Effect of surfactant structure on catalysis of microemulsion for photoisomerization of trans-stilbene

In this study,the photoisomerization of trans-sfilbene was carried out in water in oil (W/O) microemulsions by using sodium dodecyl sulfate (SDS),dodecyl trimethyl ammonium bromide (DTAB) and cetyl trimethyl ammonium bromide (CTAB) as surfactant,respectively.The catalytic effect of microemulsion on this reaction is closely related to the structure of surfactant.When there is no photosensitizer 9,10-dicyanoanthracene (DCA),the surfactant with shorter hydrophobic chain is preferred,while in the presence of DCA,the surfactant with anionic polar group is preferred.     

Facile Formation of Ytterbium Diiodide and Its Use in the Synthesis of Allyl Selenides

Ytterbium metal reacts with iodine to generate ytterbium diiodide directly,which can react with diselenides to form ytterbium selenolates(RSeYbI2).These species reacted smoothly with allyl bromide to give allylselenides in moderato to good yields under neutral conditions.     

The Synthesis of Polyfluoroalkylbiphenyl

Polyfluoroalkylated biphenyl was obtained from reaction of benzene with R_FI/Na_2S_2O_4 using cetyltrimethylammonium bromide (CTAB) as PTC followed by dehydrogenation with DDQ in 38-43% yield.     

Tetrahydrofuran Ring—opening with Acyloxyphosphonium Bromde Catalyzed by Zinc Bromide：An Effective Method for the Preparation of 4—Bromobutyl Esters

Catalyzed by zinc bromide,tetrahydrofuran ring can be opened with acyloxyphosphonium bromide generated in situ to afford 4-bromobutyl esters under mild conditions in good to excellent yields.     

Regioselective synthesis of linalyl compounds via addition reaction of geranyl bromide and tin with carbonyl compounds

Linalyl alkyl or aryl carbinols were regioselectively synthesized by the reaction ofgeranyl bromide and powdered tin with aldehydes and ketones.     

Mono-Allylation of Gem-Diacetates with Allylsamarium Bromide

Our group have explored the reaction of allylsamarium bromide with a variety of substrates, such as N-(2-aminoalkyl)benzotriazoles1, imines2, nitriles3, diorgano diselenides4, disulfides5, isocyanates6 and nitroalkenes7. Here we wish to report the monoallylation of gem-diacetates with allylsamarium bromide. Gem-diacetates are stable in neutral and basic media, thus they are frequently used to protect aldehydes8. However, the presence of two leaving groups at the same carbon may make carbon …     

Synthesis and reactivity of 3-(trichlorogermyl)propanoic acid and 3-(triphenylgermyl) propanoic acid

3-(Trichlorogermyl)propanoic acid (la) reacts with phenylmagnesium bromide in malar ratio 1:4 to give 3-(triphenylgermyl)propanoic acid (2a).In the compounds la and 2a theβ-carboxylic functional group shows some unusual properties when they react with excess of phenylmagnesium bromide.The compound la reacts with phenylmagnesium bromide in molar ratio 1:5 to give phenyl 2-(triphenylgermyl)ethylketone (3a) and in molar ratio 1:6 to give l,l-diphenyl-3-(triphenylgermyl)propanol (4a).The compound 2a reacts with phenylmagnesium bromide in molar ratio 1:2 to give 3a and in molar ratio 1:3 to give 4a also.Dehydration of the compound 4a with dilute hydrochloric acid seems especially easy.Moreover,the compound la reacted with phenylmagnsium bromide in molar ratio 1:6,then the mixture was treated with dilute hydrochloric acid to give 1,1-diphenyl-3-(triphenylgermyl)-1-propene (5a) in one pot reaction.Alkyl Ge-C bond in the compound 5a can be cleaved selectively by lithium aluminium hydride ( LiAlH4) in good yiel     

O—Maltosylation of Heterocyclic Ketene Aminals

The stereoselective synthesis of O-maltosides by reacting benzoyl-substituted heterocyclic ketene aminals 1 or 2 with acetylated maltosyl bromide 3 was investigated.Compounds 1 or 2 reacted with 3 in the presence of mercuric cyanide to give O-maltosides 4 or 5 with E-configuration.While 1 reacted with 3 in the presence of calcium hydride to give O-maltosides 6 with Zconfiguration.     

