Anhydrous Potassium Carbonate Research Articles

Base catalyzed reaction of ethyl thioglycolate with β-aryl-β-(methylthio) acroleins: a general method for the synthesis of 2-carbethoxy-5-substituted/4,5-annulated thiophenes in high overall yields

(Methylthio) acroleins 1a–m were shown to be stable unlike their counterpart the chloroacroleins and their efficacy as 1,3-dielectrophilic properties have now been examined successfully in this work. They are shown to react with ethyl thioglycolate in the presence of anhydrous potassium carbonate in boiling ethanol to yield the corresponding 5-substituted/4,5-annulated-2-carbethoxy thiophenes in 70–80% overall high yields.

Synthesis, molecular structure and spectroscopic studies of some new quinazolin-4(3H)-one derivatives; an account on the N- versus S-Alkylation

A new series of N- and S-alkylated products of 3-aryl-1H,3H-quinazolin-2,4-dione and 3-aryl-2-mercapto-3H-quinazolin-4-one, respectively, were prepared in good yields via efficient nucleophilic substitution reaction of the SH and NH substrates with methyl iodide, ethyl bromoacetate, allyl bromide, propagyl bromide, 2-bromoethanol, 1,3-dibromopropane or phenacyl bromide in DMF as a solvent and anhydrous potassium carbonate. The quinazolin-2,4-dione favored the N-alkylation while the 2-mercapto-3H-quinazolin-4-one goes via the S-alkylation. DFT reactivity studies showed that the former have the N-site with higher nucleophilicity compared to the O-site. In contrast, the S-site is the more nucleophilic centre than the N-atom of the latter. The structures of the synthesized products have been established on the basis of their melting point (m.p), IR and 1HNMR data. The molecular structures of the products were calculated using the DFT B3LYP/6-311G(d,p) method. The electronic and spectroscopic properties (Uv–Vis and NMR spectra) were calculated using the same level of theory. The chemical reactivity descriptors that could help to understand the biological activity of the products are also predicted.

Synthesis and Antiproliferative Activities of Benzimidazole-Based Sulfide and Sulfoxide Derivatives.

The design, synthesis, and in vitro antiproliferative activity of a novel series of sulfide (4a–i) and sulfoxide (5a–h) derivatives of benzimidazole, in which different aromatic and heteroaromatic acetamides are linked to benzimidazole via sulfide (4a–i) and sulfoxide (5a–h) linker, are reported and the structure-activity relationship is discussed. The new derivatives were prepared by coupling 2-(mercaptomethyl)benzimidazole with 2-bromo-N-(substituted) acetamides in dry acetone in the presence of anhydrous potassium carbonate. With very few exceptions, all of the synthesized compounds showed varying antiprolific activities against HepG2, MCF-7, and A549 cell lines. Compound 5a was very similar in potency to doxorubicin as an anticancer drug, with IC50 values 4.1 ± 0.5, 4.1 ± 0.5, and 5.0 ± 0.6 µg/mL versus 4.2 ± 0.5, 4.9 ± 0.6, and 6.1 ± 0.6 µg/mL against HepG2, MCF-7, and A549 cell lines, respectively. In contrast, none of the compounds showed activity against human prostate PC3 cancer cells. Additionally, the sulfoxide derivatives were more potent than the corresponding sulfides.

CRYSTAL STRUCTURE OF (2-METHYL-PHENOXY)-ACETOHYDRAZIDE

The title compound, (2-methyl-phenoxy)-acetohydrazide, was synthesized by refluxing compounds o -cresol, ethyl chloroacetate and anhydrous potassium carbonate in the presence of dry acetone. The compound crystallizes in the monoclinic crystal system with space group P2 1 /n having unit cell parameters: a = 11.5460(2), b = 6.86700(10), c = 12.7506(3)A, β = 110.022(2)o and Z = 4 . The crystal structure was solved by direct method using single crystal x-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R- value of 0.0377 for 1619 observed reflections. In the crystal structure, molecules are linked into infinite two-dimensional networks by the N–H···N and N–H···O, C−H…O and C−H…π type of hydrogen bonds.

