Triflate Catalyst Research Articles

Catalytic Cleavage of the C-O Bonds in Lignin and Lignin Model Compounds by Metal Triflate Catalysts.

The effective cleavage of C-O bonds in linkages of lignin was one of the significant strategies promoting lignin valorization. Herein, the strategy of C-O bonds cleavage of lignin using metal triflate as the catalyst was developed. The carboxylic acid or alcohol could be used as the nucleophile to stabilize the reactive intermediates formed during the depolymerization of lignin, and the corresponding ester/ether compounds could be obtained. This catalytic system was suitable for the C-O bond cleavage in α-O-4 and β-O-4 linkages with excellent efficiency. Additionally, reaction conditions were optimized. The reaction mixture was detected by 1 H NMR, and no other byproducts were found. As for treated lignin samples, the cleavage of C-O bonds in linkages was determined by 2D HSQC NMR, the increased content of the phenol hydroxyl group was proved by FT-IR, and the reduced molecular weight was investigated by GPC. Furthermore, multiple phenolic compounds were detected by GC-MS in the reaction mixtures.

Organocatalyst Promoted Efficient Synthesis of Carboxylic Acid Esters and its Application as Plasticizer for Polyvinyl Chloride

AbstractThe present work is related to the synthesis of a carboxylic acid ester using lab synthesized triphenylphosphonium triflate catalyst and its application as a plasticizer for polyvinyl chloride (PVC) processing. The high thermal stability of this organocatalyst allows the synthesis of terephthalic acid di‐esters with high boiling alcohols such as 1‐butanol, 2‐ethyl hexanol with higher yield in the range of 55–97 %. Different ester derivatives like dioctyl phthalate (DOP), dioctyl terephthalate (DOTP), n‐butyl benzoate, dibutyl terephthalate, dibutyl phthalate, and di‐dodecanol terephthalate have been synthesized using triphenylphosphonium triflate organocatalyst. These synthesized ester derivatives are characterized using 1H NMR, GC‐MS and HPLC. The purity of different synthesized esters was in the range of 80–99 %. The synthesized Dioctyl terephthalate (DOTP) was used as a plasticizer in PVC and compared the results with commercial DOP plasticizer performance for PVC. The PVC/DOTP composition exhibited comparable performance in terms of mechanical properties like tensile and flexural strength and modulus. No significant change found in hardness and impact strength of both the compositions. Ease of processing observed in case of PVC/DOTP composition due to lower torque as compared to PVC/DOP composition. This indicates DOTP can be a potential alternative to the traditional dioctyl phthalate (DOP) plasticizer for PVC processing.

Meso-Meso and β-Meso Imine-Bridged Thien-2-yl Porphyrin Dyads: Synthesis, Spectral and Electrochemical Investigations

Imine-bridged meso-meso and β-meso unsymmetrical thien-2-yl porphyrin dyads were synthesized by condensation of meso- and β-formyl derivatives of 5,10,15,20-tetrakis(3-methylthien-2-yl)porphyrinato nickel (II), Ni3MeThP with 5-(5-Aminothien-2-yl)-10,15,20-triphenylporphyrinato nickel(II), Ni5AThPP in the presence of lanthanum(III)triflate catalyst in toluene at 120 °C for 8 h. The structural, photophysical, and redox properties were investigated by 1H NMR, UV/Vis spectral, and electrochemical analysis. The near coplanarity of the linker thien-2-yl group with the central porphyrin π-system, which can influence the electron delocalization of these molecules, is explained using electronic spectroscopy and cyclic voltammetry. The stronger electronic interaction between the two porphyrin units and the increased nonplanarity of the macrocycle brought about by the β-meso imine bridging is indicated by the larger shift of redox potentials in the dyad-2 as compared to the dyad-1 system. The results of the present investigation reveal that the two distinct porphyrin units in dyads interact via their near planar thien-2-yl linker.

Efficient chemo-catalytic transformation of spent coffee grounds into lactic acid using erbium triflate

Developing efficient conversion technologies for waste valorization is crucial in the context of a sustainable bioeconomy. The massive generation of spent coffee grounds (SCG) has become an environmental and social concern. Although the majority of SCG is underutilized, it exhibits the potential to be converted into value-added products. Herein, we report the effective production of lactic acid (LA), a precursor of polylactic acid, from SCG through catalytic upcycling using an erbium triflate catalyst. The reaction conditions, including time, temperature, and catalyst loading, were optimized to maximize the LA yield. The proposed strategy converted SCG into LA with a high yield (70 mol%) within 1 h. The morphology and chemical structure of SCG were investigated. Additionally, a techno-economic analysis (TEA) was conducted, which demonstrated that an economically viable catalytic upcycling strategy can enhance the efficiency of the waste valorization process.

