Effect of Cation Structure in Quinolinium-Based Ionic Liquids on the Solubility in Aromatic Sulfur Compounds or Heptane: Thermodynamic Study on Phase Diagrams

Experimental and theoretical studies on thermodynamic properties of quinolinium-based ionic liquids (ILs) based on bis(trifluoromethylsulfonyl)imide anion (namely N-butyl-quinoloinium bis(trifluoromethylsulfonyl)imide, [BQuin][NTf₂], N-hexylquinoloinium bis(trifluoromethyl-sulfonyl)imide, [HQuin][NTf₂], and N-octylquinoloinium bis(trifluoromethyl-sulfonyl)imide, [OQuin][NTf₂]) with aromatic sulfur compounds and heptane, as a model compound of fuel were examined in order to assess the applicability of the studied ionic liquids for desulfurization of fuels. With this aim, the temperature-composition phase diagrams of 13 binary mixtures composed of organic sulfur compounds (thiophene, benzothiophene, or 2-methylthiophene) or heptane and ionic liquid (IL) were investigated at ambient pressure. A dynamic method was used to determine the (solid–liquid) equilibrium phase diagrams in binary systems over a wide composition range and temperature range from T = 255.15 to 365.15 K up to the fusion temperature of ILs. The immiscibility gap with an upper critical solution temperature (UCST) was observed for each binary system under study. The influence of the alkane chain length of the substituent on the IL cation and of the sulfur compounds (the aromaticity of the solvent) was described. The experimental (solid + liquid) phase equilibrium dataset were successfully correlated using the well-known NRTL equation.     

[1,3]-Dipolar cycloaddition of N-aryl sydnones to benzothiophene 1,1-dioxide, 1-cyclopropylprop-2-yn-1-ol and 1-(prop-2-ynyl)-1H-indole

[1,3]-Dipolar cycloadditions of N-aryl sydnones to benzothiophene 1,1-dioxide, 1-cyclopropylprop-2-yn-1-ol and 1-(prop-2-ynyl)indole gave fused pyrazole derivatives when carried out in refluxing toluene. While the first two dipolarophiles gave single regioisomers, this indolic derivative gave mixtures, the ratios of which appeared to be controlled by the phenyl substituents. Their structures were identified in the usual manner, supported by single crystal X-ray diffraction measurements.     

Liquid-phase oxidation of benzothiophene and dibenzothiophene by cumyl hydroperoxide in the presence of catalysts based on supported metal oxides

The liquid-phase oxidation of benzothiophene and dibenzothiophene by cumyl hydroperoxide in the presence of supported metal oxide catalysts was carried out in octane in an N₂ atmosphere at 50–80°C. The cumyl hydroperoxide, benzothiophene, and dibenzothiophene conversions and the yield of sulfones were determined for catalysts of various natures. In the presence of MoO₃/SiO₂, the most efficient and most readily regenerable catalyst, the benzothiophene conversion was ～60% and the dibenzothiophene conversion was as high as 100% upon almost complete consumption of cumyl hydroperoxide. The influence of unsaturated and aromatic compounds (oct-1-ene, toluene) on the catalytic effect was studied. The kinetics of substrate oxidation and cumyl hydroperoxide decomposition and an analysis of the cumyl hydroperoxide conversion products suggested a benzothiophene and dibenzothiophene oxidation mechanism including the formation of an intermediate complex of the hydroperoxide with the catalyst and the substrate and its transformation via heterolytic and homolytic routes.     

Chloration et S-oxydation du benzo[b]thiophène par l'hypochlorite de tertiobutyle. Mécanisme de la réaction

In the reaction with benzothiophene, t-butyl hypochlorite acts simultaneously as a smooth oxidizing agent and as a chlorinating agent since it is a source of both hypochlorous acid and chlorine. The mixture of all the products obtained imply that the reaction intermediate is the unstable benzothiophene I-oxide which was shown to be present by the stop flow technique. The chlorine formed traps the highly reactive benzothiophene 1-oxide in situ to give the observed products.     

Facile synthesis of [1]benzothieno[3,2-b]benzothiophene from o-dihalostilbenes

A convenient one-pot synthesis of [1]benzothieno[3,2-b]benzothiophene from readily available o-dihalostilbenes using combined reagents of sodium sulfide nonahydrate (Na₂S·9H₂O) or sodium hydrosulfide hydrate (NaSH·nH₂O) and sulfur is described along with plausible reaction paths in this intriguing reaction.     