Synthesis and properties of novel 9,9-diphenyl xanthene-based poly(aryl ether ketone)s with methyl substituents

A new bisphenol, 9,9-bis(4-hydroxy-3-methylphenyl)xanthene, was synthesized via a one-pot, two-step synthetic procedure in good yield and used for polymerization with difluorinated aromatic ketones in tetramethylene sulfone in the presence of anhydrous potassium carbonate to form several aromatic poly(ether ketone)s (PEKs) with 9,9-diphenylxanthene moieties and methyl substituents. The newly synthesized high-molecular-weight PEKs having number-average molecular weights in the range of 20,500–25,600 g mol−1 with the polydispersity index ranging from 1.9 to 2.1 were all amorphous and showed high glass transition temperatures in the range of 194–229.8°C, and the temperatures at the 5% weight loss were in the range of 420–445°C with char yields above 60% at 600°C under nitrogen atmosphere. All new PEKs are soluble in polar aprotic solvents, such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, chloroform, pyridine, m-cresol, and tetrahydrofuran, and could form transparent, strong, and flexible films with tensile strengths of 66–74 MPa, Young’s moduli of 2.47–2.77 GPa, and elongations at break of 8–14%. In addition, these polymers had high transparency with an ultraviolet–visible absorption cutoff wavelength in the 352–356 nm range and low moisture absorption in the range of 0.41–0.56%.

Synthesis, electrochemistry and In situ spectroelectrochemistry of novel tetra dimethyl 5-oxyisophthalate substituted Co(II), Mn(III), and μ-oxo-dimer Fe(III) phthalocyanines

In this study, peripheral and non-peripheral tetra dimethyl 5-oxyisophthalate substituted cobalt(II), manganese(III) and μ-oxo-dimer Fe(III) phthalocyanines were synthesized by the reaction of dimethyl 5-hydroxyisophthalate with 1,2-dicyano-4-nitrobenzene/1,2-dicyano-3-nitrobenzen in dry N,N-dimethylformamide in the presence of anhydrous potassium carbonate. All purified phthalocyanine compounds were characterized by using FT-IR, UV–visible, MALDI-TOF mass spectrometry and elemental analyses results. Electron transfer properties of all novel cobalt(II), manganese(III) and μ-oxo-dimer Fe(III)phthalocyanine complexes were investigated by voltammetric and in situ spectroelectrochemical measurements in nonaqueous solution medium. Complexes were observed to display both metal-based and phthalocyanine ring-based reduction and oxidation electron transfer processes.

Facile synthesis of novel poly(arylene ether)s containing N-arylenebenzimidazolyl groups via C–N/C–O coupling reaction

This article presents a convenient polymerization route to synthesize poly(arylene ether)s containing N-arylenebenzimidazolyl groups. The novel polymers were prepared by a catalyst-free nucleophilic substitution reaction, in which the N–H and O–H sites were removed from 2-(2-hydroxyphenyl)-1H-benzimidazole with different activated difluorides containing carbonyl groups in sulfolane. The reaction was carried out in the presence of anhydrous potassium carbonate at 210°C. The structures of the polymers were characterized using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and elemental analysis. The results show good agreement with the proposed structure. All resulting polymers show essentially amorphous patterns. Moreover, differential scanning calorimetry and thermogravimetric measurements show that the polymers have high glass transition temperatures (>209°C), good thermostability, and high decomposition temperatures (>425°C). Furthermore, the polymers also exhibit excellent solubility in common organic solvents.

Synthesis and Antimicrobial Activity of Some New Chalcones Containing Benzofuran and Benzofuran Schiff Bases

Benzofuran nucleus frequently occurs in natural products. In the present course of study an attempt is made for synthesis of new Benzofuran derivatives. 5-chloro-2-hydroxy acetophenone 2 was prepared by the Fries rearrangement with anhydrous aluminium chloride at 1300c for 3 hrs. The compound 2 was treated with chloroacetone in presence of anhydrous acetone and potassium carbonate gave 5-chloro-3-methyl-2-acetyl Benzofuran 3. Compound 3 underwent condensation with aromatic aldehyde and aromatic amines to furnished chalcone and Schiff derivatives 4a-e and 5a-e respectively. The synthesized compounds were screened for their antimicrobial activities.

Synthesis and Characterization of Novel 1,3-Thiazole and 2-Amino-1,3,4-Thiadiazole Derivatives

<p>Thiosemicarbazone derivatives <strong>3a–e</strong> were synthesized by the reaction of various aldehydes<strong> 1a–e</strong> with 4-methyl thiosemicarbazide <strong>2</strong> in 78% to 90% yield. Then, the thiazole moieties of the target materials <strong>5a–e</strong> were obtained in high yields (71–93%) using the Hantzsch reaction utilizing thiosemicarbazone derivatives <strong>3a–e</strong> with ethyl-2-chloroacetoacetic ester. The substituted nitrile derivatives <strong>7a–e</strong> were obtained in moderate to high yield (58–84%) from the reaction of compounds <strong>5a–e</strong> with chloroacetonitrile by the nucleophilic aliphatic substitution reaction in the presence of anhydrous potassium carbonate. Finally, substituted 2-amino-1,3,4-thiadiazole compounds <strong>9a–e</strong> were obtained in moderate to good yields (51–62%) from the reaction of thiosemicarbazide with substituted nitrile derivatives <strong>7a–e</strong>. As a result, compounds that all share a high disposition for biological activities were obtained. The structures of the newly synthesized compounds were confirmed by IR, <sup>1</sup>H NMR, <sup>13</sup>C NMR, elemental analysis, and mass spectrometric techniques.</p>