An efficient new method of ytterbium(III) triflate catalysis approach to the synthesis of substituted pyrroles: DFT, ADMET, and molecular docking investigations

In this study, the one-pot synthetic methodology for the preparation of substituted pyrroles with diethyl acetylene-dicarboxylate is reported for the various pyrrole derivatives via the Trifimow synthesis process from oximes. This method also offers the literature as a cyclization pathway using a ytterbium triflate catalyst. Another importance of this study is the use of pyrrole derivatives in pharmaceuticals, biological processes, and agrochemicals. From this point of view, the development of a new catalyst in synthetic organic chemistry and the difference in the method is also important. The syntheses of the target substituted pyrroles are accomplished in high yields. Also, all synthesized structures were confirmed by 1H NMR, 13C NMR, and IR spectra. The DFT computations were leveraged for structural and spectroscopic validation of the compounds. Then, FMO and NBO analyses were subsequently employed to elucidate the reactivity characteristics and intramolecular interactions within these compounds. Also, ADMET indices were ascertained to assess potential pharmacokinetic properties, drug-like qualities, and possible adverse effects of these compounds. Last, optimized molecules were analyzed by molecular docking methods against crystal structures of Bovine Serum Albumin and Leukemia Inhibitory Factor, and their binding affinities, interaction details, and inhibition constants were determined.

Lanthanum triflate as a capable catalyst for the synthesis of xanthenediones

The main purpose of this work was proposing a versatile and capable method for the synthesis of diverse xanthenediones from the three-component condensation reaction of two moles of dimedone and one mole of various aldehydes by the lanthanum triflate catalyst in solvent-free conditions at 60 °C. The products were characterized by comparison of their melting points, IR, and NMR spectra with authentic samples.

Unravelling stereoisomerism in acid catalysed lignin conversion: an integration of experimental trends and theoretical evaluations

Stereo preference of intermediates was observed during diol-stabilised lignin acidolysis, and the computational simulation revealed a role for the triflate catalyst.

Hybrid poly-ether/carbonate ester electrolyte engineering enables high oxidative stability for quasi-solid-state lithium metal batteries

Building safe and high-energy-density lithium metal batteries (LMBs) is currently being pursued to sustain our modern lifestyles. However, new electrolyte engineering is rigorously required that is capable of simultaneously providing good protection on lithium metal anode and sustaining high oxidative stability at the cathode, besides sufficient bulk conductivity and low interfacial resistance. Here, we report a novel hybrid poly-ether/carbonate ester quasi-solid-state electrolyte with high oxidative stability formed by a simple and efficient in situ polymerization of strategy, in which ring-opening polymerization of ether-based 1,3-dioxolane (DOL) and ester-based ethylene carbonate (EC)-ethylmethyl carbonate (EMC) is initiated by rare-earth triflate catalyst Sc(OTf)3 at room temperature. Such electrolyte engineering not only achieves a sufficiently high ionic conductivity of 5 × 10−4 S cm−1 but enables a high anodic voltage limit of 5 V while maintaining feasible battery manufacture technology. The hybrid poly-DOL/EC/EMC quasi-solid-state electrolyte is capable of producing a stable solid electrolyte interphase (SEI) featuring Li plating/stripping over 500 h at 0.5 mA cm−2 and decreased charge transfer resistance. The derived Li||LiFePO4 quasi-solid-state LMB, benefited from the enhanced oxidative stability of electrolyte, exhibits a notable capacity of 169 mAh g−1 at 1C with no capacity decay after 300 cycles.

A Hypervalent Cyclic Dibenzoiodolium Salt as a Halogen-Bond-Donor Catalyst for the [4+2] Cycloaddition of 2-Alkenylindoles.

A stable, hypervalent cyclic dibenzoiodolium salt acted as a strong halogen bonding (XB)-donor catalyst for [4+2] cycloaddition of 2-alkenylindoles, and not as an oxidizing agent. The cross-[4+2] cycloaddition of 2-vinylindoles with 2-alkenylindoles was catalyzed smoothly by the hypervalent cyclic dibenzoiodolium triflate catalyst to give the tetrahydrocarbazoles in up to 99 % yield with 17 : 1 diastereoselectivity. The hypervalent cyclic dibenzoiodolium salt was also applicable to the Povarov reaction of 2-vinylindole with N-p-methoxyphenyl (PMP) imine to give the indolyl-tetrahydroquinoline in 83 % yield.

Synthesis and properties of poly(1,3-dioxolane) in situ quasi-solid-state electrolytes via a rare-earth triflate catalyst.

