Enabling heterogeneous catalysis to achieve carbon neutrality: Directional catalytic conversion of CO_(2) into carboxylic acids

The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving carbon neutrality is the utilization of CO_(2) under economic and sustainable conditions.Recently,the strong need for carbon neutrality has led to a proliferation of studies on the direct conversion of CO_(2) into carboxylic acids,which can effectively alleviate CO_(2) emissions and create high-value chemicals.The purpose of this review is to present the application prospects of carboxylic acids and the basic principles of CO_(2) conversion into carboxylic acids through photo-,electric-,and thermal catalysis.Special attention is focused on the regulation strategy of the activity of abundant catalysts at the molecular level,inspiring the preparation of high-performance catalysts.In addition,theoretical calculations,advanced technologies,and numerous typical examples are introduced to elaborate on the corresponding process and influencing factors of catalytic activity.Finally,challenges and prospects are provided for the future development of this field.It is hoped that this review will contribute to a deeper understanding of the conversion of CO_(2) into carboxylic acids and inspire more innovative breakthroughs.

Comparison of Carboxylic Acids in Some Crude Oils and Their Diesel Distillates and VGOs:Characterized by Negative-Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (Negative-Ion ESI FT-ICR MS)

Three high-acidity crudes, Dar, SZ36-1, and QHD326, were separated through distillation into several fractions, including diesel distillates, and VGOs. Samples were characterized by negative-ion ESI FT-ICR MS. The O2 class species （petroleum carboxylic acids）, which have a close relationship with corrosion of equipment caused by high-acidity crudes, were put in the focus of attention and were discussed in this paper. Monocyclic, bicyclic, and tricyclic naphthenic acids are the main types of petroleum carboxylic acids in naphthenic-base crudes （SZ36-1 and QHD326）. But the main types of petroleum carboxylic acids in paraffinic-base crude （Dar） are aliphatic acids and monocyclic naphthenic acids. The O2 class species in SZ36-1 and QHD326 are distributed in a wider range and have bigger DBE value （double-bond equivalence value） and carbon number than Dar. Bicyclic naphthenic acids have the highest proportion among petroleum carboxylie acids in diesel distillates, but monocyclic and tricyclic naphthenic acids also occupy a high proportion. Particularly, aliphatic acids in the diesel distillate of Dar still have high proportion among petroleum carboxylic acids. The distribution of petroleum carboxylic acids in VGO is basically identical. The bicyclic naphthenic acids assume the first place （about 25 m%）, while the monocyclic and tricyclic naphthenic acids take the next place. The comparison of petroleum carboxylic acids in diesel distillates and VGOs has revealed that the molecules of carboxylic acids in VGOs are not only bigger but also more complicated.

Robust cobalt oxide catalysts for controllable hydrogenation of carboxylic acids to alcohols

The selective catalytic hydrogenation of carboxylic acids is an important process for alcohol production,while efficient heterogeneous catalyst systems are still being explored.Here,we report the selective hydrogenation of carboxylic acids using earth‐abundant cobalt oxides through a reaction‐controlled catalysis process.The further reaction of the alcohols is completely hindered by the presence of carboxylic acids in the reaction system.The partial reduction of cobalt oxides by hydrogen at designated temperatures can dramatically enhance the catalytic activity of pristine samples.A wide range of carboxylic acids with a variety of functional groups can be converted to the corresponding alcohols at a yield level applicable to large‐scale production.Cobalt monoxide was established as the preferred active phase for the selective hydrogenation of carboxylic acids.

Theoretic Simulation of Pr^(3+) and Nd^(3+) Complexes with αHydroxyl Carboxylic Acids

The potential energy difference of trivalent Pr/Nd complex ions with various α hydroxyl carboxylic acids were computed by molecular mechanics plus(MM +) model. Its relationships with the steric hindrance of the coordinating lignads and with the separation factor of Pr/Nd were discussed. It is found that the MM + model can be used for selecting and designing ligand as effective eluant, with which Pr 3+ and Nd 3+ can be separated by ion exchange chromatography.

