Showing papers on "Carboxylic acid published in 2021"
71 citations
TL;DR: In this article, a SO3H-anchored covalent organic framework (TpPa-SO3H) was deliberately designed by linking phenolic trialdehyde with triamine through Schiff reaction.
49 citations
TL;DR: In this paper, four luminescent metal-organic frameworks (F1, F2, F3, F4) containing cadmium ions, carboxylic acid ligands, and anthracene nitrogen-containing organic ligand (9,10-bis(N-benzimidazolyl)-anthracene, L) were synthesized by a one-pot synthesis under solvothermal conditions.
41 citations
TL;DR: C(1)‐Ammonium enolates are powerful, catalytically generated synthetic intermediates applied in the enantioselective α‐functionalisation of carboxylic acid derivatives using isothiourea Lewis base organocatalysts using two distinct catalyst turnover approaches.
Abstract: C(1)-Ammonium enolates are powerful, catalytically generated synthetic intermediates applied in the enantioselective α-functionalisation of carboxylic acid derivatives This minireview describes the recent developments in the generation and application of C(1)-ammonium enolates from various precursors (carboxylic acids, anhydrides, acyl imidazoles, aryl esters, α-diazoketones, alkyl halides) using isothiourea Lewis base organocatalysts Their synthetic utility in intra- and intermolecular enantioselective C-C and C-X bond forming processes on reaction with various electrophiles will be showcased utilising two distinct catalyst turnover approaches
40 citations
TL;DR: In this paper, diamine and carboxylic acid groups were used for the preparation of cyclic carbonates by cycloaddition reactions of CO2 and epoxides.
39 citations
30 citations
TL;DR: In this article, the electrochemical fixation of carbon dioxide to organic compounds with carbon-carbon bond forming reactions yielding novel and useful carboxylic acids are introduced along with their applications and some new results.
Abstract: In the past three decades, we have focused on the fixation of carbon dioxide by electrochemical method with a carbon-carbon bond forming reaction to yield carboxylic acid, so-called electrochemical carboxylation. Vinyl bromides and triflates, difluoroethylbenzenes, polyfluoroarenes, benzal diacetates, phenyl-substituted alkenes and enamides, and α-aminosulfones were found to be effective as substrates for electrochemical carboxylation. Phenylacetic acids and phenylpropanoic acids including non-steroidal anti-inflammatory agents and their fluorinated analogues, polyfluorobenzoic acids, mandel acetates, and α- and β-amino acids were successfully synthesized. Electrochemical double carboxylation of dibenzyl carbonates, reuse of carbon dioxide in benzyl carbonates for fixation of carbon dioxide (recycle-electrochemical carboxylation), sequential aryl/vinyl radical cyclization-electrochemical carboxylation, sacrificial anode-free electrochemical carboxylation, and the use of supercritical carbon dioxide both as a reaction media and a reagent were also developed. In this personal account, our efforts in and results of electrochemical fixation of carbon dioxide to organic compounds with carbon-carbon bond forming reactions yielding novel and useful carboxylic acids are introduced along with their applications and some new results.
29 citations
TL;DR: Asymmetric ruthenium-catalyzed C-H alkylations were enabled by a chiral C2-symmetric carboxylic acid.
27 citations
TL;DR: In this article, a novel copper-catalyzed carbonylative trifluoromethylation of unactivated alkenes has been developed, and a broad range of β-trifluorsomethymylated carboxylic acid derivatives were prepared in moderate to excellent yields from simple alkenES with excellent regioselectivity.
Abstract: A novel copper-catalyzed carbonylative trifluoromethylation of unactivated alkenes has been developed. A broad range of β -trifluoromethylated carboxylic acid derivatives were prepared in moderate to excellent yields from simple alkenes with excellent regioselectivity. It is noteworthy that ethylene gas, as the simplest olefin, can also be applied directly to obtain β -trifluoromethylated amides and ester. This transformation presents the first example on carbonylative trifluoromethylation of alkenes.
26 citations
TL;DR: This mini-review summarizes the recent progress in the chemo-catalytic and/or bio-Catalytic conversion of furfural into high-value-added chemicals, including furfurylamine, C6 carboxylic acid, and cyclopentanone, particularly the advances in the catalytic valorization of fur fural into useful chemicals in the last few years.
