into various porous supports.

Catalytically Active Site Mapping Realized through Energy Transfer Modeling

AbstractThe demands of a sustainable chemical industry are a driving force for the development of heterogeneous catalytic platforms exhibiting facile catalyst recovery, recycling, and resilience to diverse reaction conditions. Homogeneous‐to‐heterogeneous catalyst transitions can be realized through the integration of efficient homogeneous catalysts within porous matrices. Herein, we offer a versatile approach to understanding how guest distribution and evolution impact the catalytic performance of heterogeneous host–guest catalytic platforms by implementing the resonance energy transfer (RET) concept using fluorescent model systems mimicking the steric constraints of targeted catalysts. Using the RET‐based methodology, we mapped condition‐dependent guest (re)distribution within a porous support on the example of modular matrices such as metal–organic frameworks (MOFs). Furthermore, we correlate RET results performed on the model systems with the catalytic performance of two MOF‐encapsulated catalysts used to promote CO2 hydrogenation and ring‐closing metathesis. Guests are incorporated using aperture‐opening encapsulation, and catalyst redistribution is not observed under practical reaction conditions, showcasing a pathway to advance catalyst recyclability in the case of host–guest platforms. These studies represent the first generalizable approach for mapping the guest distribution in heterogeneous host–guest catalytic systems, providing a foundation for predicting and tailoring the performance of catalysts integrated into various porous supports.

Facile and convenient electrochemical syntheses of novel multifunctional (catalytic, antioxidant and in vivo antimicrobial) phosphorylated chitosan derivatives

The electrochemical coupling of N-protected chitosan with diphenylphosphine oxide was recognized as new facile, fast, and convenient route to phosphorylated chitosans. The reaction affords low substituted (capable of self-assembling into nanoparticles), moderately substituted (water soluble) or highly substituted (soluble in both water and toluene) polymeric chitosan phosphonates. The degree of substitution can be adjusted by simply increasing the triphenylphosphine oxide/chitosan ratio. Highly substituted polymers (CH-P0.70) are efficient homogeneous catalysts towards the model reaction of monoglyceride synthesis (ca. 100% yield in 3 h). The phosphorylated chitosans are also efficient antioxidants. Their antioxidant effect increases with an increase in their degree of substitution. CH-P0.70 exhibits an antioxidant activity comparable to that of the natural antioxidant ascorbic acid. Remarkably, the highly substituted species is characterized by a strong in vivo antibacterial effect which is even more pronounced than that of the commercial antibiotics ampicillin and gentamicin. Moreover, the obtained phosphorylated chitosan CH-P0.70 demonstrates neither acute nor subacute in vivo toxicity.

Bioinspired octanuclear copper cubane complex as an efficient molecular electrocatalyst for water oxidation

Water oxidation catalysts (WOCs) with excellent activity and stability are highly desired. Numerous efforts have been dedicated to develop WOCs mimicking the cubic structure and activity of Mn4CaO5 cluster in oxygen-evolving center (OEC) of photosynthesis system II (PSII). Herein, a octanuclear Cu cluster [Cu8(dpy{OH}O)8(OAc)4]4+ (1, dpy{OH}O− = the monoanion of the hydrated, gem-diol form of di-2-pyridyl ketone) that contains two Cu4O4 cubic fragments with bioinspired structure mimicking the Mn4CaO5 cluster of OEC of natural PSII is developed as efficient homogeneous catalyst for electrochemical water oxidation under near neutral condition for the first time. It exhibits outstanding water oxidation catalytic activity via accelerating oxygen evolution with onset overpotential of 730 mV and appreciable turnover frequency of 20.1 s−1. Collective experiments together confirmed the homogeneity and stability of cluster 1 under long-term water oxidation catalytic cycle. Kinetic study reveals the water nucleophilic attack (WNA) catalytic mechanism occurs on the coordination unsaturated Cu center of the cluster. This work provides the inspiration of the development of robust bioinspired catalyst for electrochemical water oxidation.

Asymmetric Hydrogenation of Ketones by Simple Alkane-Diyl-Based Ir(P,N,O) Catalysts: A Comparative Study.