Distribution of Carboxylic Acids in Sudanese Dar Crude Oil: Characterized by Negative-Ion Electrospray Ionization Fou- rier Transform Ion Cyclotron Resonance Mass Spectrometry

The Dar crude oil produced in Sudan was distilled into several fractions. The heteroatom class species in crude and its fractions were characterized by the negative-ion ESI FT-ICR MS. The major emphasis was put upon the study on the O2 class species (petroleum carboxylic acids). The test results revealed that aliphatic acids and monocyclic naphthenic acids accounted for a large proportion in petroleum carboxylic acids of the Dar crude. The relative abundance of aliphatic acids and monocyclic naphthenic acids decreased with an increasing boiling point of fractions. Meanwhile, the relative abundance of bicyclic and tricyclic naphthenic acids increased at first and then decreased, whereas the relative abundance of petroleum carboxylic acids with higher double-bond equivalence (DBE) values increased. The high abundance of aliphatic acids in the Dar crude and its fractions covered the carbon numbers in a range of 16 to 18 which had important geochemical signifi- cance. The O2 class species were distributed in a broad range of DBE values and carbon numbers with increasing boiling points of fractions.

Using the Chiral Organophosphorus Derivatizing Agents for Determination of the Enantiomeric Composition of Chiral Carboxylic Acids by ^(31)PNMR Spectroscopy

The use of chiral organophosphoras derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the 31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The method is accurate, reliable and convenient.

Solvent-Free Synthesis of Carboxylic Acids and Amide Analogs of CAPE(Caffeic Acid Phenethyl Ester)under Infrared Irradiation Conditions

A convenient and easy method is described for the formation of carboxamides from carboxylic acids and primary amines in solventless conditions using infrared (IR) light. Thus, under IR light, cinnamic acid derivatives and amines can produce yields ranging from 50% to 85% of the resulting amide.

Sulfonated carbon catalyzed oxidation of aldehydes to carboxylic acids by hydrogen peroxide

Sulfonated carbon as a strong and stable solid acid catalyst exhibited excellent catalytic performance in various acid-catalyzed reactions. Here, sulfonated carbon, as catalyst for oxidation reaction, was prepared via the carbonization of starch followed by sulfonation with concentrated sulfuric acid. N2 physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray fluorescence and acid-base titration were used to characterize the obtained materials. The catalytic activity of sulfonated carbon was studied in the oxidation of aldehydes to carboxylic acids using 30 wt% H2O2 as oxidant. This oxidation protocol works well for various aldehydes including aromatic and aliphatic aldehydes. The sulfonated carbon can be recycled for three times without obvious loss of activity.

Efficient Fixation of Carbon Dioxide by Electrolysis——Facile Synthesis of Useful Carboxylic Acids

Electrochemical fixation of atmospheric pressure of carbon dioxide to organic compounds is a useful and attractive method for synthesizing of various carboxylic acids. Electrochemical fixation of carbon dioxide, electrochemical carboxylation, organic halides, organic triflates, alkenes, aromatic compounds, and carbonyl compounds can readily occur in the presence of an atmospheric pressure of carbon dioxide to form the corresponding carboxylic acids with high yields, when a sacrificial anode such as magnesium or aluminum is used in the electrolysis. The electrochemical carboxylation of vinyl bromides was successfully applied for the synthesis of the precursor of nonsteroidal anti-inflammatory agents such as ibuprofen and naproxen. On the other hand, supercritical carbon dioxide （scCO2） has significant potential as an environmentally benign solvent in organic synthesis and it could be used both as a solvent and as a reagent in these electrochemical carboxylations by using a small amount of cosolvent.

Reductive Conversion of Biomass-Derived Furancarboxylic Acids with Retention of Carboxylic Acid Moiety

Catalytic reduction systems of 2-furancarboxylic acid(FCA)and 2,5-furandicarboxylic acid(FDCA)with H 2 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-MoO_(x) 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.

Syntheses,Crystal Structures,and Magnetic Properties of Two Manganese(Ⅱ) Coordination Polymers Based on Bifunctional Pyridine-benzene Carboxylic Acids

