Thiophenecarboxylic Acid Research Articles

Thermochemical properties of three 2-thiophenecarboxylic acid derivatives

The standard ( p ∘ = 0.1 MPa) molar enthalpies of formation, in the crystalline state, of the three thiophenecarboxylic acid derivatives, at T = 298.15 K, were derived from the standard massic energies of combustion, measured by rotating-bomb combustion calorimetry. The Knudsen mass loss effusion method was applied to determine the temperature–vapour pressure dependence, from which the standard molar enthalpies of sublimation, at T = 298.15 K, were derived by fitting data to the Clausius–Clapeyron equation. The values obtained were: Compounds - Δ f H m ∘ (cr)/(kJ · mol −1) Δ cr g H m ∘ /(kJ · mol −1) 3-Methyl-2-thiophenecarboxylic acid 393.6 ± 1.7 98.0 ± 0.4 5-Methyl-2-thiophenecarboxylic acid 395.7 ± 1.6 101.9 ± 0.3 5-Acetyl-2-thiophenecarboxylic acid 547.8 ± 1.8 123.5 ± 0.6 The standard ( p ∘ = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, were derived from the experimental results and the enthalpy of isomerisation between 3-methyl- and 5-methyl-2-thiophenenecarboxylic acids was calculated. Moreover, the results are compared with the analogue benzene derivatives and discussed in terms of molecular structure.

Synthesis and Characterization of Polyacetylene with Side-chain Thiophene Functionality

A new polyacetylene derivative with electroactive thiophene substituent, namely poly(2-methylbut-2-enyl thiophene-3-carboxylate) was synthesized and characterized. For this purpose, novel acetylene monomer was synthesized by the reaction of 3-thiophenecarboxylic acid with propargyl bromide and polymerized with a Rh catalyst to give the corresponding polymer. The chemical structure of the polymer was characterized to comprise the conjugated backbone and electroactive thiophene side group. UV spectral changes of the polymer with temperature were also studied. The polymer exhibited better thermal stability than the unsubstituted polyacetylenes.

Regioselective C−H Functionalization Directed by a Removable Carboxyl Group: Palladium-Catalyzed Vinylation at the Unusual Position of Indole and Related Heteroaromatic Rings

The palladium-catalyzed oxidative vinylation of indole-3-carboxylic acids with alkenes effectively proceeds via directed C-H functionalization and decarboxylation to produce the corresponding 2-vinylated indoles. Similarly, pyrrole-, furan-, and thiophenecarboxylic acids also undergo decarboxylative vinylation.

Synthesis and Characterization of Sulfur Containing Dextran- and β-Cyclodextrin Derivatives

Sulfur containing dextran and β-cyclodextrin derivatives were synthesised as alternitive coating materials for gold surfaces. The esterification of the carbohydrates with thiophene carboxylic acids and α-lipoic acid was carried out in DMSO by in situ activation of the acids with N,N’-carbonyldiimidazole. The thiophene carboxylic acids vary in the position of the sulfur atom and the spacer between the thiophene and the carboxylic group. DS values ranging from 0.44 to 2.04 were accessible depending both on the carbohydrate and the acid used. Insoluble derivatives were obtained by the conversion of α-lipoic acid with the carbohydrates. The structure of the derivatives soluble in DMSO and DMF was examined by IR- and NMR spectroscopy. Furthermore, subsequent acylation reveals a useful tool for the determination of the degree of substitution of the thiophene derivatives additionally to elemental analysis.

Degradation of dibenzothiophene and carbazole by Arthrobacter sp. P1-1

Arthrobacter sp. P1-1 was isolated from a polycyclic aromatic hydrocarbon (PAH)-contaminated site in Hilo, HI, USA. This strain can degrade approximately 82% of dibenzothiophene (DBT) (40 mg l−1) and 57% of carbazole (CBZ) (40 mg l−1) in 14 days incubation. Dibenzothiophene-5,5′-dioxide was formed from sulfur oxidation of DBT. Dibenzothiophene diols that were transformed from 1,2- and 3,4-dioxygenations of DBT underwent ortho- and meta-ring cleavages to produce benzo[b]thiophene-2,3-dicarboxylic acid and hydroxyl-benzo[b]thiophene carboxylic acid, respectively. These products were converged into benzo[b]thiophene-2,3-diol, which was further transformed to 2,2′-dithiosalicylic acid via 2-mercaptobenzoic acid. These results indicate that strain P1-1 has diverse lateral dioxygenase systems and subsequent metabolic enzyme systems. The five detected CBZ metabolites by strain P1-1 were 4-(3-hydroxy-1H-indol-2-yl)-2-oxobut-3-enoic acid, 2-(2-carboxy-vinyl)-1H-indole-3-carboxylic acid, pyrido[1,2-a]indole-6,10-dione, indole-2,3-dicarboxylic acid, and 2-aminobenzoic acid. The results suggest that CBZ degradation underwent 3,4-dioxygenation followed by ortho- and meta-ring cleavage.