PENTAFLUOROBENZENESULFONYL BROMIDE AND ITS REACTIONS

Pentafluorobenzenesulfonyl bromide was synthesized by the reaction of pentafluorophenylmagnesium chloride with sulphur dioxide followed by bromine oxidation. The sulfonyl bromide reacted with polyfluorophenoxide to form polyfluorophenyl pentafluorobenzenesulfonates. Photolysis of pentafluorobenzenesulfonyl bromide gave bis(pentafluorobenzene)sulfone and decafluorodiphenyl.     

The reaction of perfluoroalkanesulfonyl halides Ⅶ. Preparation and reactions of trifluoromethanesulfonyl bromide

The reaction between sodium trifluoromethanesulfinate, which was prepared from trifluorome-thyl bromide, with bromine in aqueous solution resulted in the formation of trifluoromethanesulfonylbromide (CF_3SO_2Br). CF_3SO_2Br reacted with alkenes and alkyne to give the corresponding adductswith the loss of SO_2 in good yields, and with compounds containing active hydrogen to give brominatedderivatives. A radical reaction mechanism was proposed and confirmed by EPR study.     

Reactions in microemulsion media. Nucleophilic displacement reaction of benzyl chloride with bromide ion

A kinetic and synthetic study of the reaction of benzyl chloride with bromide ion has been performed in microemulsions composed of cetyltrimethylammonium bromide, 1-butanol, water, potassium bromide, and hexane; rates and yields of benzyl bromide formation decreased with increasing hexane content.     

Stability and microtox response of butenyltin compounds

Tributenyltin bromides containing double bonds at carbon atoms C-1, C-2 or C-3 were synthesized from symmetrical tetrabutenyltins. Although all three tetrabutenyltin compounds were stable, only the tributenyltin bromides with double bonds at C-1 and C-3 were sufficiently stable for further studies. In aqueous sodium bromide (NaBr) solution containing 1% acetone, tri-1-butenyltin bromide was more stable in sunlight than tri-3-butenyltin bromide, yet neither compound was as stable as tributyltin bromide. Stability in seawater, in the absence of ultraviolet (UV) light, was less for both tri-1-butenyltin bromide and tri-3-butenyltin bromide than for tributyltin bromide. The relative toxicities of the tributenyltin bromides were determined using a bioluminescent bacteria assay. The concentrations of tributenyltin bromides necessary to produce a toxic response were three to six times greater than for tributyltin bromide.     

The constitution of the grignard reagent VII. The degree of association of ethylmagnesium compounds in diisopropyl ether

The degrees of association of ethylmagnesium bromide, diethylmagnesium and of a mixture of diethylmagnesium and magnesium bromide in the weakly basic solvent diisopropyl ether have been measured at concentrations up to 0.040 M at 27.7°. It is concluded that: (1), ethylmagnesium bromide is present as a dimer, (2), diethylmagnesium is present in a dimer-tetramer equilibrium with K₁ = 24.9 1/mol, and (3), when magnesium bromide is added to an excess of diethylmagnesium it reacts to form ethylmagnesium bromide. Diethylmagnesium and ethylmagnesium bromide are also in equilibrium with (EtMgBr·Et₂Mg), with K₃ approximately 2.5.     

Indium-mediated allylation/propargylation of α-diazoketones: a facile synthesis of 1-bromo-2-alkyl- or 2-arylpent-4-en-2-ols

α-Diazoketones undergo smooth allylation with successive bromide insertion with allylindium bromide generated in situ from allyl bromide and indium metal to produce 1-bromo-2-alkyl- or 2-arylpent-4-en-2-ols in high yields. Addition of propargylindium bromide produces 1-bromo-2-alkyl-or 2-arylpent-4-yn-2-ols under similar conditions.     