Two manganese（II） coordination polymers, namely, {[Mn（PIP）（BIBP）]·（BIBP）0.5}n（1） and {[Mn（PTA）（BIMBP）（H2O）]·H2O（0.69）}n（2）（H2PIP = 5-（4-pyridyl）-isophthalic acid, H2 PTA =6-（4-pyridyl）-terephthalic acid, BIBP = 4,4？-bis（imidazol-1-yl）biphenyl, and BIMBP =4,4？-bis（imidazol-1-ylmethyl）biphenyl）, have been synthesized by using the bifunctional pyrinde-benzene carboxylic acids and bis（imidazole） linkers as mixed ligands to react with Mn SO4,and further characterized by elemental analysis, IR, and PXRD. Compound 1 is in the triclicnic system, space group P1 with a = 10.1089（8）, b = 13.1927（12）, c = 14.0638（12）A, α = 69.437（2）, β= 73.2890（10）, γ = 78.5320（10）o, V = 1671.9（2） A^3, Z = 2, Dc = 1.449 g/cm^3, F（000） = 705,μ（MoK α） = 0.453 mm^-1, S = 1.053, R = 0.0491 and wR = 0.1367 for 5837 unique reflections（Rint =0.0208） with I 〉 2σ（I）. Compound 2 belongs to the monoclicnic system, space group C2/c with a =15.199（3）, b = 19.731（3）, c = 21.537（5） ？, β = 105.228（3）o, V = 6232（2） A^3, Z = 8, Dc = 1.363g/cm^3, F（000） = 2648, μ（MoK α） = 0.475 mm^-1, S = 1.048, R = 0.0489 and wR = 0.1151 for 7414 unique reflections（Rint = 0.0425） with I 〉 2σ（I）. Structural analyses reveal that complex 1 is a4-connected（44.62）-sql bilayer structure with binuclear [Mn2（COO）2] SBU, while complex 2 is a normally（3,5）-connected（42.67.8）（42.6）-3,5L2 monolayer. And the sheets interacted with the adjacent sheets through weak interactions, finally giving a stable three-dimensional（3D）supramolecule. Besides, the variable-temperature magnetic susceptibility measurement of complex1 was investigated.

SURFACE MODIFICATION OF CaCO_3 WITH DENDRITIC CARBOXYLIC ACIDS

Nanometer calcium carbonate was modified with Frechet type polyether dendrons bearing a COOH group at thefocal point by a wet-coating technique in dichloromethane at room temperature. The interaction between CaCO;and thedendritic modifier was proven by IR and mass spectroscopy of the modified CaCO;after thorough extraction withdichloromethane. The amount of tightly bonded organic modifier was estimated by TGA. It was shown that the amount ofbonded molecules decreased with increasing generation number due to the larger number of branches. Compared tounmodified CaCO;, the modified CaCO;possess different dispersibility in water and in organic solvents.

Biomimetic Decarboxylation of Carboxylic Acids with PhI(OAc)_2 Catalyzed by Manganese Porphyrin [Mn(TPP)OAc]

Manganese（Ⅲ） meso-tetraphenylporphyrin acetate [Mn（TPP）OAc] served as an effective catalyst for the oxidative decarboxylation of carboxylic acids with （diacetoxyiodo）benzene [PhI（OAc）2] in CH2CI2-H2O（95：5, volume ratio）. The aryl substituted acetic acids are more reactive than the less electron rich linear carboxylic acids in the presence of catalyst Mn（TPP）OAc. In the former case, the formation of carbonyl products was complete within just a few minutes with 〉97% selectivities, and no further oxidation of the produced aldehydes was achieved under these catalytic conditions. This method provides a benign procedure owing to the utilization of low toxic（diacetoxyiodo） benzene, biologically relevant manganese porphyrins, and carboxylic acids.

Separation of Aromatic Carboxylic Acids in IC and the Study on the Relationship Between Retention Behavior and Electrostatic Potential

A method has been developed for separation of 20 kinds of aromatic carboxylic acid using anion-exchange chromatography. A Dionex IonPac AS9-HC guard column （250mm×2mm） was used with a 9mmol/L sodium carbonate solution containing 50% （v/v） acetonitrile as eluent. A set of retention time data has been obtained using a conductivity detector DS6. Furthermore, geometrical optimization and electrostatic potential calculation of 20 kinds of aromatic carboxylic acid have been performed at the HF/6-31G＊ level of theory. A number of statistically-based parameters derived from molecular surface electrostatic potential have been obtained. Linear relationship between retention time and structural parameters has been established by multiple regression method. The result shows that parameters derived from electrostatic potential Vs ＋, Vs -, П together with the dipole moment μ can be well used to express the quantitative structure-retention time of this kind of aromatic carboxylic acid. Good predictive capability has also been demonstrated. The result has provided a framework which further proves the general applicability of this electrostatic potential parameter set to a great extent,and with which the ion chromatographic adsorption mechanism can be investigated.