Ulcera del Buruli: la "nuova lebbra" Africana. Isolamento e identificazione di M. ulcerans in prelievi bioptici provenienti da pazienti del Benin

Buruli ulcer, caused by Mycobacterium ulcerans, a slow growing mycobacterium which classically infects the skin and the subcutaneous tissues generating indolent ulcers, is, after tuberculosis and leprosy, the third most common mycobacterial infection and has emerged as an important cause of human disease in at least 32 tropical and subtropical countries.The disease initially manifests a painless swelling in the skin and progresses to skin ulceration. Because of the lack of a specific vaccine and the inefficacy of antibiotic therapies, the current treatment is surgical excision. Early diagnosis and treatment prevent complications and therefore, a prompt and accurate diagnosis is crucial, but difficult to perform in countries with limited resources. In this paper we describe the mycobacteriological diagnosis on samples obtained from patients who underwent plastic-reconstructive surgery in a hospital in Zinvie, Benin (West Africa). M. ulcerans was isolated from 19/32 subjects at the mycobacteriology laboratory of the Institute of Hygiene, University of Bari, Italy, 10-15 days after sampling. The identification of M. ulcerans was performed with a panel of tests for conventional identification, including biochemical analyses (niacin, nitrate reduction, catalase at 68°C, Tween hydrolysis, and urease), cultures (growth at 32, 37, and 45°C), and inhibition studies (tolerance of 5% NaCl and thiophenecarboxylic acid) as well as with INNO-LiPA MYCOBACTERIA v2 and confirmed with Chromatographic Analysis of Cell Wall Mycolic Acid (high-performance liquid chromatography). Our results demonstrate that, even on samples collected in distant sites and analyzed after 10-15 days, the conventional phenoptype identification confirmed by molecular testing and HPLC resulted in an accurate identification of such a devastating and relatively rare mycobacterium as M. ulcerans which had never been previously isolated in Italy.

Biphenyl‐4‐ylcarbamoyl Thiophene Carboxylic Acids as Potent DHODH Inhibitors.

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Biphenyl-4-ylcarbamoyl thiophene carboxylic acids as potent DHODH inhibitors

A previously discovered DHODH inhibitor series was further improved by replacing the cyclopentene ring by aromatic heterocycles. Different isomers of these compounds were prepared by the directed ortho-metallation procedure. The compounds are more active than the corresponding cyclopentene analogs and show potent effects on PBMC’s proliferation.

Structural and electronic effects induced by carboxylic acid substitution in isomeric 2,2′-bithiophenes and oligothiophenes: A computational study

The structural and electronic properties of carboxylic acid-substituted 2,2′-bithiophenes have been examined using quantum mechanical methods based on density functional theory. Calculations at the B3PW91/6-31+G(d,p) level were performed on 2,2′-bithiophene-4,4′-dicarboxylic acid, 2,2′-bithiophene-3,4′-dicarboxylic acid and 2,2′-bithiophene-3,3′-dicarboxylic acid, different arrangements being additionally considered for the carboxylic acid substituents of each isomer. The energy gap calculated for 2,2′-bithiophene-3,4′-dicarboxylic acid was about 0.15 eV smaller than that predicted for unsubstituted 2,2′-bithiophene. Additional calculations were performed on oligothiophenes containing n carboxylic acid substituted thiophene rings, n ranging from 2 to 7. The results, which allowed to estimate the band gap for the corresponding poly(thiophene carboxylic acid)s, indicated that the introduction of carboxylic acid substituents at polythiophene produces a very small increase in the ε g gap.