The development of new chiral ligands with simple and modular structure represents a challenging direction in the design of efficient homogeneous transition metal catalysts. Herein, we report on the asymmetric hydrogenation of prochiral ketones catalyzed by the iridium complexes of simple alkane-diyl-based P,N,O-type chiral ligands with a highly modular structure. The role of (i) the P-N and N-O backbone in the potentially tridentate ligands, (ii) the number, position and relative configuration of their stereogenic elements and (iii) the effect of their NH and OH subunits on the activity and enantioselectivity of the catalytic reactions are studied. The systematic variation in the ligand structure and the comparative catalytic experiments shed light on different mechanistic aspects of the iridium-catalyzed reaction. The catalysts containing the simple alkane-diyl-based ligands with central chirality provided high enantioselectivities (up to 98% ee) under optimized reaction conditions and proved to be active and selective even at very high substrate concentrations (100 mmol substrate/mL solvent).

A Novel Efficient and Biodegradable Natural Catalyst and Bio Based Solvents for the Green One Pot Three Component Synthesis of Tetrahydrobenzo[B]pyran and 3,4-Dihydropyrano[C]chromenes

This study presents a novel and efficient method for synthesizing Tetrahydrobenzo[b]pyran and 3,4-Dihydropyrano[c]chromene derivatives using honey as a highly efficient homogeneous catalyst. Through a one-pot three-component condensation of aromatic aldehydes with malononitrile and dimedone or 4-hydroxycoumarin, excellent yields were achieved under environmentally friendly conditions. The utilization of honey, a non-toxic and biodegradable catalyst, underscores the method's significance in green chemistry. The abstract highlights the method's advantages, including high yields, short reaction times, simple work-up, and its potential for applications in the green pharmaceutical and chemical industries. Additionally, the intricate role of honey as a catalyst in chemical reactions is explored, shedding light on its mechanism and potential applications in organic synthesis and other chemical processes. This research introduces a promising and environmentally friendly approach for the green synthesis of biologically active heterocyclic compounds using a natural, biodegradable catalyst, contributing significantly to the advancement of green chemistry practices.

Fe (III)–porphyrin complex as an efficient and recyclable homogeneous catalyst for the synthesis of pyrano thiazole 6-carbonitrile derivatives in aqueous medium

In this study, the Fe(III)–porphyrin complex (FePOphy complex) was successfully utilized as an efficient and recyclable catalyst for a one-pot, three-component reaction involving aromatic aldehydes, 2,4-thiazolidenedione, and malononitrile. This reaction led to the synthesis of pyrano thiazole 6-carbonitrile derivatives under environmentally friendly conditions. The structures of the formed compounds were determined through elemental and spectral analyses including infrared (IR, 1H NMR and 13C NMR, CHN and mass spectrometry, confirming the successful synthesis of the desired products. The reactions were conducted in a compassionate environment using a green solvent (H2O/EtOH). The outcomes demonstrated the excellent catalytic activity and selectivity of the complexes, which led to good yields of the intended products. As a result, the study offers useful information on the FePOphy complex’ synthetic uses, and the creation of effective and environmentally acceptable catalysts, and emphasizes their potential as powerful catalysts for a variety of organic transformations. This strategy’s simplicity, safety, commercially accessible catalyst, stability, fast reaction time, and outstanding yields may be used in the industry in the future.

Green synthesis of lichenan-decorated silver nanoparticles for catalytic hydrogenation of organic dyes and bacterial disinfection

Developing an eco-friendly and efficient homogeneous catalyst for treating complex wastewater containing toxic organic pollutants and bacteria is in significant demand. Herein, ultra-small Ag nanoparticles (NPs)-loaded random coil lichenan nanocomposite (L-AgNP) was prepared through a low-cost and green one-step in-situ reduction strategy using lichenan as the reducing agent. The random coil of lichenan acted as a micro-reactor to disperse and stabilize AgNPs via the Ag-O bonding interaction. In the participation of NaBH4, L-AgNP nanocomposite could achieve greater catalytic efficiency for catalyzing reduction of 4-nitrophenol (∼120 s, 34.34 × 10−3 s−1) with the smaller size of AgNPs or the higher content of Ag. The nanocatalyst also exhibited outstanding catalytic efficiency for congo red, rhodamine B, methylene blue, and methyl orange. The L-AgNP could be easily recycled through ethanol precipitation and continuously reused for ten cycles with a tiny loss of conversion rate. Furthermore, L-AgNP also displayed favorable antibacterial activity, inhibiting the growth of Escherichia coli and Staphylococcus aureus with more than 98 % disinfection ratio. This work provides a green strategy to develop polysaccharide-based multifunctional homogeneous catalysts focusing on wastewater purification.