Determination of Some CarbonylCarboxylic Acids Using Chemiluminescent Reaction of Ru (bipy)_3^(2+)-Ce (Ⅳ)

A coupled chemiluminescence method for the determination of some carhoxylic acids was devel-oped, based on their enhancement the chemiluminescence light emission of the reaction of tirs(2, 2'-bipyri-dine) ruthenium(Ⅱ) and Ce(Ⅳ) in sulfuric acid medium. The conditions for their determination were opti-mized. The following detection limits were obtained: oxalic acid, 2. 67×10-8 mol/L; propandioic acld, 1.20×10-6 mol/L; pyruvic acid, 1. 35 ×10-8 mol/L; citric acid, 5.10×10-8. mol/L; barbituric acid, 2.48×10-7,mol/L. The proposed method was successfully applied to determination or oxalic acid. The coupled chemilu-minescent reaction mechanism and rate equation are proposed.

Catalyst-free electrochemical S_(N)Ar of electron-rich fluoroarenes using carboxylic acids

Herein,an electrochemically driven catalyst-free nucleophilic aromatic substitution(S_(N)Ar)of electron-rich fluoroarenes with carboxylic acids as weak nucleophiles under mild conditions was reported.A series of highly valuable ester derivatives were obtained in a direct and rapid way.This transformation features commercially available reagents and an exceptionally broad substrate scope with good functional group tolerance,using cheap and abundant electrodes and completed within a short reaction time.Gram-scale synthesis and complex biorelevant compounds ligation further highlighted the potential utility of the methodology.The mechanistic investigations and density functional theory(DFT)calculations verified the feasibility of the proposed pathway of this transformation.

Visible-light-induced Synthesis of Organic Peroxides via Decarboxylative Couplings of Carboxylic Acids,Alkenes and tert-Butyl Hydroperoxide

Herein,we present a photoinduced,CeCl_(3)-catalyzed three-component decarboxylative reaction that couples carboxylic acids,alkenes and tert-butyl hydroperoxide for the formation of various organic peroxides.The ligand-to-metal charge transfer(LMCT)excitation mode allows the decarboxylative alkylation-peroxidation reaction to occur under mild conditions,and is well applicable to primary,secondary and tertiary carboxylic acids and styrene derivatives.

Deoxyfluorination of Carboxylic, Sulfonic, Phosphinic Acids and Phosphine Oxides by Perfluoroalkyl Ether Carboxylic Acids Featuring CF_(2)0 Units

The deoxyfluorination of carboxylic,sulfonic,phosphinic acids and phosphine oxides is a fundamentally important approach to access acyl fluorides,sulfonyl fluorides and phosphoric fluorides,thus the development of inexpensive,stable,easy-to-handle,versatile,and efficient deoxyfluorination reagents is highly desired.Herein,we report the use of potassium salts of perfluoroalkyl ether carboxylic acids(PFECA)featuring CF_(2)0 units as deoxyfluorination reagents,which are generated mainly as by-products in the manufacture of hexafluoropropene oxide(HFPO).The synthesis of acyl fluorides,sulfonyl fluorides and phosphoric fluorides can be realized via carbonic difluoride(COF_(2))generated in situ from thermal degradation of the PFECA salt.

Decarboxylative Fluorination of Arylcarboxylic Acids Promoted by ortho-Hydroxy and Amino Groups

A novel decarboxylative fluorination process has been developed for the synthesis of ortho-hydroxy/amino arylfluorides from salicylic acid analogs, in which the ortho-hydroxy/amino group plays an important role in the transformation. In addition, various arylfluorides are obtained in good to excellent yields under mild conditions.

Radical Decarboxylative Cyanomethylation of Aliphatic Carboxylic Acids and Uronic Acids via Vinyl Azide Cascade Fragmentation

A direct oxidative radical decarboxylative cyanomethylation of carboxylic acids is described using 3-azido-2-methylbut-3-en-2-ol as the carbon-centered radical acceptor.The transformation is applicable to structurally diverseα-amino acids,α-oxy acids,α-keto ac-ids,pentofuranuronic acids,and hexopyranuronic acids.The mechanistic investigations suggest that a radical process is involved in the transformation.This work provides a potential approach toβ-amino acid,5-deoxy-hexofuranose,and 6-deoxy-heptose con-structs of biological relevance.