Activite optique de polyamines tertiaires du type poly[thio-(N-R1-N-R2 aminomethyl)-1 ethylene]

Ultra-violet, ORD and CD spectra of (?)poly[thio1-(N-N-diethylaminomethyl) ethylene] (Ia) prepared by stereoelective polymerization of racemic N-N-diethyl-N-(thiirane-2-ylmethyl) amine using ZnEt₂-(—) 3-3-dimethyl-1,2 butanediol as initiator system, of (+)poly[thio1-(N-N-diethyl aminomethyl) ethylene] obtained from a partially resolved enantiomer using ZnEt₂-CH₃OH as initiator system, of poly[thio1-(N-methyl-N-sec-butyl aminomethyl) ethylene] and of poly[thio1-(N-methyl-N-(1-phenylethyl) aminomethyl) ethylene] in organic solvents (tertiary amine form) and in water (hydrochloride form) are described. Observed Cotton effects are associated with electronic transitions of chromophores by comparison with model molecules: N-methyl2-aminobutane, ethyl-thio-2-methylbutane and polypropylene sulfide. For polyamine (Ia), their contributions to optical rotatory powers in the visible are evaluated after decomposition of corresponding CD curves in Gaussian partial Cotton effects. The effects of other optically active electronic transitions located below 180 nm are deduced by difference. Influence of positions of chromophores with regard to chiral centers and of the protonation of nitrogen atoms on observed Cotton effects are discussed.     

Hydroboration d'amines insaturees: XI. Regio- et stereoselectivite des hydrures du bore vis a vis d'amines propargyliques N-phosphorylees

The regioselectivity and the stereoselectivity of the hydroboration of N-alkylallylphosphoramide was examined. This study shows the preferential formation of γ-boron derivatives (90 to 100%) and the excellent stereospecificity of the reaction (100% (Z) configuration).The P^IV-N bond hinders the nitrogen-boron coordination which is responsible for the anomalous behavior of N-propargylic amines towards hydroboration and allows the same regio- and stereo-selectivity as for alkynes. The iodination of boron derivatives leads, with good yields, to N-phosphoryl-β-ethylenic amines.     

Dosage du plutonium par potentiometrie a intensite constante: Application au combustible de rapsodie

A new method is proposed for the determination of plutonium in the UO₂PuO₂ pellets for Rapsodie. The sample is dissolved in a mixture of II N nitric acid and 0.l N hydrofluoric acid, and the plutonium is oxidized with silver(II) oxide. Plutonium(VI) is reduced in the presence of sulphamic acid with an excess of iron(II) which is back-titrated with cerium(IV) solution to a constant-current potentiometric end-point. Uranium and iron do not interfere and no separation is required. In routine work, the method gives a precision of 0.5%.     

Ions α-cetocarbenium : Mode de formation,influence de l'orientation du groupe partant et du milieu

AgSbF₆/CH₂Cl₂ dehalogenation of endo and exo 3-bromocamphor, and protonation in different conditions of α-diazocamphor, lead to products determined by the leaving group orientation. This shows that these two reactions do not lead to the corresponding α-ketocarbenium ion, but that the departure of Br^? or N₂ is anchimerically assisted. The fact that the protonation of α-diazocamphor, by a superacid (HSbF₆), leads specifically to the same product as that from AgSbF₆ dehalogenation, in the same solvent, of endo 3-bromocamphor, shows that these two reactions involve a common intermediate, contradictory with the “hot carbonium ion” concept. This result also shows that α-diazocamphor is kinetically protonated at the exo face.     

Synthesis of Benzo[b]thiophene Carboxamides Connected to 4‐Arylpiperazines through a Benzylic Spacer: Potential Ligands with 5‐HT1A Binding Affinity

New benzothiophene arylpiperazine derivatives 8 (a–f) were synthesized as potential serotoninergic agents with 5‐HT_1A receptor affinity. Preparation of the derivatives was performed by treating N‐[2‐(chloromethyl)phenyl]‐4,7‐dimethoxybenzo[b]thiophene‐2‐carboxamide (7) with a series of substituted 4‐arylpiperazines.     

Réactivité de l'hypochlorite de tertiobutyle dans l'oxydation du benzothiophene

In reaction with benzothiophene, t-butyl hypochlorite acts as an oxidizing reagent and a chlorination reagent. A mixture of 3-ehlorobenzothiophene, three 2,3-dichloro-2,3-dihydrobenzothio-phene 1-oxide isomers (trans-anti: trans-syn; cis-anti) and 2-chlorobenzothiophene 1-oxide was obtained. With a large exces of t-butyl hypochlorite, the reaction leads to 2,3-dichlorobenzothio-phene, 2,3-dichlorobenzothiophene 1-oxide. 2,2,3-trichloro-2,3-(lihydrobenzothiophene 1-oxide and 2,3-dichloro-3-oxobenzothio-phene 1-oxide. In any case, oxidation stops at the level of the sulfoxide.     