N−SO3H Functionalised Brønsted Acidic Ionic Liquid Catalysed Sequential One‐Pot Synthesis of 2‐Amino‐3‐Cyanopyridines via Claisen‐Schmidt Condensation Under Solvent‐free Condition

AbstractThis work presents a simple approach for the synthesis of 2‐amino‐3‐cyanopyridines via a one pot two‐step sequential route catalysed by direct N‐−SO3H functionalised Brønsted acidic ionic liquids (BAILs). Herein, catalytic activities of four BAILs namely ([TSPi][Cl]2, [DSIM][TFA], [EDSIM][TFA] and [DBDSA][TFA]) were explored and among them [TSPi][Cl]2 was found to be the most efficient reusable homogeneous catalyst. This process involves the ionic liquid catalysed in situ generation of chalcones from Claisen‐Schmidt condensation between aromatic aldehydes and acetophenone/4‐Cl acetophenone, followed by multicomponent reaction (MCR) with malononitrile and ammonium acetate using the same IL catalyst to selectively produce 2‐amino‐3‐cyanopyridine derivatives in a solvent‐free medium at 80 °C within 30–60 minutes in high yields (96–86 %). This amalgamation of MCR with ionic liquids and solvent‐free conditions makes the present work more compliant with the protocols of Green Chemistry.

Cobalt(III)–porphyrin Complex as an Efficient and Recyclable Homogeneous Catalyst for the Synthesis of Tetrahydro-2-oxa-4-thia-diazapentalen-5-one Derivatives in Aqueous Medium

Abstract: In this study, we successfully synthesized the CoPHrn complex as an efficient and recyclable catalyst for the one-pot, three-component reaction of aromatic aldehydes, 2,4-thiazolidenedione, and hydroxylamine hydrochloride, leading to the synthesis of tetrahydro- 2-oxa-4-thia-diazapentalen-5-one derivatives under environmentally friendly conditions. The structures of the newly formed compounds were determined through elemental and spectral analyses. This methodology offers significant advantages, including its ecofriendliness, cost-effectiveness, operational simplicity, extensive reusability, and applicability, as well as the easy recovery of the catalyst using straightforward methods. Additionally, a series of tetrahydro-2-oxa-4-thia-diazapentalen-5-one derivatives were successfully synthesized. Notably, this novel procedure demonstrates remarkable benefits in terms of safety, simplicity, stability, mild reaction conditions, short reaction times, excellent yields, and high purity, all achieved without the use of hazardous solvents.

Synthesis of Bifunctional Catalysts for the Cycloaddition of CO2 to Epoxides through an Epoxide‐Driven Strategy

AbstractThe design of molecular scaffolds bearing multiple functional groups for the activation and ring‐opening of epoxides is a crucial challenge for the synthesis of efficient homogeneous and heterogeneous catalysts that are used for the cycloaddition reaction of CO2 to epoxides. Traditional approaches to prepare such multifunctional catalysts often imply multistep synthetic procedures and expensive building blocks. In this work we show that bifunctional catalysts for the cycloaddition of CO2 to epoxides bearing a Lewis acid metal and a quaternary ammonium halide group can be prepared in just two steps starting from an opportunely designed epoxide precursor by using inexpensive substrates. Such a readily accessible catalyst was applied for the cycloaddition of CO2 to a series of epoxides under atmospheric conditions generally leading to quantitative substrate conversion and high carbonate selectivities. Importantly, we also show that the epoxide‐driven concept developed for the preparation of the molecular catalyst, could be applied to prepare recyclable heterogeneous systems for the target cycloaddition reaction.