Abstract: Furfural is a promising renewable platform molecule derived from hemi-cellulose, which can be further converted to fossil fuel alternatives and valuable chemicals due to its highly functionalized molecular structure. This mini-review summarizes the recent progress in the chemo-catalytic and/or bio-catalytic conversion of furfural into high-value-added chemicals, including furfurylamine, C6 carboxylic acid, i.e., furandicarboxylic acid, furfural alcohol, aromatics, levulinic acid, maleic acid, succinic acid, furoic acid, and cyclopentanone, particularly the advances in the catalytic valorization of furfural into useful chemicals in the last few years. The possible reaction mechanisms for the conversion of furfural into bio-chemicals are summarized and discussed. The future prospective and challenges in the utilization of furfural through chemo- and bio-catalysis are also put forward for the further design and optimization of catalytic processes for the conversion of furfural.
25 citations
TL;DR: In this article, a reagent system was proposed to obtain acyl fluorides directly from three different functional group precursors: carboxylic acids, aldehydes, or alcohols.
TL;DR: Three main components of sugarcane bagasse namely cellulose, hemicellulose, and lignin were isolated and esterified by citric acid under the same conditions and proved to participate in adsorption and induce the esterification withcitric acid.
Abstract: In this study, different pretreatment strategies of sugarcane bagasse prior to citric acid modification were investigated in terms of Pb2+ adsorption capacity. Pretreatment strategies included the use of NaOH, HCl, and C2H5OH in various concentrations. In order to fundamentally understand how these pretreatment methods affect the modification of sugarcane bagasse by citric acid as well as the Pb2+ adsorption capacity of sugarcane bagasse, three main components of sugarcane bagasse namely cellulose, hemicellulose, and lignin were isolated and esterified by citric acid under the same conditions. ATR-FTIR, XPS, SEM, and an analysis of the number of carboxylic acid groups were used to investigate the physicochemical and chemical properties of the materials. These three components were proved to participate in adsorption and induce the esterification with citric acid. Hence, pretreatment with ethanol and 0.01 M NaOH which could retain cellulose, hemicellulose, and lignin in sugarcane bagasse achieved a high Pb2+ adsorption capacity, i.e., 122.4 and 97 mg/g after the esterification with citric acid. In contrast, pretreatment with 0.5 M NaOH and 0.1 M HCl removed lignin and hemicellulose, leading to the lowest value of approximately 45 mg/g for citric acid esterified-pretreated sugarcane bagasse. XPS analysis and number of carboxylic group measurement confirmed the esterification between bagasse and citric acid. To understand the adsorption mechanism of adsorbent, two kinetic models including pseudo-first-order model and pseudo-second-order model were applied. The experimental data were well described by the pseudo-second-order model. The adsorption isotherm data were fitted Langmuir and Freundlich.
TL;DR: In this article, the authors show that controlling the degree of esterification can significantly improve the stability of lignin oleate nanoparticles (OLNPs) in acidic and basic aqueous dispersions.
Abstract: Lignin nanoparticles (LNPs) are promising renewable nanomaterials with applications ranging from biomedicine to water purification. However, the instability of LNPs under acidic and basic conditions severely limits their functionalization for improved performance. Here, we show that controlling the degree of esterification can significantly improve the stability of lignin oleate nanoparticles (OLNPs) in acidic and basic aqueous dispersions. The high stability of OLNPs is attributed to the alkyl chains accumulated in the shell of the particle, which delays protonation/deprotonation of carboxylic acid and phenolic hydroxyl groups. Owing to the enhanced stability, acid- and base-catalyzed functionalization of OLNPs at pH 2.0 and pH 12.0 via oxirane ring-opening reactions were successfully performed. We also demonstrated these new functionalized particles as efficient pH-switchable dye adsorbents and anticorrosive particulate coatings.
TL;DR: A weakly coordinated carboxylate-directed palladium-catalyzed atroposelective C-H alkynylation method for the development of novel axially chiral styrene-type carboxylic acids is disclosed in this paper.
TL;DR: In this paper, an enantioselective CuH-catalyzed hydrocarboxylation of allenes with a commercially available fluoroformate was reported, yielding α-chiral carboxylic acid derivatives with exclusive branched regioselectivity.
Abstract: We report a method to prepare α-chiral carboxylic acid derivatives, including those bearing all-carbon quaternary centers, through an enantioselective CuH-catalyzed hydrocarboxylation of allenes with a commercially available fluoroformate. A broad range of heterocycles and functional groups on the allenes were tolerated in this protocol, giving enantioenriched α-quaternary and tertiary carboxylic acid derivatives in good yields with exclusive branched regioselectivity. The synthetic utility of this approach was further demonstrated by derivatization of the products to afford biologically important compounds, including the antiplatelet drug indobufen.
28 May 2021
TL;DR: A comprehensive review of the acceptorless dehydrogenation of primary alcohols to carboxylates can be found in this article, where a number of transition-metal compounds have been used as catalysts for the process.
