Mild and Efficient Synthesis of Carboxylic Acid Anhydrides from Carboxylic Acids and Triazine Coupling Reagents

Abstract

Anhydrides of carboxylic acids were obtained in 53%–95% yield by treatment of appropriate carboxylic acids with 2‐chloro‐4,6‐dimethoxy‐1,3,5‐triazine (CDMT) or 2,4‐dichloro‐6‐methoxy‐1,3,5‐triazine (DCMT) in the presence of N‐methylmorpholine. It has been proved that synthesis proceeds via triazine active esters 3a,b, which are able to acylate carboxylate anion but not less nucleophilic carboxylic acid.     

Beyond Kolbe and Hofer–Moest: Electrochemical Synthesis of Carboxylic Anhydrides from Carboxylic Acids

Herein we report a conceptually new non‐decarboxylative electrolysis of carboxylic acids to obtain their corresponding anhydrides as highly valuable reagents in organic synthesis. All carbon atoms of the starting material are preserved in the product in an overall redox‐neutral reaction. In a broad substrate scope of carboxylic acids the anhydrides are generated with high selectivity, which demonstrates the versatility of the developed method. Beneficially, no dehydrating reagents are required in comparison to conventional methods and the synthesis is based on uncritical starting materials using graphite and stainless steel as very inexpensive and eco‐friendly electrode materials.     

Paradigms and Paradoxes: Aspects of the Energetics of Carboxylic Acids and Their Anhydrides

Making use of the enthalpies of formation of the well-established acetic acid and acetic anhydride, the energetics of other carboxylic acid anhydrides (with four or fewer carbons) are discussed. Some of these species are also well known, such as succinic and maleic anhydride. Others are less well known, such as ketene and carbon suboxide and even diatomic carbon and malonic anhydride. Still others are more evasive, such as the classical anhydrides of formic and oxalic acid.     

Synthesis of Aryl Ketones by Cross-Coupling Reaction of Arylboronic Acids with Carboxylic Anhydrides in Aqueous Phase

A highly efficient aqueous system of PdCl₂-catalyzed cross-coupling reaction of arylboronic acid with carboxylic anhydride (Suzuki-type reaction) without the use of phosphine ligands was developed. The reactions went smoothly in acetone/H₂O phase to give good yields of aryl ketones in short reaction times (1–3 h) at room temperature in air and were unaffected by the presence of electron-releasing and electron-withdrawing substituents in both the arylboronic acids and carboxylic anhydrides.     

Ligand‐Free Palladium‐Catalyzed Aerobic Oxidative Coupling of Carboxylic Anhydrides with Arylboronic Acids

We report a new, effective and environmentally friendly protocol for selective aerobic oxidative coupling of arylboronic acids with carboxylic anhydrides in the presence of ligand‐free palladium catalyst. The aryl benzoates are obtained in good to excellent yields.     

Thermochemical Study of Ethylene Glycol Mixtures with N,N-Disubstituted Amides of Carboxylic Acids

The enthalpies of mixing of N'N-disubstituted amides of formic, acetic acids with ethyleneglycol were considered in view of the data on the enthalpies of mixing of the same compounds with form-amide and water. The exothermicity of amide-ethylene glycol interactions results from the formation of heterocomponent H bonds stronger than the H bonds in ethylene glycol. Solvophilic solvation and solvophobic effects are much weaker in nonaqueous solutions with low concentrations of amides than in water.     

Mixed Anhydrides of Carboxylic and Trifluoroacetic Acids as Acylating Agents: I. Reactions of 3,5-Di-tert-butylbenzoyl Trifluoroacetate with tert-Butylphenols

The rate and pathway of reactions of 3,5-di-tert-butylbenzoyl trifluoroacetate with tert-butylphenols depend on the number and position of bulky substituents determining the extent of steric shielding of the phenolic hydroxyl.     