4－N－茄呢基氨基苯甲酸糖酯的合成

在氢氧化钠和四丁基溴化铵存在下，将化合物4－N－茄呢基氨基苯甲酸（3） 分别与O－乙酰基溴代葡萄糖、O－乙酰基溴代半乳糖、O－乙酰基溴代乳糖和O－乙 酰基溴代麦牙糖反应制得对应的糖酯4a-4d，由元素分析，IR，~1H NMR，~(13)C NMR和MS确证了四个新化合物的结构，并做了几种抗癌生理活性测试。     

模板剂对全硅MCM-41介孔分子筛结构的影响

分别采用十六烷基三甲基溴化铵和十六烷基三乙基溴化铵作为模板剂,硅溶胶为硅源,用水热晶化法在碱性（NaOH）介质中合成了MCM-41介孔分子筛样品.通过XRD、N2吸附-脱附、TG-DTA、IR等测试手段对这两种样品进行了对比表征分析.考察了两种不同模板剂对其晶体结构、比表面及孔径大小的影响.实验结果表明,相对于十六烷基三甲基溴化铵做模板剂,采用大头基的十六烷基三乙基溴化铵可以合成较大孔径和孔容（分别为4.72 nm和1.14 cm3•g-1）的MCM-41介孔分子筛,而且具有较窄的孔径分布,因此对于合成大孔径的介孔分子筛MCM-41,十六烷基三乙基溴化铵是一种很好的模板剂.     

Grignard试剂同6，6－二烷基富烯反应的研究

烯丙基卤化镁和环戊二烯基溴化镁同６，６－二烷基富烯分别进行富烯环外双键的加成和还原反应，生成的取代环戊二烯基负离子用（ＣｐＴｉＣｌ＿２）＿２Ｏ（Ｃｐ＝环戊二烯基）或ＴｉＣｌ４配合，合成通式为Ｃｐ（Ｃ＿５Ｈ＿１－ＣＲＲ￣１－ＣＨ＿２ＣＨ＝ＣＨ＿２）ＴｉＣｌ＿２和（Ｃ＿５Ｈ＿４ＣＨＲＲ￣１）＿２ＴｉＣｌ＿２的化合物。对烯丙基卤化镁、环戊二烯基溴化镁同富烯的反应机理进行了探讨。     

Regiochemical variation in the electrophilic addition of HBr to 1-phenylprop-1-yne

The reaction of aryl alkynes with dilute methylene chloride solutions of quaternary ammonium bromide and 20% trifluoroacetic acid produces primarily the syn Markovnikov adducts of hydrogen bromide. At moderate concentrations of the bromide, the principal product is the Markovnikov anti adduct. At high concentrations of bromide, the anti-Markovnikov anti addition product predominates.     

Synthesis of 2,3-Dihydro-1H-imidazo[1,2-a]pyridinium Systems by Halocyclization of 1-Alkenyl(propargyl)-2-aminopyridinium Halides

Russian Journal of General Chemistry - Reaction of 2-aminopyridine with allyl bromide, methallyl chloride, 2-bromoallyl bromide, and propargyl bromide in acetone furnished 2-amino-1-allyl-,...     

Molecular absorption spectrometry (MAS) by electrothermal evaporation in a graphite furnace-IX Determination of traces of bromide by mas of AlBr after liquid-liquid extraction of bromide with triphenyltin hydroxide

The determination of traces of bromide by molecular absorption spectrometry (MAS) of AlBr (with electrothermal volatilization) is described. It is possible to determine 25 ng of bromide. Many problems are caused by various matrices, so an extraction method for separation (and also preconcentration) was developed. The combination of bromide extraction with triphenyltin hydroxide, stripping with 0.025M barium hydroxide and determination of the extracted bromide by MAS of AlBr (after addition of aluminium ions) gives a very sensitive and selective method for determination of traces of bromide in micro or macro samples, in the presence of large amounts of other species, including chloride and iodide.