Single crystal structure features of a new Cu (II) coordination polymer as an efficient homogeneous catalyst in the selective conversion of sulfides

This study reports the synthesis of a new coordination polymer of Cu (II) formulated as [Cu (Tu)3]n[Cu(Tu)3]·2(pzdc) (1) where tu = thiourea, and (pzdc)2− = 2,3-pyrazinedicarboxylate. Complex 1 was characterized by elemental analysis (CHN), Fourier transformed-infrared (FT-IR) spectroscopy, energy-dispersive X-ray spectroscopy (EDXS or EDS), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The molecular structure of complex 1 has been confirmed by single-crystal X-ray diffraction (SC-XRD). The SC-XRD results show that complex 1 crystallized in a monoclinic crystal system with space group P21/c and metal centers Cu1 and Cu2 adopted slightly distorted tetrahedral and triangular geometry, respectively. The molecular structure of complex 1 is stabilized by a dense network of hydrogen bonds such as NH⋯O, besides electrostatic attraction. Complex 1 was used as a catalyst for the selective oxidation of thioanisole and a number of sulfides to the corresponding sulfoxides or sulfones with high conversion and high selectivity in the presence of hydrogen peroxide as a green oxidant. The results showed that complex 1 accelerates the conversion of sulfides. The influence of varying parameters such as catalyst dosage, temperature, solvent, and H2O2/substrate molar ratio were examined in an attempt to optimize the conversion of thioanisole and, in particular, to improve the selectivity of the desired products (sulfoxides). Then, the optimized conditions were used to investigate the generality of catalytic activity of complex 1 to oxidize several other sulfides to its sulfoxide's analogues, that corresponding sulfoxides were obtained with excellent selectivity in most cases (up to 84 %) through high conversion of sulfides (up to 82 %).

TBAB in One-pot Green Approach for the Synthesis of N-Heterocyclic Compounds: A Comprehensive Review

Abstract: Designing innovative one-pot reactions using eco-friendly methodologies has attracted a lot of attention in drug development, organic synthesis, and material sciences due to the impressive art of mitigating the possibility of side reactions, particularly for the synthesis of Ncontaining heterocycles, which are crucial for the manufacturing and development of new drugs. These moieties have demonstrated a diversity of biological applications, such as anti-tumor, antimicrobial, antibiofilm, antioxidant, and anti-inflammatory. Due to the wide range of medicinal applications, several techniques have been reported in the literature for the synthesis of these physiologically important scaffolds, employing different homogeneous and heterogeneous catalysts. One such highly efficient catalyst is tetrabutylammonium bromide (TBAB), which has gained significant attention as an efficient metal-free homogeneous phase-transfer catalyst to facilitate a reaction when the reactants are in different phases. It is also used as a zwitterionic solvent in many organic transformations and as an effective co-catalyst for a variety of coupling reactions. In the current study, we highlighted recent developments in one-pot reactions involving TBAB as a phase-transfer catalyst or zwitterionic solvent for the efficient synthesis of various biologically promising monocyclic and bicyclic N-heterocycle scaffolds.

Sodium Glyceroxide: An Efficient Homogeneous Alkaline Catalyst for Biodiesel Synthesis

Biodiesel is obtained from the alcoholysis of triglycerides and has been used as a renewable alternative to diesel. Though the methanolysis of triglycerides in the presence of MeONa catalyst has been widely used, searching for alternatives that may improve the competitiveness of the production chain is still a challenge. The aim of this work was to evaluate sodium glyceroxide as a catalyst in the methanolysis of soy oil. Sodium glyceroxide was obtained from glycerol and NaOH in ethanol, and characterized by thermogravimetric analysis (TGA), X-ray powder diffraction (XRD) and, Fourier transform infrared (FTIR) spectroscopy. The transesterification reaction was optimized after two sets of experiments based on the Doehlert matrix experimental design. In the first one, the influence of the molar ratio of methanol/triglyceride, and the amount of catalyst (m/m with respect to the triglyceride) were studied. In the second set, the temperature, and the reaction time were studied. The best conditions were found as 12:1 molar ratio, 2% of catalyst, 50 ºC, and 60 min. The conditions were applied in the transesterification of canola and sunflower oils, and tallow. All the biodiesels were obtained with an ester content superior to 98%, free from methanol and triglycerides. Specific mass, viscosity, and pour point were determined and met the international specifications.