Four Gadolinium Coordination Compounds Derived from Various Tetrazole‐Containing Carboxylic Acids

Reactions of four different tetrazole‐containing carboxylic acids with GdCl₃ · 6H₂O, produced the coordination compounds, [Gd₄(pytza)₅(H₂O)₁₀(μ‐O) Cl] · 4H₂O · 2Cl ( 1 ) [pytza = 2‐(5‐(pyridine‐4‐yl)‐2H‐tetrazole‐2‐yl)acetato], [Gd(pztza)₂(H₂O)₆] · pztza · 3H₂O ( 2 ), [pztza = 2‐(5‐(pyrazin‐2‐yl)‐2H‐tetrazol‐2‐yl) acetato], [Gd(pmtza)₂(H₂O)₆]Cl · 2H₂O ( 3 ), [pmtza = 2‐(5‐(pyrimidyl‐2‐yl)‐2H‐tetrazol‐2‐yl) acetato], and Gd(tzpya)₂(H₂O)₅]Cl · 4H₂O ( 4 ) [tzpya = 2‐(4‐(5H‐tetrazol‐5‐yl)pyridin‐1(4H)‐yl) acetato]. The compounds were structurally characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. X‐ray diffraction analysis reveals that compound 1 displays a 2D single layered network and compounds 2 – 4 are mononuclear. Compounds 1 – 4 are self‐assembled to form 3D networks by hydrogen bonding interactions. Furthermore, the luminescent properties in the solid state at room temperature were investigated.     

High-Performance Thin-Layer Chromatography Combined with Densitometry for Quantitative Analysis of Phenolic Acids in Complex Mixtures

JPC – Journal of Planar Chromatography – Modern TLC - Protocatechuic acid and caffeic acid in plant extracts, both free and bound as glycosides and ester derivatives, have been...     

Cyclic Carboxylic Anhydrides as New Reagents for Formation of Chromone Ring

The propensity of cyclic carboxylic anhydrides to undergo ring‐opening was exploited in a reaction with 2'‐hydroxy‐α‐heteroarylacetophenones leading to the formation of chromones. New simple method was developed for the synthesis of 2‐(ω‐carboxyalkyl)‐3‐heteroarylchromones without protecting either the phenolic or the carboxylic groups. Treatment with hydrazine led to the formation of 3(5)‐(ω‐carboxyalkyl)‐5(3)‐(2,4‐dihydroxyphenyl)‐4‐heteroarylpyrazoles.     

The Borderline between Reactivity and Pre‐reactivity of Binary Mixtures of Gaseous Carboxylic Acids and Alcohols

By mixing primary and secondary alcohols with carboxylic acids just before the supersonic expansion within pulsed Fourier transform microwave experiments, only the rotational spectrum of the ester was observed. However, when formic acid was mixed with tertiary alcohols, adducts were formed and their rotational spectra could be easily measured. Quantum mechanical calculations were performed to interpret the experimental evidence.     

Microwave-Assisted Cross-Coupling Reaction of Sodium Tetraphenylboratewith Carboxylic Anhydrides Catalyzed by Palladium

Cross-coupling processes of aryl or alkenyl halides with organometallic compounds of main group elements cat alyzed by palladium complexes have been found extensive use in organic synthesis. These cross-coupling reactions offer a powerful tool for the formation of carbon-carbon bonds. [1] The Suzuki-Miyaura cross-coupling reaction has been employed for the synthesis of ketone as well.     

羧酸类化合物的结构和萃取性能的相关性

应用量子化学参数研究羧酸类化合物的结构与其萃取性能的相关性,并将二维结构参数应用到三维构效关系研究中,从而有效地改善了CoMFA法的结果,用pK_a值来表征羧酸类化合物的萃取性能.     

Microwave-Assisted Esterification of Diverse Carboxylic Acids and Chiral Amino Acids

A facile and efficient synthetic method of esters from their corresponding carboxylic acids and amino acids is described. The esterification reaction of carboxylic acids and amino acids could be greatly accelerated under microwave irradiation because the reactions described in this article took place in only 5 min with almost quantitative yields, and distinct acidity of catalytic acids was well tolerated. Unlike the racemation problem in microwave-assisted N-acylation reactions, the esters of chiral amino acids could be achieved with retention of configuration under this condition.