Preparative investigations of bromoantimonates(III)

In aqueous hydrobromic acid the reaction between antimony tribromide and amine hydrobromides gives rise to only one type of bromoantimonate(III), irrespective of the initial ratio of the reactants. Different types of bromoantimonates containing the same protonated amine cation have been prepared by the interaction of antimony tribromide with the amine hydrobromide, in appropriate ratios, at higher temperatures in the absence of solvent and also by a metathetical reaction between an amine hydrobromide and bromoantimonate of another amine in acetone. Conductimetric titrations of antimony tribromide with amine hydrobromides in isopropanol were used to establish the stoichiometry of these reactions.     

Synthesis and Application of Poly(diallyldimethylammonium tribromide)as a Novel Polymeric Brominating Agent

In this study, the synthesis and applications of a new supported tribromide reagent based on poly(diallyldimethylammonium chloride) is reported. This supported tribromide is used in α‐bromoacetalization of ketones, bromination of alkenes and regioselective bromination of activated aromatic compounds. This method is mild and no Br₂ and HBr were used. Other advantages of this reagent are stability, high efficiency, simple filtera‐ bility and reusability.     

Two novel halogeno(cyano)argentates with efficient luminescence

The reactions of silver(I) cyanide with tetraalkylammonium salts in anhydrous tetrahydrofuran (THF) under solvothermal conditions and then diffused with ether lead to two novel mixed halogeno(cyano)argentates(I) with efficient luminescence.     

Indium (III) Tribromide : An Excellent Catalyst for Biginelli Reaction

A highly efficient catalyst indium (III) tribromide is used to synthesize 5-alkoxy- carbonyl-4-hydrocarbyl-3,4-dihydropyrimidin-2(1H)-ones by a three-component coupling of β-keto ester, aldehydes and urea through improved Biginelli reaction.     

Efficient synthesis of bis(indolyl)methanes catalyzed by(PhCH2PPh3)+Br3-under solvent-free conditions

<正>Benzyltriphenylphosphonium tribromide(BTPTB) has been applied as an efficient catalyst for the preparation of bis(indolyl)-methanes (BIMs) via electrophilic substitution of indoles with aldehydes in the absence of solvent.     

Mixed tetrahaloantimonates(III)

Monofluorotrichloro- and monofluorotribromoantimonates(III) have been isolated from non-aqueous medium by the interaction of antimony trichloride/tribromide and amine hydrofluoride in appropriate stoichiometric ratios. Conductimetric titrations of antimony trichloride with amine hydrofluoride were carried out in order to establish the stoichiometry of the reaction between them. These complexes have been characterized by chemical analysis. melting points, molar conductance measurements, IR spectral study and thermogravimetric analysis.     

Stereoselective Synthesis of Some Dialkyl (E)-2-Bromomethylene Glutarates

Reaction of 2-bromo-2-bromomethyl glutaric acid esters with tetraalkylammonium fluoride in HMPA, conveniently provides the corresponding dialkyl (E)-2-bromomethylene derivatives in good yields.     

Synthesis of bis(3,3-dinitrobutyl)polysiloxanes

Phenyl groups were used as silicon-protecting groups in the synthesis of bis-(3,3-dinitrobutyl)polysiloxanes. The addition of diphenylsilane to acrolein dimethyl acetal, followed by reactions with methyllithium and phosphorus tribromide gave bis(3-bromobutyl)diphenylsilane. Sodium nitrite displacement gave bis(3-nitrobutyl)diphenylsilane, and oxidative nitration gave bis(3,3-dinitrobutyl)diphenylsilane. Dephenylation with bromine and hydrolysis gave cyclic polysiloxanes.     

Tetrabutylammonium tribromide as efficient catalyst in the synthesis of bis(indolyl)methanes

An efficient procedure has been developed for the synthesis of bis(indolyl)methane derivatives by condensation of aldehydes with indole in the presence of tetrabutylammonium tribromide as catalyst.     

On bromination of 2,4-pentanedionato-copper(II)

Treatment of bis-2,4-pentanedionato-copper(II), with liquid bromine, at room temperature, gave a low melting dark green reaction product containing weakly coordinated tribromide ion. Characterization of this product using elemental analysis, conductivity, electronic, IR and ESR-spectra was carried out and suggested that the composition of the product was [Cu(HacacBr)Br(Br₃)].     

Hantzsch reaction of 3-(2-bromoacetyl)tropolone. Synthesis of 3-(4-thiazolyl)tropolones

3-Acetyltropolone was brominated with phenyltrimethylammonium tribromide to afford 3-(2-bromoacetyl)-tropolone ( 2 ), whose reactions with thiourea, thioformamide, and ammonium dithiocarbamate gave respectively 3-(2-amino-4-thiazolyl)-, 3-(4-thiazolyl)-, and 3-(2-mercapto-4-thiazolyl)tropolone. In a similar manner, compound 2 was treated with six 1-substituted 2-thioureas and three thioamides to give the corresponding 3-(4-thiazolyl)tropolone derivatives.     

