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.

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.

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.

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.

Nanostructured bimetallic Zn/Co in N-doped carbon as an efficient catalyst for the alcohol dehydrogenation to carboxylic acids under solvent-free conditions

The catalytic alcohol dehydrogenation to carboxylic acids has been demonstrated as an atom-economic and environmental-friendly synthetic method.However,the reported catalysts either require relatively complicated synthesis or exhibit high activity only in the presence of a solvent.Therefore,it is still in high demand to obtain catalysts that feature facile synthesis and perform well even without any solvent.Herein,a series of nanostructured bimetallic Zn/Co species embedded in N-doped hierarchical porous carbon were fabricated in a facile and green manner.More significantly,the best-performing material(Zn/Co@NC-800)was identified as the first heterogeneous catalyst to enable this transformation under solvent-free conditions.Moreover,the as-prepared composites were comprehensively investigated to de-termine their structural and morphological properties,which rationalized the superiority of Zn/Co@NC-800 over the other synthesized materials.Further studies signified that Co sites(both Co^(0)and Co^(2+))and N species(mainly pyridinic N)were probably involved in this process,functioning as the Lewis acid site and basic site,respectively.Hopefully,this study could provide a simple and sustainable method for carboxylic acid synthesis.

Iron-Catalyzed Amide Bond Formation from Carboxylic Acids and Isocyanates

We describe an iron-catalyzed amide bond formation from readily available carboxylic acids and isocyanates.This method utilizes an abundant and biocompatible iron catalyst and easily accessible starting materials,generates CO_(2) as the only byproduct,and features broad substrate scopes with good functional group compatibility.Therefore,it provides a cost-effective and practical protocol to access a diverse variety of amides.

Chiroptical coassemblies between organic carboxylic acids and amino acid derivatives with C_(3)-symmetry

Benzimidazole amino acid derivatives behave as supramolecular hosts to include organic acids via complementary hydrogen bonding whereby supramolecular chirality and chiroptical properties could be manipulated.Organic acids enhanced the chiral assembly that showed tunable circularly polarized luminescence with high dissymmetry g-factors at 10^(-2)grade.

A review of anodic catalysts and their application in(non-)Kolbe electrocatalytic decarboxylation of carboxylic acids

Biomass,as the exclusive and abundant organic resources,is considered to be the promising renewable resource.Carboxylic acids are one of the many compounds that can be obtained from raw biomass.Decarboxylation of carboxylic acids into fuels and chemicals via electrochemical method at mild reaction condition has been studied for many years.The(non-)Kolbe reaction,one of the oldest organic electrochemical reactions,is the decarboxylation of carboxylic acids to produce alkanes,alcohols,esters,etc.And electrode materials influence the production of electrocatalytic decarboxylation products from carboxylic acids.Therefore,this work mainly reviews the recent advances in applications of anodic materials for(non-)Kolbe electrocatalytic decarboxylation of carboxylic acids.It discusses the reaction mechanism of(non-)Kolbe electrolytic reaction,and the electrocatalytic oxidation of carboxylic acid using different electrodes and electrolytic systems to synthesize fuels and chemicals.Also,various types of electrode catalysts,such as Pt-based catalysts,C-based catalysts,and other catalysts,are introduced in detail.Finally,the challenges and future trends of the(non-)Kolbe reaction of carboxylic acids are presented.This review found that platinum-based electrocatalysts proved to be the most promising catalysts at present.And in recent years,a variety of synthesis methods have been developed to synthesize small size and high-performance noble metal based amorphous catalysts.Another approach is to study catalysts without platinum electricity,such as Ru,Ir,Ti and carbon materials.The review is helpful in understanding and know the anodic materials and their application in(non-)Kolbe electrocatalytic decarboxylation of carboxylic acids for the readers.

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.

Copper-catalyzed amide bond formation from formamides and carboxylic acids

A highly efficient copper-catalyzed approach to form amide bonds from formamides and carboxylic acids was developed. This protocol shows broad substrate scopes and high yields in the presence of 1 mol% catalyst and 4.0 equiv, formamides.