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.     

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     

Reaction of Polymer-supported Selenovinyl Bromide with Grignard Reagents： A Facile Route to the Synthesis of （E）-1, 2-Disubstituted Olefins

Polymer-supported selenovinyl bromide, easily prepared from polymer-supported selenenyl bromide with acetylene, reacts with different Grignard reagents using a step-by-step strategy to obtain （E）-1, 2-disubstituted ethenes in good yields.     

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.     

Lithium bromide catalyzed solvent free method for synthesis of 2-substituted benzimidazoles and imidazopyridines

<正>The first successful lithium bromide mediated solvent free condensation of arylenediamine and esters to obtain 2-substituted benzimidazole and imidazopyridine in good to excellent yields is described.     

Kinetic spectrophotometric determination of bromide in clidinium-c drug

A simple,rapid and sensitive method has been described for the determination of the trace amounts of bromide.The method is based on the catalytic effect of bromide ion on the oxidation of methylene blue by bromate in sulfuric acid media.The reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of methylene blue at 665 nm. Bromide was determined in the range of 0.05-1.90μg/mL with the detection limit of 0.03μg/mL.The relative standard deviations of five replicate determinations of 0.20 and 10.0μg/mL of bromide were 2.4%and 1.8%,respectively.The influence of potential interfering ions and substances was studied.The method is applied to the analysis of bromide in clidinium-c tablet as a real sample.     

An environmentally benign benzylic oxidation catalyzed by hypervalent iodine intermediate in water

An effective and environmentally benign benzylic oxidation for transition of alkylarenes into the corresponding carbonyl compounds was reported.Alkylarenes were mixed and stirred with potassium bromide,m-chloroperbenzoic acid and a catalytic amount of iodobenzene in water at 60 8C for several hours,a series of the corresponding carbonyl compounds was obtained in moderate to good yields.In the reaction,iodobenzene was first oxidized by m-chloroperbenzoic acid into the hypervalent iodine intermediate which then reacted with potassium bromide to form the key radical initiator for the benzylic oxidation.     

Heck Reaction Catalyzed by Palladacycle in Neat Water

Cydopalladated ferrocenylimine has been found to be a type of excellent phosphine-free catalyst for Heck reactions in neat water with both higher yields and turnover numbers than those reported in the literature up to now. Some commercial emulsifying agents, indodin~ the commonly used quaternary ammonium salts, have been proved to be excellent additives in the catalysis of the reactions. Not only aromatic iodide, but also aromatic bromide could be coupled with the olef‘ms. All rcactions were able to be conducted in air under refluxlng condition.     

Microwave Irradiated Reactions of N-Phenacylpyridinium Chloride with Aromatic Aldehydes and Ketones

Pyridinium cations show a great variety of synthetic applications,due to the aromatic character of the pyridine heterocycle, to its basicity, and the electron-attracting influence of the nitrogen atom1-3. N-phenacylpyridium bromide in the presence of base…     

Regioselective Propargylation of Aldehydes with Propargyl Bromide Mediated by Sn-In in Aqueous Media under Microwave Irradiation

Tin-indium were employed in the propargylations of various aldehydes with propargyl bromide in the presence of SnCl2 and C6H5（CH3）3NBr under microwave irradiation to afford the corresponding homopropargyl alcohols exclusively in high yields. All the reactions were completed smoothly in predominantly aqueous media in 200 seconds only.     

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.     

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.     

3,4-二羟基苯甲酸-BrO3——Fe(phen)32+-H2SO4体系中的振荡现象

在Belousov-Zhabotinsky(BZ)反应中,Br^-通常起控制作用,初始加入少量的Br^-可抑制振荡。     

高立体选择性地合成薄荷基溴和新薄荷基溴

薄荷基溴和新薄荷基溴是一类非常有用的不对称合成中间体。以L-薄荷醇为原料,通过与不同的溴化剂反应高立体选择性地得到薄荷基溴和和新薄荷基溴。当L-薄荷醇与盐酸和无水溴化锌反应时高立体选择性地得到薄荷基溴,当L-薄荷醇与三溴化磷反应时高立体选择性地得到新薄荷基溴.     