The nature of interactions between N-butylpyridinium tetrafluoroborate and thiophenic compounds: A theoretical investigation

In an effort to understand the nature of the interactions between pyridinium-based ionic liquids and thiophenic compounds, the electronic and topological properties of the interactions between N-butylpyridinium tetrafluoroborate ([BPY]⁺[BF₄]⁻) and thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT) have been investigated by density functional theory. The most stable structure of the [BPY]⁺[BF₄]⁻ ion-pair indicated that hydrogen bonding interactions between fluorine atoms on [BF₄]⁻ anions and C2–H2 on the pyridinium ring play an important role in the formation of the ion-pair. The NBO and AIM analyses indicate the occurrence of π–π stacking interactions. The electron density at bond critical points and Wiberg bond indices are correlated with the interacting distances of H···F interactions, so electron density and Wiberg bond index can demonstrate the interacting strength of H···F hydrogen bonds. The interaction energies suggest that DBT adsorbs prior to the other compounds on N-butylpyridinium tetrafluoroborate ionic liquid.     

Synthese des substances de groupe sanguin—IX: Une synthese du 2-o-(α-l-fucopyranosyl)-3-o-(α-d-galactopyranosyl)-d-galactose,le determinant antigenique du groupe sanguin b

The trisaccharide 2-O-(α-L-fucopyranosyl)-3-O-(α-D-galactopyranosyl)-D-galactose has been synthesised stereospecifically using the imidate procedure. Allyl 3-O-benzoyl-4,6-O-benzylidene-β-D-galactopyranoside was first α-L-fucosylated by 1-O-(N-methyl)-acetimidyl-2,3,4-tri-O-benzyl-β-L-fucopyranose then, after O-debenzoylation, α-D-galactosylated by 1-O-(N-methyl)-acetimidyl 2,3,4,6-tetra-O-benzyl-β-D-galactopyranose. The resulting tri-saccharide has also been obtained from allyl 2-O-benzoyl-4,6-O-benzylidene-β-D-galactopyranoside after α-D-galactosylation, O-debenzoylation and α-L-fucosylation. The glycosylations were performed at room temperature in nitromethane in the presence of p-toluenesulfonic acid. Deallylation followed by catalytic hydrogenolysis gave the B blood-group antigenic determinant. The allyl group was also selectively transformed into hydroxyethyl group.     

Synthesis of benzothiophene analogues of ketoconazole and itraconazole

The synthesis of the benzothiophene analogues of the orally active antifungal agents ketoconazole and itraconazole 3a and 3b is reported. The key heterocyclic system 3-(1-piperazinyl)benzo[b]thiophene is prepared by formation of the enamine between a benzothienone and ethyl 1-piperazinecarboxylate. After elaboration of the respective N-substituents, the methoxy group is cleaved with boron tribromide, and O-alky-1ated with the corresponding mesylates.     

Über die Si3-N-bindung: XXXV. Darstellung von N-β-halogenäthyl-N,N-bis(trimethylsilyl)aminen

N-β-Haloethyl-N,N-bis(trimethylsilyl)amines, which can be used for the introduction of aminoethyl groups into organic or organosilicon compounds, are prepared in good yields from N-trimethylsilylaziridine and trimethylhalosilanes. This reaction is spontaneous with trimethylbromo- and -iodosilane, whereas it is necessary to run the reactions with trimethylchlorosilane in the presence of dipolar aprotic solvents and at higher temperatures.N-β-Bromoethyl-N,N-bis(trimethylsilyl)amine (II) is also obtained by silylation of N-β-bromoethylamine hydrobromide with trimethylsilyldiethylamine or with N-trimethylsilyl-N-methyl acetamide. Furthermore N-β-iodoethyl-N,N- bis(trimethylsilyl)amine is prepared by the reaction of II with MgI₂ or of aziridine and N-trimethylsilylaziridine respectively, with trimethylchlorosilane and MgI₂.From the silylation of N-β-bromoethylamine hydrobromide with trimethylsilyldiethylamine N,N-bis(trimethylsilyl)-N′,N′-diethylethylenediamine is isolated as a side product or, at higher temperatures, as the main product.     