Synthesis of novel poly(N-arylenebenzimidazole)s containing biphenyl groups via N-C coupling reaction

A new bis(benzimidazolyl) monomer containing biphenyl group, 4,4′-bis(2-benzimidazolyl) diphenyl, was successfully synthesized from 4,4′-biphenyldicarboxylic acid and 1,2-phenylenddiamine. The corresponding biphenyl-containing poly(N-arylenebenzimidazole)s were prepared using C-N coupling reaction that removed the N-H sites from the novel bis(benzimidazolyl) derivative with activated aromatic difluorides in sulfolane. The reaction was carried out at 210°C in the presence of anhydrous potassium carbonate. All resulting polymers showed essentially amorphous patterns. This was consistent with the calculated results. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>253°C) and good thermal stability with high decomposition temperatures (>457°C). These novel polymers also showed easy solubility.

Synthesis of N-substituted poly(benzimidazole ketone ketone)s containing pyridine rings

Poly( N-arylenebenzimidazole ketone ketone pyridine)s have been prepared via N–C coupling reaction that removed the N–H sites from the novel bis(benzimidazoyl) derivatives with activated aromatic difluorides in sulfolane. The reaction was carried out at 210°C in the presence of anhydrous potassium carbonate. The structures of the polymers were characterized by means of Fourier transform infrared and proton nuclear magnetic resonance spectroscopies and elemental analysis. All resulting polymers showed essentially amorphous patterns. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>179°C), good thermostability, and high decomposition temperatures (>401°C). These novel polymers also showed easy solubility.

Synthesis and characterization of new poly(aryl ether ketone)s bearing (4-phenoxyphenyl)triphenylmethane moieties

1,1-Bis(4-hydroxyphenyl)-1-(4-phenoxyphenyl)-1-phenylmethane (BHPPPPM), a new bisphenol monomer, was synthesized with 65% yield from 4-benzoyl diphenyl ether in a one-pot, two-step synthetic procedure. Four new poly(aryl ether ketone)s (PAEKs) bearing (4-phenoxyphenyl)triphenylmethane moieties were prepared from BHPPPPM with four difluorinated aromatic ketones via a nucleophilic substitution reaction. The polycondensation proceeded in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the new PAEKs in nearly quantitative yields with inherent viscosities of 0.60–0.78 dL g−1. The resulting PAEKs having number-average molecular weights in the range of 29,500–34,200 g mol−1 with the polydispersity index ranged from 1.94 to 2.01 are all amorphous and show high glass transition temperatures ranging from 174°C to 196°C, excellent thermal stability, and the temperatures at the 5% weight loss are over 500°C with char yields above 60% at 700°C under nitrogen atmosphere. These new PAEKs are all soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone and N,N′-dimethylacetamide and could also be dissolved in chloroform and tetrahydrofuran. All the polymers formed transparent, strong, and flexible films with tensile strengths of 78–85 MPa, tensile moduli of 1.9–2.4 GPa, and elongations at break of 7–10%.

The Thermal Instability of 2,4 and 2,6-N-Alkylamino Disubstituted and 2-N-Alkylamino Substituted Nitrobenzenes in Weakly Alkaline Solution: sec-Amino Effect.

We report herein the preparation of two families of secondary amines by the reactions of two equivalents of monoamines with either 2,4 or 2,6-difluoronitrobenzenes in N,N-dimethylacetamide in the presence of anhydrous potassium carbonate, as precursors of biologically important nitric oxide donating N-nitrosamines. In both instances, these compounds could be prepared in quantitative yield when the reaction temperature was held below 130°C. Above this reaction temperature, an unexpected cyclization reaction between the nitro and newly formed adjacent secondary amine group leads to the formation of benzimidazole or quinoxaline rings in low yields. Reasonable reaction mechanisms for the cyclization reaction are proposed.