Effect of the nature of the counterion on the interaction between cesium and tetraalkylammonium dodecylsulfates and poly(ethylene oxide) or poly(vinylpyrolidone)

The interaction between poly(ethylene oxide) or poly(vinylpyrrolidone) and cesium and tetraalkylammonium (tetramethyl to tetrabutyl ammonium) dodecylsulfate has been investigated by means of electrical conductivity measurements to determine the critical aggregation concentration (cac) of the surfactants in the presence of polymer. The cac values were compared to the values of the critical micellization concentration (cmc) of the surfactants in the absence of polymer. The value of the cac/cmc ratio increased with the radius of the counterion in the sequence: Na(+)相似文献   

Electrochemical Reduction of Vanadium(V)‐Cupferron Complex,VO(cupf)2OH

Electrochemical reduction of vanadium(V) complex with cupferron (N‐nitroso‐N‐phenylhydroxylamine), V^VO(cupf)₂OH, has been studied by polarography in wide potential range to verify the catalytic mechanism of electroreduction of coordinated cupferron ligand. Reduction of the complex was studied in the concentration range from 2 ? 10^?5 M to 10^?3 M. Depending on the process conditions kinetics of catalytic reduction of coordinated cupferron is either controlled by adsorption step or governed by mixed control of diffusion and chemical reaction. Kinetic parameters of the reduction process are reported. Reduction of V^VO(cupf)₂OH complex is accompanied by adsorption and autoinhibition phenomena. V(II) ion in the surface bound complex of vanadium with cupferron catalyzes reduction of coordinated cupferronate ligands. In 1 mM solutions, the catalytic reduction of coordinated cupferron ligand shifts to more cathodic potentials due to formation of a monolayer of adsorbed vanadium(III)‐cupferron complexes. Reduction kinetics in the presence of tetraalkylammonium salt is consistent with multilayer cooperative adsorption of anionic vanadium(II)‐cupferron complex and tetraalkylammonium cations.     

A Convenient Route to 2-(Hydroxy)-3,6,7,10,11-pentaalkyloxytriphenylenes

Unsymmetrical monohydroxypentaalkoxytriphenylenes have been conveniently prepared from the readily accessible symmetrical hexa-alkyloxytriphenylenes using boron tribromide mediated ether cleavage.     

A Facile Synthesis of 5-N,N-Bis(2-Hydroxyethyl)Amino-2-Thiophenecarboxaldehyde

Amination of 5-bromo-2-thiophenecarboxaldehyde with an acyclic secondary amine - bis(2-methoxyethyl)amine was effected by using weak base sodium bicarbonate. The resulting 5-N,N-bis(2-methoxyethyl)amino-2-thiophenecarboxaldehyde was treated with boron tribromide to give 5-N,N-bis(2-hydroxyethyl)amino-2-thiophenecarbox- aldehyde.     

Preparation of tri- and difluoromethylated amines from aldimines using (trifluoromethyl)trimethylsilane

[reaction: see text] Addition of a trifluoromethyl group into aldimines was accomplished using (trifluoromethyl)trimethylsilane with tetraalkylammonium fluorides as initiators, and the resulting adducts were converted to difluoromethylated imines in the presence of excess fluoride. The imines were reduced to difluoromethylated amines using sodium borohydride.     

一种高效简易的聚(4-乙烯基三溴化吡啶)催化乙醇合成乙酸盐的方法(英文)

Poly(4-vinylpyridinium tribromide) is an efficient catalyst for the conversion of various alcohols to their corresponding acetate derivatives with acetic anhydride.This method has some advantages such as mild reaction conditions,good to excellent yields,and ease of work-up.     

HPLC-MS investigations of acidic contaminants in ammunition wastes using volatile ion-pairing reagents (VIP-LC-MS)

In order to hyphenate ion pairing chromatography and MS detection we used several types of formates as volatile ion pairing reagents (IPRs) instead of common tetraalkylammonium salts, as these salts tend to precipitate in the ion source. The formates were prepared by mixing formic acid with the corresponding amine. Both tributyl- and trihexylammonium formate proved to be valuable IPRs for the separation of acidic compounds like nitrobenzoic acids, nitrobenzenesulfonic acids and nitrated phenols. Due to the weaker retention of the ion-pairs with trialkylammonium formates compared with tetraalkylammonium compounds, either less organic modifier or a higher concentration of the IPR had to be used. With negative atmospheric pressure chemical ionization mass spectrometry and electrospray ionization mass spectrometry it was possible to unambiguously identify several acidic oxidation products of 2,4,6-trinitrotoluene (TNT) in ammunition wastewater and soil extracts. 2-amino-4,6-dinitrobenzoic acid was often found to be the main metabolite of TNT in such water samples.     

二(1,3-二硫杂环戊烯-2-硫酮-4,5-二巯基)镉-季铵类配合物的合成与表征

二（１，３－二硫杂环戊烯－２－硫酮－４，５－二巯基）镉－季铵类配合物的合成与表征李洪启宋燕西＊周宏英王爱勤姚钟麒俞贤达（中国科学院兰州化学物理研究所，兰州７３００００；＊兰州大学化学系，兰州７３００００）关键词二（１，３－二硫杂环戊烯－２－硫酮－４，...     

Boron（Ⅲ） Tribromide or Tianium （Ⅳ） Bromide and Lewis Base Promoted Baylis—Hillman Reaction

It was found that,when the Baylis-Hillman reaction of arylaldehydes with methyl vinyl ketone was carried out at below -20℃ in the presence of boron (Ⅲ） tribromide or titanium (Ⅳ） bromide using a catalytic amount of Lewis base such as amine,the brominated compounds and the Baylis-Hillman adducts could be obtained as the major products in good yields for various aryl aldehydes.But at room temperature,the elimination products were the major products.In addition,the palladium catalyzed allylic substitution reactions of the elimination products were also examined.