Synthesis of bischromones by deformylative Mannich type reaction on chromone-3-carbaldehyde using α-aminoacid as the source of amine

Chromone-3-carbaldehyde reacts with N-methylglycine or glycine in the presence of excess formaldehyde to produce N-(chromone-3-ylmethyl)-N-methylglycine or N,N-di(chromone-3-ylmethyl)glycine, respectively, by a deformylative Mannich type reaction. Use of alanine or leucine or methionine in place of glycine produces N-(chromone-3-ylmethyl)alanine/-leucine/-methionine, respectively.     

Antibacterial activity of N-quaternary chitosan derivatives: Synthesis, characterization and structure activity relationship (SAR) investigations

Quaternary N-(2-(N,N,N-tri-alkyl ammoniumyl and 2-pyridiniumyl) acetyl) derivatives of chitosan polymer, chitooligomer, and glucosamine (monomer) were synthesized for the purpose of investigating the structure activity relationship (SAR) for the antibacterial effect. Novel methods were used in the synthesis. The final chitosan and chitooligomer derivatives could thus be obtained in two steps without prior protection of the hydroxyl groups. However, in order to obtain chitosan derivatives with the bulky N,N-dimethyl-N-dodecyl- and N,N-dimethyl-N-butyl side chains three steps were needed, starting from 3,6-O-di-tert-butyldimethylsilyl chitosan (3,6-O-di-TBDMS chitosan) as the key intermediate. The quaternary ammoniumyl acetyl derivatives of glucosamine were synthesized from glucosamine or tetra-O-acetylglucosamine. N,N,N-trimethyl chitosan (TMC) was used as reference compound for investigation of antibacterial activity. Clinical Laboratory Standard Institute (CLSI) protocols were used to determine MIC and MLC for activity against clinically important Gram-positive strains Staphylococcus aureus (ATCC 25923), and S. aureus (MRSA) (ATCC 43300), and Gram-negative strains of Escherichia coli (ATCC 25922), P. aeriginosa (ATCC 27853) and Enterococcus facialis (ATCC 29212). The MIC values for the compounds ranged from 8 to ?8192 mg/L. In general the N-(2-(N,N-dimethyl-N-dodecyl ammoniumyl) acetyl) derivatives of chitooligomer and glucosamine monomer were more active against bacteria than derivatives with shorter alkyl chains. In contrast the N-(2-(N,N-dimethyl-N-dodecyl ammoniumyl) acetyl) derivatives of chitosan were less active than derivatives with N-(2-N,N,N-trimetylammoniumyl) acetyl or N-(2-(N-pyridiniumyl) acetyl) quaternary moiety. N,N,N-trimethyl chitosan (TMC) was the most active compound in this study.     

One-step synthesis of [1]benzothieno[3,2-b][1]benzothiophene from o-chlorobenzaldehyde

Simple one-step synthesis of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) from commercially available o-chlorobenzaldehyde is reported. The procedure is also applicable to the synthesis of dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT).     

Palladium-catalyzed benzylic-like nucleophilic substitution of benzofuran-, benzothiophene- and indole-based substrates by dimethyl malonate anion

The palladium-catalyzed benzylic-like nucleophilic substitution of acetates derived from benzofuran, benzothiophene and indole was investigated. The asymmetric substitution on racemic 1-(2-benzofuryl)ethyl acetate gave disappointing results, but the substitution product was obtained in 98% ee from (S)-1-(2-benzofuryl)ethyl acetate with overall retention of configuration.     

Highly efficient mesoporous WO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>/KIT-6 catalysts for oxidative desulfurization of dibenzothiophene with hydrogen peroxide

Oxidative desulfurization (ODS) of organic compounds containing sulfur element from a model oil was performed using tungsten oxide catalysts supported on mesoporous silica with cubic Ia3d mesostructure, well-defined mesopores (7.2 nm), high surface area (719 m²/g), and three-dimensional pore network (WO _x /KIT-6). The prepared WO _x /KIT-6 catalysts (5–20 wt% WO _x ) were characterized by X-ray diffraction analysis, N₂ sorption measurements, electron microscopy, H₂-temperature programmed reduction, Raman spectroscopy, and thermogravimetric analysis. Among the mesoporous catalysts, 10 wt% WO _x /KIT-6 exhibited the best catalytic performance. Sulfur-containing organic compounds, such as dibenzothiophene, 4,6-dimethyldibenzothiophene, and benzothiophene, were completely (100 %) removed from the model oil over 10 wt% WO _x /KIT-6 catalyst in 2 h. In addition, the catalyst could be reused several times with only slight decrease in catalytic activity.