New method for the synthesis of 2-thiophenecarboxylic acids in the presence of V-, Fe-, or Mo-containing catalysts

Thiophenecarboxylic acid and its derivatives were synthesized by the reaction of thiophenes with the CCl4-CH3OH-catalyst system in total yields of 44-85%. The probable scheme of the reaction involves successive oxidation of methanol with tetrachloromethane to methyl hypochlorite and formaldehyde. Under the action of the latter, thiophene undergoes oxymethylation, giving rise to 2-oxymethylthiophene, which is oxidized with CH3OCl to 2- thiophenecarboxylic acid. In the presence of an excess of CH3OH, the latter is subjected to esterification. It was found that Fe(acac)3, VO(acac)2, and Mo(CO)6 are the catalysts of choice for this reaction.

Thermophysical, crystalline and infrared studies of the 2- and 3-thiophenecarboxylic acids

A thermophysical study by differential scanning calorimetry (DSC) for the 2- and 3-isomers of thiophenecarboxylic acid, in the temperature intervals between T=268 K and their respective melting temperatures has been carried out, and enhancements in the heat capacity curves were observed. The supramolecular structure of both compounds was analysed by X-ray crystallography and IR spectroscopy to determine which structural modifications take place in the temperature range at which the heat absorption occurs. Changes in bands assigned mainly to δ(OH) + ν(CO), δ(CH) + ν(CS) and out of plane CH vibrations point to structural modifications taking place in the temperature range at which the heat absorption occurs. All those groups are involved in the weak CH⋯O or CH⋯S contacts that form the crystal three-dimensional network and so it can be concluded that changes in these H-bond strength, are responsible for the small heat absorptions founded in the heat capacity curves.

Synthesis of New Cyano-Substituted bis-Benzothiazolyl Arylfurans and Arylthiophenes

The new compounds 2-[4-(6-cyanobenzothiazol-2-yl)phenyl]-5-(6-cyano- benzothiazol-2-yl)furan (6a) and 2-[4-(6-Cyanobenzothiazol-2-yl)phenyl]-5-(6-cyano- benzothiazol-2-yl)thiophene (6b) were synthesized by multi-step reactions from the corresponding 2-furan and 2-thiophene carboxaldehydes (route A), as well as from 2- furan and 2- thiophene carboxylic acids (route B). Route B involves one less step than route A, but the overall yields of the reactions are considerably lower.

Synthesis and Transformations of 2-Substituted Tetrahydro-4 H -benzo[4,5]thieno[2,3-d][1,3]oxazines and 2,3-Disubstituted Hexahydrobenzo[4,5]thieno[2,3-d]pyrimidines

3-(4-Oxo-5,6,7,8-tetrahydro-4 H -benzo[4,5]thieno[2,3-d][1,3]oxazin-2-yl)propanoic acid and its ethyl ester 6a , b have been prepared via succinoylation of ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate 1 , followed by ester hydrolysis, selective esterification, and acetic anhydride induced cyclization of the thiophenecarboxylic acid derivatives 3 , 5 . Reaction of 1 with diethyl malonate gave the malonic acid diamide 7 , which on ester hydrolysis followed by acetic anhydride induced water elimination furnished the 2-substituted 4 H -benzo[4,5]thieno[2,3-d][1,3]oxazine derivative 10 in high yield. A series of new benzo[4,5]thieno[2,3-d]pyrimidines 11-19 , which bear a propanoic acid substituent in the 2-position and an amino, aryl, aminosugar, and arylmethylideneamino-substituents in the 3-position have been prepared via the reaction of 6a , b with hydrazine hydrate or aromatic amines followed by treatment with aromatic aldehydes, isatin, or aldoses. The aldimines 18a-d underwent unprecedented acid catalyzed tandem cyclization-transannular aldehyde extrusion into octahydro-1 H -benzo[4',5']thieno[2',3':4,5]pyrimido[1,2-b]pyridazines 21 . Two other unequivocal approaches for 21 also have been explored, either by treatment of the amino acid derivative 11 with thionyl chloride or by thermal cyclization of the amino ester derivative 12 .

Experimental and Computational Thermochemistry of 2- and 3-Thiophenecarboxylic Acids

The enthalpies of combustion and sublimation of 2- and 3-thiophenecarboxylic acids were measured and the gas-phase enthalpies of formation at 298.15 K were determined. Standard ab initio molecular orbital calculations at the G2(MP2) and G2 levels were performed, and a theoretical study on molecular and electronic structures of the studied compounds has been carried out. Calculated enthalpies of formation using atomization and isodesmic bond separation reactions are compared with the experimental data. From experimental and theoretical results it seems that 3-thiophenecarboxylic acid is slightly more stable than the 2-isomer. A comparison of substituent effect of the carboxylic group in benzene and thiophene rings has been made.