Cationic lignin as an efficient and sustainable homogenous catalyst for aqueous Knoevenagel condensation reactions.

Knoevenagel condensation is a chemical reaction between aldehydes and active methylene-containing compounds in the presence of heterogeneous, basic homogenous organic or inorganic catalysts and solvent or neat systems. Herein, we introduced a new strategy for this synthesis by using the aqueous solution of cationic kraft lignin (CKL) as a catalyst. The CKL was synthesized through the reaction of kraft lignin (KL) with glycidyltrimethylammonium chloride (GTMAC) in a basic medium. The optimal reaction conditions for the Knoevenagel reaction were 5% catalyst load (weight of catalyst to the weight of benzaldehyde), water as the solvent, and at room temperature, which generated the products with a yield of 97%, illustrating that the CKL was an effective homogenous and green catalyst. The results confirmed that the increase in CKL charge density improved the product yield. The water-insoluble products were easily separated by filtration, and the filtrate containing the catalysts was reused effectively for 5 cycles without a significant decrease in the production yield, which would confirm the advantages of this catalyst for this reaction system. The CKL catalyst exhibited biodegradability comparable to KL. This paper discusses a novel method for Knoevenagel condensation reactions for different aldehydes in a green system utilizing a sustainable, biodegradable catalyst at room temperature and in an aqueous system.

Accessing 2‐Aryl Quinolines via Acceptorless Dehydrogenation and Transfer Hydrogenation Under Base and Solvent‐Free Reaction Conditions

AbstractCatalytic hydrogenation/dehydrogenation reactions are one of the most active areas of research for the synthesis of pharmaceuticals and fine chemicals. Despite several efficient homogeneous catalysts that have already been identified, highly active heterogeneous catalysts remain elusive. Herein, we report an easy and convenient wet impregnation method for the synthesis of Pd‐nanoclusters supported on ZnO nanoparticles. The catalyst displays a multifunctional role in 2‐aryl quinolines synthesis using alcohol and 2‐nitrobenzyl alcohol as reactants via dehydrogenation/hydrogenation pathway under neat and base‐free reaction conditions. The catalyst exhibits excellent selectivity and can be recycled five times without appreciable loss in its activity.

Tetrabutylammonium bromide/triethanolamine deep eutectic solvents with double hydrogen bond as efficient catalysts for fixation of CO2 in cyclic carbonates under mild conditions

AbstractBACKGROUNDCarbon dioxide is not only a major greenhouse gas but also an important carbon resource, which is abundant, renewable, low cost and non‐toxic. The coupling reaction of CO2 with epoxides has shown great potential in the field of chemical carbon fixation due to its 100% atomic utilization efficiency. Deep eutectic solvents (DESs) based on tetrabutylammonium bromide (TBAB) were evaluated for cycloaddition reaction of CO2 with propylene oxide (PO) to propylene carbonate (PC). Density functional theory (DFT) was used to calculate the catalytic performance of DES in CO2 cycloaddition reaction.RESULTSThe utilization of DES containing triethanolamine (TEA) as hydrogen bond donor significantly shortened the reaction time. Under optimal reaction conditions (30 mmol PO, 5 mol% TBAB/TEA (1:1) DES, 1.0 MPa CO2, 90 °C, 2 h), high PC yield (98%) was obtained. DFT calculations revealed that TBAB/TEA (1:1) DES was used as the catalyst for the coupling reaction between PO and CO2, with the ring‐opening process serving as the rate‐determining step and energy barrier of 17.9 kcal mol−1. TBAB/TEA (1:1) DES exhibited excellent recyclability and could be reused more than five times.CONCLUSIONTBAB/TEA (1:1) DES is a highly efficient homogeneous catalyst for the synthesis of cyclic carbonates through the cycloaddition reaction of CO2 and epoxides. The synergistic catalytic effect of the double hydrogen bonds between DES and Br anions is the reason for its high efficiency. © 2023 Society of Chemical Industry.

