Presence Of Para-toluenesulfonic Acid Research Articles

Synthesis of acetyl deoxyvasicinone analogues from 2-(4-oxopentyl)quinazolin-4(3H)-ones via linear cyclizations

Two deoxyvasicinone analogues were obtained from 2-(4-oxopentyl)quinazolin-4(3H)-ones via different process of linear cyclizations. The first was 1-acetyl-2,3-dihydropyrrolo[2,1-b]quinazolin-9(1H)-one analogue derived from direct cyclization in the presence of I2 in basic condition. The other was 1-acetylpyrrolo[2,1-b]quinazolin-9(3H)-one analogue obtained from two-step procedures beginning with geminal dichlorination in acidic condition, followed by intramolecular CN bond formation in the presence of para-toluenesulfonic acid.

SYNTHESIS AND CHARACTERIZATION OF SOME MODIFIED EPOXY RESINS WITH FATTY ACIDS

Some modified epoxy resins were prepared from the reaction of epoxy resin with some fatty acids (palmitic acid, stearic acid, oleic acid)in the presence of paratoluene Sulfonic acid at low temperature ranging between 70,90C◦ and at high temperature ranging between 280,300C◦. All the epoxy modifiers were characterized by IR and acid value AV. The mechanical properties (Hardness, Impact strength, Elongation, Tensile strength) and thermal stability (TGA) were studied. The mechanical properties of modified are lower than unmodified polymers, but Oleic acid was the best of all. The thermal stability was decreased according to below (Stearic acid> Palmatic acid>Oleic. acid). 

The effect of halo-substituents on physical properties based on 1,3,5-triarylbenzenes: Synthesis, crystal structure and Hirshfeld surface

A set of 1,3,5-triarylbenzenes with the formula of C24H15X3 (X = F (1), Cl (2), Br (3) and I (4)) have been prepared through the cyclotrimerization of the substituted-acetophenones in the presence of para-toluenesulfonic acid (p-TSA). The maximal emission peaks of compounds 1–4 were found at 358, 361, 363 and 374 nm in the solid state, respectively, revealing that the luminescent properties were tuned by the halo-substituent groups. The title compounds were characterized by FT-IR, UV–Vis, elemental analysis (EA) and single-crystal X-ray diffraction. There exist the hydrogen bonds and packing interactions among aromatic rings. Among these compounds, the I-substituent triarylphenyl compound displays the best thermal stabilities. The maximal absorbance peaks, the emission bands, the cell volume, and the decomposition temperature increase with the substituent groups changing from fluorine to iodine. Hirshfeld surface analysis reveals that the order of X···C close contacts are consistent with that of the luminescent maxima.

Synthesis and molecular structures of the 52-electron triiron telluride clusters [Fe3(CO)8(μ3-Te)2(κ2-diphosphine)] - Electrochemical properties and activity as proton reduction catalysts

Heating the 50-electron cluster [Fe3(CO)9 (μ3-Te)2] (1) with the diphosphines Ph2P-R-PPh2 [R = -CH2CH2- (dppe), Z-CH=CH- (dppv), 1,2-C6H4 (dppb), -CH2CH2CH2- (dpp), ferrocenyl (dppf), naphthalenyl (dppbn)] in benzene affords the 52-electron diphosphine-containing tellurium-capped triiron clusters [Fe3(CO)8 (μ3-Te)2 (κ2-diphosphine)] (diphosphine = dppe, dppv, dppb, dpp, dppf, dppnd) (2–7) in moderate yields, resulting from both phosphine addition and carbonyl loss. With 1,2-bis(diphenylphosphino)benzene (dppb) a second product is the cubane cluster [Fe4(CO)10(μ3-Te)4 (κ2-dppb)] (8). Cyclic voltammetry measurements on 2–7 reveal that all clusters show irreversible reductive behaviour at ca. −1.85 V with a series of associated small back oxidation waves, suggesting that reduction leads to significant structural change but that this can be reversed chemically. Oxidation occurs at relatively low potentials and is diphosphine-dependent. The first oxidation appears at ca. +0.35 V for 2–6 with a small degree of reversibility but is as low as +0.14 V for the bis(diphenylphosphino)naphthalene derivative 7 and in some cases is followed by further closely-spaced oxidation. Addition of [Cp2Fe][PF6] to 2–7 results in the formation of new clusters formulated as [Fe3(CO)8(μ3-Te)2(κ2-diphosphine)]+, with their IR spectra suggesting oxidation at the diiron centre. This is supported by computational studies (DFT) of the bis(diphenylphosphino)propane cluster 5 showing that the HOMO is the FeFe σ-bonding orbital, while the LUMO is centered on the diphosphine-substituted iron atom and has significant FeTe σ∗-anti-bonding character consistent with the irreversible nature of the reduction. Complexes 2–7 have been examined as proton reduction catalysts in the presence of para-toluenesulfonic acid (TsOH). All are active at their first reduction potential, with a second catalytic process being observed at slightly higher potentials. While their overall electrocatalytic behaviour is similar to that noted for [Fe2(CO)6{μ-E(CH2)3E}] (E = S, Se, Te), the DFT results suggest that as the added electron is localised on the unique iron atom. The mechanistic aspects of hydrogen formation are likely to be quite different from the more widely studied diiron models.