Abstract: Oxidation of primary alcohols to carboxylic acids is a fundamental transformation in organic chemistry, yet despite its simplicity, extensive use, and relationship to pH, it remains a subject of active research for synthetic organic chemists. Since 2013, a great number of new methods have emerged that utilize transition-metal compounds as catalysts for acceptorless dehydrogenation of alcohols to carboxylates. The interest in this reaction is explained by its atom economy, which is in accord with the principles of sustainability and green chemistry. Therefore, the methods for the direct synthesis of carboxylic acids from alcohols is ripe for a modern survey, which we provide in this review. 1 Introduction 2 Thermodynamics of Primary Alcohol Oxidation 3 Oxometalate Oxidation 4 Transfer Dehydrogenation 5 Acceptorless Dehydrogenation 6 Electrochemical Methods 7 Outlook
TL;DR: An iridium-catalyzed reductive three-component coupling reaction for the synthesis of medicinally relevant α-amino 1,3,4-oxadiazoles from abundant tertiary amides or lactams, carboxylic acids, and (N-isocyanimino) triphenylphosphorane, is described in this paper.
Abstract: An iridium-catalyzed reductive three-component coupling reaction for the synthesis of medicinally relevant α-amino 1,3,4-oxadiazoles from abundant tertiary amides or lactams, carboxylic acids, and (N-isocyanimino) triphenylphosphorane, is described. Proceeding under mild conditions using (<1 mol %) Vaska's complex (IrCl(CO)(PPh3 )2 ) and tetramethyldisiloxane to access the key reactive iminium ion intermediates, a broad range of α-amino 1,3,4-oxadiazole architectures were accessed from carboxylic acid feedstock coupling partners. Extension to α-amino heterodiazole synthesis was readily achieved by exchanging the carboxylic acid coupling partner for C-, S-, or N-centered Bronsted acids, and provided rapid and modular access to these desirable, yet difficult-to-access, heterocycles. The high chemoselectivity of the catalytic reductive activation step allowed late-stage functionalization of 10 drug molecules, including the synthesis of heterodiazole-fused drug-drug conjugates.
TL;DR: In this article, a density functional theory (DFT) combined with molecular dynamics simulation was employed to explore the involved micro-mechanism of low-rank coal flotation.
TL;DR: Crystal analysis, good detonation properties, and low sensitivities of these trifluoromethyl and dinitro- or trinitro -based triazoles suggest their role as potential candidates for insensitive high-energy-density materials.
TL;DR: In this article, the reduction of 2-furancarboxylic acid (FCA) and 2-5-furandicarboxyl acid (FDCA) with H 2 without reduction of the carboxyl groups is reviewed.
Abstract: Catalytic reduction systems of 2-furancarboxylic acid (FCA) and 2,5-furandicarboxylic acid (FDCA) with H2 without reduction of the carboxyl groups are reviewed. FCA and FDCA are produced from furfural and 5-hydroxymethylfurfural which are important platform chemicals in biomass conversions. Furan ring hydrogenation to tetrahydrofuran-2-carboxylic acid (THFCA) and tetrahydrofuran-2,5-dicarboxylic acid (THFDCA) easily proceeds over Pd catalysts. Hydrogenolysis of one C–O bond in the furan ring produces 5-hydroxyvaleric acid (5-HVA) and 2-hydroxyadipic acid. 2-Hydroxyvaleric acid is not produced in the reported systems. 5-HVA can be produced as the lactone form (δ-valerolactone; DVL) or as the esters depending on the solvent. These reactions proceed over Pt catalysts with good yields (~ 70%) at optimized conditions. Hydrogenolysis of two C–O bonds in the furan ring produces valeric acid and adipic acid, the latter of which is a very important chemical in industry and its production from biomass is of high importance. Adipic acid from FDCA can be produced directly over Pt-MoOx catalyst, indirectly via hydrogenation and hydrodeoxygenation as one-pot reaction using the combination of Pt and acid catalysts such as Pt/niobium oxide, or indirectly via two-step reaction composed of hydrogenation catalyzed by Pd and hydrodeoxygenation catalyzed by iodide ion in acidic conditions. Only the two-step method can give good yield of adipic acid at present.
TL;DR: In this article, the authors describe a process to extract rare earth elements from coal ash using low molecular weight carboxylic acids, i.e., thartaric acid, lactic acid and succinic acid.
TL;DR: In this paper, it has been shown that aliphatic C-H oxidations by bio-inspired catalyst systems Mn aminopyridine complex/H2O2/carboxylic acid in acetonitrile afford predominantly a mixture of the cor...
Abstract: In this work, it has been shown that aliphatic C–H oxidations by bioinspired catalyst systems Mn aminopyridine complex/H2O2/carboxylic acid in acetonitrile afford predominantly a mixture of the cor...