We report a rare-earth triflate catalyst Sc(OTf)3 for the ring-opening polymerization of 1,3-dioxolane and the in situ production of a quasi-solid-state poly(1,3-dioxolane) electrolyte, which not only demonstrates a superior ionic conductivity of 1.07 mS cm-1 at room temperature, but achieves dendrite-free lithium deposition and a high Coulombic efficiency of 92.3% over 200 Li plating/striping cycles.

Bisbiphenyl Phosphines: Structure and Synthesis of Gold(I) Alkene π-Complexes with Variable Phosphine Donicity and Enhanced Stability

This paper describes the synthesis and characterization of RP(o-biphenyl)2 phosphine ligands (where R = PhO, Ph, and t-Bu), corresponding gold(I) chloride precatalysts, gold(I) triflate catalysts, and gold(I) π-complexes. All ligands and gold chlorides and three π-complexes were characterized in the solid state. The most significant differences between complexes in the solid state were varying P–Au bond lengths, a consistent reflection of the different electronic character of each phosphine. NMR spectroscopic data on enol ether π-complexes is consistent with increasing cationic character in the alkene fragment, from R = t-Bu to R = Ph and OPh. The intermolecular alkene exchange process for [LAu(methoxypropene)]SbF6 (L = PhO(o-biphenyl)2P) is faster than that of the analogous complex with t-Bu2(o-biphenyl)P, presumably due to the higher electrophilicity of the former complex. Examination of a series of vinyl silane π-complexes with triaryl phosphine ligands reveals increasing stability and ease of preparation (Ph3P < Ph2P(o-biphenyl) < PhP(o-biphenyl)2). These results reveal that incorporation of a second biphenyl substituent into ligand architectures allows preparation of a series of gold π-complexes with increased stability over a range of phosphine donicity.

Tetrabutylammonium‐Bromide‐Promoted Synthesis of Spirooxindoles through Alkyne‐Aldehyde C−C Coupling and 1,3‐Dipolar Cycloaddition Using Ytterbium Triflate Catalyst

AbstractTetrabutylammonium‐bromide promoted, ytterbium triflate catalyzed one‐pot domino synthesis of spirooxindoles is described. The hydration‐condensation of alkyne, 1 aldehyde, 2 C−C coupling followed by 1,3‐dipolar cycloaddition of in‐situ generated azomethine ylide from Isatin, 3 and L‐proline, 4 a or sarcosine, 4 b furnished novel spirooxindoles, 5 under solvent‐free green‐chemical conditions, in high regio and stereo selectivities and yields. The regio and stereochemistry of the synthesized derivatives were characterized by 2D NMR Spectroscopic studies.

Functionalization of a Single C-F Bond of Trifluoromethylarenes Assisted by an ortho-Silyl Group Using a Trityl-Based All-in-One Reagent with Ytterbium Triflate Catalyst.

Catalytic thiolation and azidation of a single C-F bond of trifluoromethylarenes were achieved assisted by an ortho-silyl group with all-in-one reagents to generate a trityl cation and nucleophiles. The reactions catalyzed by ytterbium triflate efficiently afforded a wide variety of difluoromethylenes avoiding the further C-F bond cleavage, by virtue of the mild conditions without the generation of a Brønsted acid.

Palladium-Based Hydroamination Catalysts Employing Sterically Demanding 3-Iminophosphines: Branched Kinetic Products by Prevention of Allylamine Isomerization

A new allylpalladium triflate catalyst with a dimesitylphosphine moiety was synthesized, isolated, and characterized. The greatly increased steric bulk on the phosphine of this palladium catalyst inhibited product isomerization, which is often observed after hydroamination of terminal allenes with secondary amines. The considerably reduced rate of isomerization facilitated the isolation of many previously unknown branched allylamines, products that were inaccessible when using other, more active 3-iminophosphine palladium catalysts.

One-Pot Synthesis of Substituted Phthalazine-5,10-dione Derivatives in the Presence of Triflate Catalyst

In this study, substituted 1H-pyrazolo[1,2-b]phthalazine-5,10-diones which are considered that may possess biological activity have been obtained via one-pot multi-component cyclocondensation reaction of phthalhydrazide, aromatic aldehydes and malononitrile catalyzed in the presence of Cu(OTf)2 in very good yields and short times. The structures of all these synthesized compounds (4a-f) have been determined and characterized by infrared, nuclear magnetic resonance, mass spectral data, and elemental analysis.