Anticancer activity of synthetic bis(indolyl)methane-ortho-biaryls against human cervical cancer (HeLa) cells

Bis(indolyl)methane appended biaryls were designed, synthesized and evaluated in human cervical cancer cell lines (HeLa) for their anticancer activities and compared against normal rat cardiac myoblasts (H9C2) cells. Compounds 1–12 were synthesized, with variations in one of the phenyl unit, in a single step by condensation of biaryl-2-carbaldehydes with indole in the presence of para-toluenesulfonic acid. Compound 1 exhibited a GI50 value of 11.00 ± 0.707 μM and the derivatives, compounds 4 and 11 showed a GI50 value of 8.33 ± 0.416 μM and 9.13 ± 0.177 μM respectively in HeLa cells and was found to be non-toxic to H9C2 cells up to 20 μM. Furthermore, compounds 1, 4 and 11 induced caspase dependent cellular apoptosis in a concentration-dependent manner, reduced mitochondrial membrane potential, inhibited the cell migration and downregulated the production of MMP-2 and MMP-9 in HeLa cells.

Synthesis of new derivatives of pyrazol-chromeno[2,3-d]pyrimidine-ones by a one-pot three-component reaction

A new three-component reaction between salicylaldehydes, barbituric acid, pyrazolones, in the presence of para-toluenesulfonic acid, efficiently provides pyrazol-chromeno[2,3-d]pyrimidine-ones derivatives in good yields in ethanol/water at 70 °C. This multicomponent reaction showed high atom economy.

Kinetics and Mechanisms of Homogeneous Catalytic Reactions. Part 12. Hydroalcoxycarbonylation of 1-Hexene Using Palladium/Triphenylphosphine Systems as Catalyst Precursors

Systems prepared in situ by addition of n equivalents of triphenylphosphine to palladium dichloride in the presence of m equivalents of para-toluenesulfonic acid (TSA), PdCl2/nPPh3/mTSA (n and m varying between 2 and 10), were used as precatalysts for the olefin carbonylation (1-hexene, cyclohexene and styrene) with alcohols (MeOH, EtOH, n-PrOH and i-PrOH) to generate the corresponding esters (hydroalcoxycarbonylation), under mild reaction conditions. For 1-hexene carbonylation in presence of methanol (1-hexene hydromethoxycarbonylation), the most active system was PdCl2/6PPh3/5TSA at P(CO) = 50 atm and T = 125 °C, which was also active for the hydromethoxycarbonylation of other olefins (1-hexene > styrene > cyclohexene). This system was regioselective towards the linear product for 1-hexene and towards the branched product for styrene. A kinetic study of 1-hexene hydromethoxycarbonylation catalyzed by PdCl2/6PPh3/5TSA showed that the initial reaction rate (r o) was first order on Pd and MeOH concentrations and fractional order with respect to CO concentration; for olefin concentration was found a saturation curve. These kinetic results, together with coordination chemistry and computational DFT studies, allow us to propose a catalytic cycle involving species of the type [Pd(H)(L)(PPh3)2]+n (L = Cl, n = 0; L = CO, MeOH, olefin and PPh3, n = 1) as the catalytically active species and three sequential reactions: (1) olefin insertion into the Pd–H bond to yield Pd–alkyl species, (2) CO insertion into the Pd–C bond to generate Pd–acyl intermediates, and (3) the methanolysis of Pd–acyl species to produce the corresponding methyl esters, regenerate the active species and restart the cycle; the last reaction is considered the rate-determining step (rds) of the mechanism. Systems prepared in situ by addition of triphenylphosphine to palladium dichloride in the presence of para-toluenesulfonic acid (TSA), PdCl2/nPPh3/mTSA were used as precatalysts for the olefin carbonylation with alcohols (MeOH, EtOH, n-PrOH and i-PrOH) to generate the corresponding esters (hydroalcoxycarbonylation), under mild reaction conditions. For 1-hexene hydromethoxycarbonylation, the most active system was PdCl2/6PPh3/5TSA at P(CO) = 50 atm and T = 125 oC. Kinetic, coordination chemistry and computational DFT studies, allow us to propose a catalytic cycle involving species of the type [Pd(H)(L)(PPh3)2]+n (L = Cl, n = 0; L = CO, MeOH, olefin, n = 1) or [Pd(H)(PPh3)3]+ as the catalytically active species.