Enhanced denitrification of aniline and its derivatives by catalysts, anions, and co-fuels during supercritical water oxidation process

We investigated the denitrification performance of aniline and its derivatives (N-methylaniline and N, N-dimethylaniline) in supercritical water oxidation (SCWO) under varying conditions (temperature: 643–743 K, reaction time: 0.5–4 min, pressure: 24.0 MPa, oxidation coefficient: 300%). Cu2 + proved to be an efficient homogeneous catalyst, generating radicals via a Fenton-like reaction. Isopropyl alcohol (IPA) outperformed methanol and ethanol as a co-fuel, enhancing TN removal due to its higher heating value. Nitrogen-containing product distribution revealed that N2 generation correlated with org-N depletion, especially with Cu2 + and IPA. A denitrification mechanism was elucidated using DFT, with Fukui indices, EHOMO, and ELUMO highlighting aniline's greater susceptibility compared to MA and DMA. Our findings provide insights into optimizing SCWO denitrification using aniline derivatives, shedding light on sustainable nitrogen removal processes.

PolyE-IL Is an Efficient and Recyclable Homogeneous Catalyst for the Synthesis of 5-Hydroxymethyl Furfural in a Green Solvent.

5-Hydroxymethyl furfural (5-HMF) is a potential platform molecule with multidimensional applications and can be produced from biomass-based hexose sugars. In the present article, polyethyleneimine (PEI)-functionalized polymeric Bronsted acid ionic liquid (PolyE-IL) catalyst has been explored for fructose dehydration in the presence of isopropyl alcohol (IPA) as a green and low-boiling-point (LBP) organic solvent. The use of homogeneous PolyE-IL catalyst provides several specific advantages in terms of high yield, conversion, selectivity, ease of catalyst separation, recycle and reuse, and so forth. PEI with various Bronsted acid counterions such as H2SO4, H3PO4, TsOH, TfOH, and TFA provides the corresponding variables of PolyE-IL such as [PEI]+[HSO3]-, [PEI]+[H2PO4]-, [PEI]+[CF3CO2]-, [PEI]+[TfO]-, and [PEI]+[TsO]-, which are tested for fructose dehydration in the presence of IPA. Of the tested catalysts, only PolyE-IL with [HSO4]-, [CF3CO2]-, [TfO]-, and [TsO]- counterions showed the formation of 5-HMF. [PEI]+[HSO4]- showed the maximum yield of 5-HMF (61%) and selectivity (70%) with (87%) fructose conversion. Thus, further process optimization study was conducted to obtain the maximum yield, conversion, and selectivity. The intensified process provides a maximum yield of 5-HMF of 75% with 85% fructose conversion and 90% selectivity. The catalyst recyclability study showed the consistency in 5-HMF yield (75%), conversion (85%), and selectivity (90%) for five consecutive recycle runs. However, the study of reaction kinetics showed the first-order kinetics with an activation energy of 12.4 kJ/mole by using [PEI]+[HSO4]- catalyst. Thus, the use of an easily recyclable and robust catalyst provides an efficient route for production of 5-HMF in the presence of a green solvent.

Sc(OTf)3: An efficient homogeneous catalyst for microwave-assisted transfer hydrogenation of ethyl levulinate to γ-valerolactone under mild conditions

γ-Valerolactone (GVL) is considered as a versatile platform chemical obtained from biomass refinery. In this study, eco-friendly group III metal (Sc, Y, La) triflates were examined as homogeneous catalysts for microwave-assisted transfer hydrogenation of ethyl levulinate (EL) to GVL under mild conditions. Experimental results revealed that the selectivity of GVL has a positive relationship with the Lewis acidity of metal ion, which is related to effective charge density of the metal center (3.23, 2.81, 2.60 for Sc3+, Y3+, La3+, respectively). The stronger Lewis acidity of metal ion, the higher catalytic activity of MPV reduction. Among these catalysts, Sc(OTf)3 exhibited the best catalytic activity, achieving 98.4% EL conversion and 92.4% GVL yield at 140 °C in 3.0 h. Furthermore, Sc(OTf)3 showed high stability and recyclability for at least ten reaction cycles. In addition, a plausible reaction pathway and mechanism were proposed.