Synthesis of 3‐Acetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐one Derivatives

The cyclization of aryl ketone anilides 3 with diethyl malonate to affords 4‐hydroxy‐6‐phenyl‐6H‐pyrano[3,2‐c]‐pyridin‐2,5‐diones 4 in good yields. 3‐Acetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐ones 5 are obtained by ring‐opening reaction of 4‐hydroxy‐6‐phenyl‐6H‐pyrano[3,2‐c]‐pyridin‐2,5‐diones 4 in the presence of 1,2‐diethylene glycol. The reaction of 3‐acetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐ones 5 with hydroxylamine hydrochloride produces 4‐hydroxy‐3‐[N‐hydroxyethanimidoyl]‐1‐phenylpyridin‐2(1H)‐ones 6 from which 3‐alkyloxyiminoacetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐ones 7 are obtained by reacting with alkyl bromides or iodides in the presence of anhydrous potassium carbonate with moderate yields. The similar compounds can be synthesized on refluxing 3‐acetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐ones 5 with substituted hydroxylamine hydrochloride in the presence of sodium bicarbonate with good yields. Most of the synthesized compounds are characterized by IR and NMR spectroscopic methods.

ChemInform Abstract: Two Expedient “One‐Pot” Methods for Synthesis of β‐Aryl‐β‐mercaptoketones over Anhydrous Potassium Carbonate or Amberlyst‐15 Catalyst.

Two expedient one-pot methods have been developed for synthesis of β-aryl-β-mercaptoketones using acetophenones, benzaldehydes and thiols as starting materials. The methods involve microwave irradi- ation (5 min) of 1:1 mixtures of acetophenones and benzaldehydes over neutral alumina supported anhydrous potassium carbonate or amberlyst-15 in the first step, and that is followed by addition of thiol to the resulting material and keeping at room temperature for 1.5 h.

SYNTHESIS, CHARACTERIZATION AND ANTI-INFLAMMATORY ACTIVITY OF SOME HYDRAZONE DERIVATIVES

A mixture of phenyl acetic acid (10gm, 0.003mole) in acetone, dimethyl Sulphate (10.45ml, 0.007mole), anhydrous potassium carbonate (2.8gm, 0.02mol) was refluxed on a water bath for 2 hr with occasional stirring give methyl 2-phenylacetate(1), Methyl 2-phenylacetate (1.78gm, 0.01mole) in alcohol was refluxed with hydrazine hydrate (0.38gm, 0.01mole) for 8hrs formed 2-phenylacetohydrazide, A mixture of substituted benzaldehyde (1.22gm, 0.01mole) and 2-phenyl acetohydrazide (1.5gm, 0.01mole) were dissolved in methanol then two drops of conc. HCl were added as catalyst and stirred at room temperature for 2hr formed N'-(2-chlorobenzylidene)-2-phenylacetohydrazide,N'-(3,4,5-trimethoxybenzylidene)-2-phenylacetohydrazide, N'-(furan-2-ylmethylene) -2-phenylacetohydrazide, and N'-(3,4,5-trimethoxybenzylidene) -2-phenylacetohydrazide Key-Words: Phenyl acetic acid, Hydrazine-hydrate, NSAID’S, Anti-inflammatory.

Spectral studies of 2-pyrazoline derivatives: Structural elucidation through single crystal XRD and DFT calculations

A series of biologically active N-thiocarbamoyl pyrazoline derivatives have been synthesized using anhydrous potassium carbonate as the catalyst. All the synthesized compounds were characterized by FT-IR, 1H NMR, 13C NMR spectral studies, LCMS, CHN Analysis and X-ray diffraction analysis (compound 7). In order to supplement the XRD parameters, molecular modelling was carried out by Gaussian 03W. From the optimized structure, the energy, dipolemoment and HOMO–LUMO energies of all the systems were calculated.

Novel blue-emitting carboxyl-functionalized poly(arylene ether nitrile)s with excellent thermal and mechanical properties

A series of novel carboxyl-functionalized poly(arylene ether nitrile)s (CPAENs) were synthesized via nucleophilic substitution polycondensation reactions of 2,6-dichlorobenzonitrile with carboxyl-functionalized phenolphthalin and diphenol compounds, using N-methyl-2-pyrrolidone (NMP) as solvent in the presence of anhydrous potassium carbonate. The resulting CPAENs exhibited high glass transition temperatures ranging from 181 °C to 251 °C, and were thermally stable up to 400 °C under either nitrogen or air atmospheres. The incorporation of phenolphthalin-units into the polymer chain imparted an improved solubility of CPAENs in organic solvents, such as NMP, N,N-dimethylformamide, and tetrahydrofuran. The CPAENs were amorphous and can be readily cast into transparent films with a tensile strength of 75.1–104.7 MPa and a tensile modulus of 2.6–3.2 GPa. All CPAENs displayed a highly intense UV absorption in the wavelength range of 280–330 nm and a characteristic blue-emitting fluorescence under the UV irradiation.