Convenient and Scalable Process for the Preparation of Bupropion Hydrochloride via Efficient Bromination of m-Chloropropiophenone with N-Bromosuccinimide

A convenient, scalable, and commercially viable process for the production of the antidepressant drug bupropion hydrochloride (1) is reported. The process relies upon an improved, large-scale synthesis of the key intermediate, m-chloro-α-bromopropiophenone (4). During process development, bromine was replaced with N-bromosuccinimide (NBS) in the presence of para-toluene sulfonic acid (p-TSA), for the bromination of m-chloropropiophenone (3), in either a very low volume of acetonitrile or under solvent-free conditions, to furnish 4. Intermediate 4 was further reacted with t-butylamine in N-methyl-2-pyrrolidinone (NMP) to afford bupropion free base (5), followed by treatment with a saturated solution of hydrochloric acid in isopropyl alcohol (IPA-HCl) to afford bupropion hydrochloride (1). This improved process provides pure bupropion hydrochloride (1) in good yields and at considerably lower cost than existing processes, and it does not involve the use of hazardous reagents.

Efficient Thiocyanation of Indoles Using Para-Toluene Sulfonic Acid

Treatment of indoles with ammonium thiocyanate in the presence of para-toluene sulfonic acid afforded the corresponding 3-thiocyano indoles at room temperature in excellent yields.

Influence of dopant in the synthesis, characteristics and ammonia sensing behavior of processable polyaniline

Polyaniline (PANI) was synthesized by oxidative polymerization of aniline as well as aniline hydrochloride by ammonium persulfate in the presence of para-toluene sulfonic acid (PTSA). This helped in direct usage of the conducting PANI solution for film casting and use as a device for ammonia gas sensing. Viscosity change with applied shear rate was measured for both the polymers. Solid PANI powder was isolated from its tetrahydrofuran solution by using methanol as non-solvent. Thermogravimetric analysis investigated the thermal properties of the solid PANI salts. Elemental analysis of both PANI synthesized in presence of PTSA and PANI synthesized in presence of HCl and PTSA was investigated. A thin coherent film of both the conducting PANI were deposited on glass slides precoated with poly vinyl alcohol (PVA) crosslinked with maleic acid (MA) and was directly used in the sensor device. The morphology of the deposited films was analyzed by scanning electron micrograph. The films were further characterized by Attenuated total reflectance Fourier transformed infrared spectroscopy, ultra violet-visible spectroscopy and X-ray diffraction analyses. Finally, both the doped PANI films on MA crosslinked PVA coated glass slides were used to measure the conductivity and ammonia gas-sensing characteristics.

New method for post-processing crosslinking reaction

A new processing method to process functionalized polymer materials that are able to crosslink has been developed. The crosslinking reaction occurs after the melt processing stage at moderate temperature and without the addition of external reagents. Maleic anhydride-ethylene copolymer was processed with 1,4-butanediol in the presence of para-toluene sulfonic acid as catalyst. To prevent the reaction in the melt, it was chosen to trap the 1,4-butanediol onto vector particles. The extent of the crosslinking reaction during the mixing at 110 °C has been studied for three different particles taken as vector particles. It was found that Orgasol ® polyamide particles are efficient to inhibit the crosslinking reaction in the mixer. The reaction then takes place at 40 °C and after 100 h the cured samples appeared to be highly and homogeneously crosslinked with a gel content above 90%.