TL;DR: Mechanistic investigations demonstrate that the reaction of copper salt and oxidant (NH4)2S2O8 allows for achievement of tandem processes, including deprotonation, free-radical-mediated denitrogenation, and C-S bond formation.
Abstract: An alternative thioesterification reaction via copper-catalyzed oxidative coupling of readily available aroylhydrazides with disulfides is developed, in which oxidative expulsion of N2 overcomes the activation barrier between the carboxylic acid derivatives and the products. The reaction produces various thioesters in good to excellent yields with good functional group tolerance. In the reaction, stable and easily available aroylhydrazides are used as acyl sources and the relatively odorless disulfides are used as S sources. Mechanistic investigations demonstrate that the reaction of copper salt and oxidant (NH4)2S2O8 allows for achievement of tandem processes, including deprotonation, free-radical-mediated denitrogenation, and C-S bond formation.
TL;DR: In this paper, the application of pentafluoropyridine (PFP) in the deoxyfluorination of carboxylic acids to acyl fluorides was described.
TL;DR: Ru(II)-catalyzed enantioselective C–H functionalization reactions of sulfoximines with sulfoxonium ylides are described, which furnished the S-chiral products in 76:24–92:8 er.
Abstract: Ru(II)-catalyzed enantioselective C–H functionalization reactions of sulfoximines with sulfoxonium ylides are described. The combination of [RuCl2(p-cymene)]2 and a pseudo-C
2-symmetric binaphthyl monocarboxylic acid furnished the S-chiral products in 76:24–92:8 er.
TL;DR: In this article, a facile, efficient, and transition-metal-free chemodivergent C-3 functionalization of 2H-indazoles was developed under aerobic conditions using carboxylic acid and DMSO as the combined source of the CAREs and formylating agent.
Abstract: A facile, efficient, and transition-metal-free chemodivergent C-3 functionalization of 2H-indazoles was developed under aerobic conditions using carboxylic acid and DMSO as the combined source of the carboxylic acid ester group and DMSO as the formylating agent. A series of formylated indazoles and carboxylic acid esters of indazole derivatives were produced in moderate to excellent yields. The mechanistic studies suggest that the reactions probably proceed through a radical pathway.
TL;DR: In this paper, the carboxylic acid-selective, catalytic, asymmetric aldol reaction of multifunctional substrates is proposed. But the reaction mechanism is still difficult to achieve.
Abstract: The catalytic asymmetric aldol reaction is among the most useful reactions in organic synthesis. Despite the existence of many prominent reports, however, the late-stage, chemoselective, catalytic, asymmetric aldol reaction of multifunctional substrates is still difficult to achieve. Herein, we identified that in situ pre-conversion of carboxylic acids to siloxy esters facilitated the boron-catalyzed direct aldol reaction, leading to the development of carboxylic acid-selective, catalytic, asymmetric aldol reaction applicable to multifunctional substrates. Combining experimental and computational studies rationalized the reaction mechanism and led to the proposal of Si/B enediolates as the active species. The silyl ester formation facilitated both enolization and catalyst turnover by acidifying the α-proton of substrates and attenuating poisonous Lewis bases to the boron catalyst.
TL;DR: In this paper, the authors introduced heteromeric carboxylic acid dimers to construct a non-interpenetrated molecular crystal and crosslinked this crystal precursor with dithiols to obtain a large pore single-crystalline hydrogen-bonded crosslinked organic framework HC OF-101.
Abstract: The development of large pore single-crystalline covalently linked organic frameworks is critical in revealing the detailed structure-property relationship with substrates. One emergent approach is to photo-crosslink hydrogen-bonded molecular crystals. Introducing complementary hydrogen-bonded carboxylic acid building blocks is promising to construct large pore networks, but these molecules often form interpenetrated networks or non-porous solids. Herein, we introduced heteromeric carboxylic acid dimers to construct a non-interpenetrated molecular crystal. Crosslinking this crystal precursor with dithiols afforded a large pore single-crystalline hydrogen-bonded crosslinked organic framework HC OF-101. X-ray diffraction analysis revealed HC OF-101 as an interlayer connected hexagonal network, which possesses flexible linkages and large porous channels to host a hydrazone photoswitch. Multicycle Z/E-isomerization of the hydrazone took place reversibly within HC OF-101, showcasing the potential use of HC OF-101 for optical information storage.
TL;DR: In this article, novel hydrophobic deep eutectic solvents (DESs) based on amides as hydrogen bond acceptors (HBAs) and terpenes as hydrogen-bond donors (HBDs) were proposed for carboxylic acid extraction.