Identification of compound classes in soil and peat fulvic acids as observed by electrospray ionization tandem mass spectrometry.

Soil and peat fulvic acids obtained from the International Humic Substances Society were fractionated by their solubility in methanol and analyzed by electrospray ionization tandem mass spectrometry. Precursor and product ion experiments produced mass spectra that indicated the presence of benzene, phenol, dihydroxy benzene, furan and thiophene carboxylic acids. Standards were used to substantiate the fragmentation patterns observed in the product ion spectra of the fulvic acid samples. This study makes significant progress into the direct identification of individual compounds in humic substances using a non-degradation technique.

Single-Molecule Magnets: Magnetic Properties of [Mn 12 ] Complexes with Sulfer-Containing Carboxylates

Magnetic properties of [Mn 12 ] complexes with sulfer-containing carboxylates, [Mn 12 O 12 (tha) 16 (H 2 O) 4 ] ( 2 ) and [Mn 12 O 12 (tpc) 16 (H 2 O) 4 ] ( 3 ) (thaH= trans -3-(3-thienyl)acrylic acid, tpcH=2-thiophenecarboxylic acid), are investigated. Both complexes showed frequency-dependent out-of-phase signals in ac susceptibility, indicating they are single-molecule magnets (SMMs). The energy barrier heights for reversing its magnetization from spin "up" to spin "down" are estimated to be 67 K and 68 K for 2 and 3 , respectively. single-molecule magnet [Mn 12 ] complex ac magnetic susceptibility thiophene carboxylic acids

Supramolecular assemblies with dithieno[3,2-b;2′,3′-d]thiophenes and other conjugated thiophene-containing π-systems

We report the synthesis of a new type of supramolecular assembly based on hydrogen-bonded complexes between conjugated or fused thiophenecarboxylic acids and a tris(imidazoline) base (1).

Fused-ring and linking group effects of proton donors and acceptors on simple H-bonded liquid crystals

Two fused-ring structures, 6-decyloxy-2-naphthoic acid C10ONA (3) and 6-dodecyloxyisoquinoline IS (8), were synthesized and utilized as proton donor and acceptor moieties to construct a series of simple mesogenic supramolecules. The other complementary hydrogen-bonded (H-bonded) moieties are benzoic acids, thiophenecarboxylic acid and pyridines containing different alkyl chain lengths connected by ether and ester linkages, i.e. 4-alkoxybenzoic acid C n OBA (1), terephthalic acid monoalkyl ester C n COOBA (2), 2,5-thiophenedicarboxylic acid monodecyl ester C10COOTHA (4), 4-alkoxypyridine C n OP (6) and isonicotinic acid alkyl ester C n COOP (7). Several series of simple mesogenic supramolecular dimers were constructed from 1:1 molar ratios of proton donors (C n OBA, C n COOBA, C10ONA and C10COOTHA) and proton acceptors (IS, C n OP and C n COOP), though the proton acceptor C n COOP induced phase separation in all complexes. In order to investigate their fused-ring and linking group effects on the mesogenic properties of the H-bonded complexes, analogous simple supramolecular structures are compared. Supramolecular architecture and the distinct mesomorphism of these simple H-bonded liquid crystalline materials were confirmed by polarizing optical microscopy, DSC and powder X-ray diffraction experiments.

Molecular orientation with visible light: Reflectance-anisotropy spectroscopy of 3-thiophene carboxylate on Cu(110) surfaces

We present reflectance-anisotropy spectroscopy data for the adsorption of 3-thiophene carboxylic acid on the clean and $\mathrm{O}(2\ifmmode\times\else\texttimes\fi{}1)/\mathrm{C}\mathrm{u}(110)$ surfaces, which demonstrates the sensitivity to orientation parallel and perpendicular to the surface. Electronic structure calculations were performed to clarify the bonding and assign RAS transitions.

ChemInform Abstract: Preparation of Polydeuterated Phenylpropanoic Acids (cf. (II), (IV)) by the Desulfurization of Halogenated Benzo(b)thiophenecarboxylic Acids with Nickel‐ and Cobalt‐Aluminum Alloys in Alkaline D2O.

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