Synthesis of oil based hyperbranched resins and their modification with melamine-formaldehyde resin

In this research hyperbranched resins containing fatty acid residues were synthesized. Dipentaerythritol which has six hydroxyl groups was used as the core molecule, and it was transesterified with (i) castor oil, and (ii) a mixture of castor oil and linseed oil at 240 °C. The resulting molecule had hydroxyl containing ricinoleic acid residue coming from castor oil. It was then esterified with dimethylol propionic acid at 140 °C in the presence of para-toluene sulfonic acid used as catalyst. The hyperbranched resin thus produced was then mixed with melamine-formaldehyde resin to improve its properties. The resins were characterized by FTIR spectroscopy, and the thermal properties were determined by DSC. The resins were thermally stable up to 316 °C. The viscosity of the resin that was synthesized by using only castor oil was 3.0 Pa s, while the one synthesized by using 50% linseed oil had a viscosity of 1.0 Pa s. When reacted with dimethylol propionic acid the viscosity of the former resin increased to 7.0 Pa s, and that of the second to 3.7 Pa s. The hyperbranched resins showed excellent adhesion, gloss, flexibility, and formability. The mixed resin (i.e. hyperbranched and melamine-formaldehyde) had higher hardness values but lower gloss, adhesion, and bending resistance. Both types of resins also had good impact and abrasion resistances.

Ionic liquids as catalytic “green” reactants and solvents for nucleophilic conversion of fatty alcohols to alkyl halides

We show that ionic liquids such as 1-octyl-3-methylimidazolium bromide or iodide (OMIM/X) make excellent reagents and solvents for the transformation of fatty alcohols into fatty halides in the presence of paratoluene sulfonic acid (PTSA). The conversion used either direct or microwave heating with excellent yields. The ionic liquid was successfully regenerated and reused.

Borderline mechanisms involving ion-molecule pairs for the nucleophilic substitution reactions of benzhydrol and its derivatives. Facile formation and cleavage of diphenylmethyl ethers for the protection of hydroxyl groups

Nucleophilic substitution reactions of benzhydrol and its derivatives, in refluxing benzene in the presence of para-toluenesulfonic acid, took different routes depending on whether para-toluenesulfonic acid was used in excess or in catalytic amounts. In the first case the reactions took place via benzhydryl carbocations and in the second case they proceeded via intimate ion-molecule pairs. On the basis of this study, facile methods for introduction and removal of CHPh2 as a protective group of alcohols are presented.

Synthesis of functionally substituted 2-cyanoacrylates

The conditions for the Knoevenagel synthesis of 2-cyanoacrylates containing double and triple bonds in the alkoxycarbonyl group have been studied. It was found that the esters are formed in 10–70 % yields by the condensation of the respective cyanoacetates with formaldehyde in the 1∶1 ratio in the presence of piperidine, followed by the pyrolysis of the oligomers formedin vacuo at 170–200 °C in the presence ofpara-toluenesulfonic acid. The compounds synthesized readily undergo polymerization at room temperature and can be used as the basis for thermostable rapidly polymerizing adhesives.

L'epoxy-pyronène : Synthon d'accès aux cyclocitrals et aux ionones et précurseur de nouveaux composés terpénoïdes

The selective obtention of epoxy-pyronene from δ-pyronene has been realized using metachloroperbenzoïc acid. The isomerization of this epoxydic compound with Lewis and protonic acids and on active alumina has been studied leading to cyclocitrals. Ionones are obtained from epoxy-pyronene by homologation with various C 3 units, in the presence of paratoluenesulfonic acid in order to obtain β-cyclocitral in situ. New terpenic compounds with the cyclogeranyl skeleton were obtained from epoxy-pyronene by reduction followed by homologation.

The role of complexing ligands in the formation of non-aggregated nanoparticles of zirconia

The hydrolysis and condensation of zirconium n-propoxide in n-propanol have been chemically controlled via the complexation of the zirconium precursor with acetylacetone. The size of the zirconium oxide-based particles is mainly controlled by the complexation ratio x=[acac]/[Zr]. the mean size increases from nanometric to submicronic range when x decreases from 1 to 0.1. Amorphous colloidal particles are obtained at room temperature. They result from a competitive growth/termination mechanism of zirconium-oxo species in the presence of acac surface capping agents. However non-aggregated nanocrystalline particles of tetragonal zirconia, about 2 nm in diameter are formed upon aging at 60°C when hydrolysis is performed in the presence of paratoluene sulfonic acid (PTSA).

ChemInform Abstract: THE CHEMISTRY OF SOME 6‐METHYL‐4‐HYDROXY‐2‐PYRIDONES

AbstractOxidation von (I) mit NaIO4 liefert den Aldehyd (II), Behandlung von (Ia) mit Ethylenglykol in Gegenwart von TosOH führt zum Ether (III).