Synthesis, Mass Spectra Investigation and Biological Activity of Some Pyrimidine Derivatives

Disubstituted-5-cyano-4-hydroxypyrimidines (3 and 4) have been prepared via cyclocondensation of ethyl-β-(3-bromo-4-methoxy phenyl)-α-cyanoacrylate (2) with guanidine hydrochloride and thiourea in presence of anhydrous potassium carbonate. Treatment of 3 with acetic anhydride, ethyl chloroacetate, methyl acrylate and 4-methylphenacyl bromide afforded the corresponding N-acetyl (6), N-alkyl (9) and fused pyrimidines (7, 8). The electron impact (EI) ionization mass spectral fragmentations of some synthesized compounds are discussed. Some of the synthesized compounds were tested for their antimicrobial and inhibitory activities against Breast carcinoma cells (MCF-7) cell line. I. Introduction Because of their interesting biological activities, low molecular weight heteroycles have attracted enormous attention in medicinal chemistry. Nitrogen-containing heterocycles have recently received a significant importance because of their diverse pharmacological properties (1-5). Of these heterocycles, the synthesis, reactions and biological activities of pyrimidine containing molecules stands as an ever expanding area of research in hetero aromatic chemistry. However, the synthesis of some substituted pyrimidines by the treatment of α,β-unsaturated esters with thiourea and guanidine in the presence of anhydrous potassium carbonate were reported (6). The literature indicated that compounds having pyrimidine nucleus possesses broad range of biological activity like anticancer, antiviral, anti-HIV, antibacterial, antihypertensive, anticonvulsant, antithyroid, and antibiotics (7).The electron Impact (EI) ionization mass spectral fragmentation of some of the synthesized 2-aminopyrimidine and 2-mercaptopyrimidine derivatives were described. II. Results and Discussion 1) Chemistry Condensation of 3-bromo-4-methoxybenzaldehyde (1) with ethylcyanoacetate in the presence of anhydrous potassium carbonate led to the formation of ethyl β-(3-bromo-4-methoxyphenyl)-α-cyanoacrylate (2). The reaction of ester derivative (2) with guanidine hydrochloride and thiourea in methanol in presence of anhydrous potassium carbonate under reflux, yielded the corresponding 6-(3-bromo-4-methoxyphenyl)-5-cyano- 4-hydroxy-2-aminopyrimidine (3) and 6-(3-bromo-4-methoxyphenyl)-5-cyano-4-hydroxy-2- mercaptopyrimidine (4, Scheme 1). Treatment of 2-mercaptopyrimidine (4) with 4-methylphenacyl bromide in presence of fused sodium acetate in acetic acid under reflux afforded the corresponding 6-(3-bromo-4-methoxyphenyl)-5-cyano-4-oxo-3- (p-methylphenyl)-thiazolo(2,3-b)pyrimidine (5; Scheme 1).

Synthesis and properties of poly(aryl ether ketone)s with 2,6-diphenylpyridyl moieties and 4-trifluoromethylphenyl side groups

A new bisphenol monomer, 4-(4-trifluoromethylphenyl)-2,6-bis(4-hydroxyphenyl)pyridine, was prepared and used in the preparation of several aromatic poly(ether ketone)s (PEKs) containing 2,6-diphenylpyridyl moieties and 4-trifluoromethylphenyl side groups via a nucleophilic aromatic substitution polycondensation with four difluorinated aromatic ketones. The polycondensation proceeded quantitatively in tetramethylene sulfone (TMS) in the presence of anhydrous potassium carbonate and afforded the PEKs with number-average molecular weights (Mn's) in the range of 29,800–33,200g/mol and the polydispersity index ranging from 1.93 to 2.06. The resulting PEKs are amorphous, and exhibit glass transition temperatures of 176–203°C, the 5% weight loss temperatures of 545–556°C, and the 10% weight loss temperatures over 563°C in air. These new PEKs are soluble in many solvents such as N-methyl-2-pyrrolidone, N,N′-dimethylacetamide, chloroform and tetrahydrofuran, and could form transparent, strong, and flexible films with tensile strengths of 99.5–113.8MPa, tensile moduli of 3.01–3.75GPa, and elongations at break of 9–14%. Additionally, all the polymers had low dielectric constants of 2.62–2.75 at 1MHz and low water uptake in the range of 0.38–0.46%.