The reaction OF N‐dichlorophosphoryl‐ P‐trichlorophosphazene with alkyl grignard reagents

The reactions of N‐dichlorophosphoryl‐P‐trichlorophosphazene Cl₃PN P(O)Cl₂ ( 1 ) with benzylmagnesium bromide, 2‐phenylethylmagnesium bromide, trimethylsilylmethylmagnesium chloride, n‐butylmagnesium bromide, cyclohexylmagnesium bromide, cyclopentylmagnesium bromide, tert‐butylmagnesium bromide, iso‐propylmagnesium bromide, and ethylmagnesium bromide were studied. Tri‐ and pentaalkyl phosphazenes were obtained in very poor yield from trimethylsilylmethylmagnesium chloride and cyclohexylmagnesium bromide, respectively. Trialkylphosphoryl compounds formed from benzyl‐, 2‐phenylethyl‐, and n‐butylmagnesium bromide. No phosphorus compound could be isolated from the reaction of 1 with t‐butyl‐, cyclopentyl‐, iso‐propyl‐, and ethylmagnesium bromide. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:413–416, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10153     

Dosage polarographique du brome a l'echelle du nanogramme: Application à la determination du brome sanguin et urinairePolarographic determination of bromide at nanomolar levels. Application to the determination of bromide in blood and urine

Polarographic determination of bromide at nanomolar levels. Application to the determination of bromide in blood and urine.Colorimetric methods for bromide determination lack adequate sensitivity for normal levels in biological fluids. A sensitive amplification process is recommended: bromide is oxidized to bromate with hypochlorite; after reaction between bromate and excess of bromide, the bromine formed is extracted into chloroform and then reduced to bromide by ammonia; these different steps can be repeated. Alternating current polarography of bromate allows selective evaluation in biological fluids. The detection limit is 10^-6 M and can be reduced to 10^-9 M with further amplification steps. The effects of iodide and of instrumental parameters are discussed.     

Use of <Superscript>82</Superscript>Br and <Superscript>131</Superscript>I radionuclides in studies of goitrogenic effects of exogenous bromide

The interference of excessive bromide intake with iodine metabolism in the rat was studied using ⁸²Br and ¹³¹I radionuclides. Mainly lactating rat dams and their pups were used, in addition to adult male rats, in the present studies. Particularly, the influence of high bromide intake in lactating rat dams on the transfer of iodine and bromide to suckling young through breast milk was evaluated. The induction of hypothyroid status in the pups by high bromide intake in the mothers was proved unambiguously. Excessive bromide in lactating rat dams caused a marked decrease in plasma levels of thyroid hormones both, in the mothers and in their sucklings. The effects of an enhanced bromide intake on the thyroid function in relation to iodine status in the animals were also followed. Marked goitrogenic and thyrotoxic effects of excessive bromide in adult rats were significantly enhanced under the conditions of simultaneous iodine deficiency in the experimental animals.     

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.     

[Zn(NCS)4]2−-Selective electrodes based on higher quaternary ammonium salts (QAS)

We have studied analytical parameters of tetrarhodanozincate-selective film electrodes based on high-lipophilic quaternary ammonium salts: trinonyloctadecylammonium iodide, R-trioctadecylammonium bromide, R-trimethylammonium nitrate, R-tricetylammonium bromide, R-triethylammonium bromide, R-tributylammonium bromide, R-trilaurylammonium bromide, where R is 3,4,5-tris(dodecyloxy)benzyl. A procedure has been developed for the study of the molecular extraction of zinc rhodanide with membrane plasticizers. The applicability of these electrode to zinc determination in solid wastes has been demonstrated.     

An inexpensive modification of the Simmons-Smith reaction: The formation of bromomethylzinc bromide as studied by NMR spectroscopy

Bromomethylzinc bromide, prepared from zinc metal and methylene bromide in tetrahydrofuran, gives moderate to good yields of cyclopropanation product when treated with olefins, thus providing an inexpensive alternative to the Simmons-Smith procedure. An NMR study of the reaction between metallic zinc and methylene bromide has been carried out: in addition to bromomethylzinc bromide and dimethylzinc, two further species were observed and tentatively identified as bis(bromomethyl)zinc and a di- or tri-zinc compound.