Fused Bis-lactams to Spirolactams: A New Member of the Family of Ring- Contraction Reaction

A new ring contraction of fused bis-lactams into spirolactams is presented here. In the presence of a triflate catalyst in various solvents under microwave irradiation, this rearrangement allows a clean conversion of some fused bicycles into spirocycles with good yields. The interest of this work thus lies in the use of activated 2,5-diketopiperazines as starting materials and demonstrates the wide range of applications of ring contraction reactions

Selective conversion of glucose into lactic acid with immobilized ytterbium triflate

Ytterbium triflate was immobilized on SBA-15 via chemical grafting and co-condensation and the catalytic performance of the immobilized ytterbium triflate for the selective conversion of glucose into lactic acid was investigated in this paper. The characterization results showed that ytterbium triflate was immobilized on SBA-15 successfully. It was found that the immobilized ytterbium triflate catalyst can catalyze the transformation of glucose into lactic acid effectively. The 58.01% yield of lactic acid was obtained from glucose at 200 °C. The HPLC analysis results of the products showed that the glyceraldehyde might act as an intermediate for the formation of lactic acid during the reaction. The immobilized ytterbium triflate catalyst was recycled for more than five times without noticeable loss in activity.

Surface modified alginate multicore microcapsules and their application in self-healing epoxy coatings for metallic protection

Conventionally, self-healing microcapsules are synthesized from synthetic polymers associated with complicated fabrication process. It appears in the range of (10–400 μm) to suit different applications. Here, we report green self-healing microcapsules synthesized from alginate biopolymer. The synthesis process is straightforward, require no pH and temperature change. Using simple methods (electrospraying and air atomization), alginate/epoxy microcapsules of two size range (∼350 μm and ∼150 μm) are fabricated. However, the smaller air atomized microcapsules collapsed after drying. Chitosan coating successfully provides structural support to small air atomized microcapsules and improves the elastic modulus of both microcapsules. Peak force quantitative nanomechanical mapping (PFQNM) under atomic force microscopy (AFM) is used to acquire the capsules elastic modulus. Chitosan coating slightly improved the elastic modulus of electrosprayed microcapsules from 3.43 ± 0.80 GPa to 4.45 ± 0.80 GPa. Although HNTs are unable to enhance the structural integrity of small microcapsules, it improves the elastic modulus of big microcapsules up to 6.04 ± 0.20 GPa. To evaluate the self-healing ability, these microcapsules and Scandium (III) triflate catalyst are incorporated into epoxy coating and applied on a metallic substrate. The capsule-catalyst self-healing coatings showed good self-healing performance in closing the gaps on the scratch.

Synthesis of New α-Amino Phosphonates Containing 3-Amino-4(3H) Quinazolinone Moiety as Anticancer and Antimicrobial Agents: DFT, NBO, and Vibrational Studies

Aim and Objective: Synthesis of new .-aminophosphonates containing quinazoline moiety through Kabachnik-Fields reaction in the presence of copper triflate catalyst [32], followed by studying their antimicrobial activities and in vitro anticancer activities against liver carcinoma cell line (HepG2) with the hope that new anticancer agents could be developed. Also, the quantum chemical calculations are performed using density functional theory (DFT) to study the effect of the changes of molecular and electronic structures on the biological activity of the investigated compounds. Materials and Method: The structures of the synthesized compounds are confirmed by FT-IR, 1H NMR, 13C NMR, 31P NMR and MS spectral data. The synthesized compounds show significant antimicrobial and also remarkable cytotoxicity anticancer activities against liver carcinoma cell line (HepG2). Density functional theory (DFT) was performed to study the effect of the molecular and electronic structure changes on the biological activity. Results: It was found that the electronic structure of the substituents affects on the reaction yield. The electron withdrawing substituent, NO2 group 3b, on the aromatic aldehydes gave a good yield more than the electron donating substituent, OH group 3c. The electron deficient on the carbon atom of the aldehydic group may increase the interaction of the Lewis acid (Cu(OTf)2) and the Lewis base (imine nitrogen), and accordingly, facilitate the formation of imine easily, which is attacked by the nucleophilic phosphite species to give the α- aminophosphonates. Conclusion: The newly synthesized compounds exhibit a remarkable inhibition of the growth of Grampositive, Gram-negative bacteria and fungi at low concentrations. The cytotoxicity of the synthesized compounds showed a significant cytotoxicity against the liver cancer cell line (HepG 2). Also, it was shown from the quantum chemical calculations that the electron-withdrawing substituent increases the biological activity of the α-aminophosphonates more than the electron donating group which was in a good agreement with the experimental results. Also, a good agreement between the experimental FT-IR and the calculated one was found.

Hafnium inspired activation of highly hindered anhydrides in the acylation of alcohols and polyols

A novel and highly efficient method for activating highly hindered acid anhydrides towards the acylation of alcohols and carbohydrate-derived polyols has been developed. This new method relies on the capacity of the hafnium triflate catalyst Hf(OTf)2 to activate highly hindered acid anhydrides, and to direct the acylation reaction. This new acylation protocol is mild and proceed at room temperature with low catalyst loading. The method is versatile and has been extended to different alcohol substrates with different steric encumbrance as well as carbohydrate-derived polyols to afford the corresponding ester products in good to excellent yields.