Sodium reaction with bromine

When 3,4-disubstituted 4-aminoisoxazolin-5(4Af)-ones (9) are hydrogenated, and then subsequently recyclized, high yields of imidazoles (10) are obtained (Scheme 6.1.4). The starting materials can be readily made from isoxazolin-5(4Af)-ones by sequential bromination, reaction with sodium azide and conversion of azide into amino by reaction with hydrobromic acid in acetic acid. The amines are then converted into formamidine or acetamidine derivatives with DMF or dimethylacetamide under reflux in phosphoryl chloride-chloroform. Yields at this stage are 50-93%. Catalytic... 

Wang G-W, Gao J. Solvent-free bromination reactions with sodium bromide and oxone promoted by mechanical milling. Green Chem 2012 14 1125-31. 

Reaction of o-toluidine with chloral hydrate in presence of hydroxylamine hydrochloride and subsequent treatment with H2SO4 gave the isatin derivative 337. Bromination of 337 followed by reaction with sodium diethyl malonate gave 338. Catalytic reduction with Pd/C gave the oxoindole derivative 339 that upon hydrolysis with aqueous NaOH followed by... 

The first report of the use of bromine for the oxidation of sulphoxides appeared in 1966116. Diphenyl sulphone was isolated in 0.5-1% yield when the sulphoxide was treated with bromine in aqueous acetic acid for several hours. The yield was increased to about 5% by quenching the reaction with sodium carbonate. A kinetic study117 of a similar reaction involving dimethyl sulphoxide showed no significant yield improvement but postulated that the mechanism proceeds via an equilibrium step forming a bromosulph-onium type intermediate which reacted slowly with water giving dimethyl sulphone as indicated in equation (35). 

Bromine, reaction with phenylacetylene and sodium hydroxide to give phenylbromoethyne, 46, 86 N-Bromoacetamide, as reagent for bromofluorination of 1-heptene, 46,10... 

Bromide ion reacts with a dilute solution of sodium / -1 o 1 uc nc sulfo nc h 1 o ra -mide (chloramine-T) and is oxidized to bromine which readily reacts with phenol red at pH 4.5 to 4.7. The bromination reaction with phenol red produces a color that ranges from red to violet, depending on the concentration of bromide ion. An acetate buffer solution is used to maintain the pH between 4.5 and 4.7. The presence of high concentration of chloride ions in the sample may seriously interfere in the test. In such cases, the addition of chloride to the pH buffer solution or the dilution of the sample may reduce such interference effect. Remove free chlorine in the sample by adding Na C solution. In addition, the presence of oxidizing and reducing agents in the sample may interfere in the test. 

The liberated bromine is carried from the tower by means of a stream of air and into an absorber containing sodium carbonate solution. By reaction with sodium carbonate, the bromine is converted to sodium bromide and sodium bromate ... 

The mechanism of displacement of chlorine and bromine by fluoride from the side chain of these systems is of interest. It has been suggested that an Sn2 type of displacement of fluorine from 3-trifluoromethylquinoline occurs in reactions with sodium eth-oxide [141] (Figure 9.55), and a similar process could account for the displacements of chloride or bromide by fluoride from 9.54A that were indicated in Figure 9.54. 

Isomerically pure vinyl halides are important starting materials for preparation of the corresponding vinyl lithium species (see Section 7.1) and for use in Pd-catalyzed coupling reactions (see Section 7.10). Halogenation of vinylsilanes offers a valuable route for the synthesis of both (E)- and (Z)-vinyl halides. These reactions involve addition of the halogen to the double bond, followed by elimination of the silicon and halide moieties. The stereochemical outcome of the reaction will depend on both the mode of addition and the mode of elimination. For example, bromination of (Z)-vinylsilanes with bromine in CH2CI2 proceeds via an anti-addition. Treatment of the bromine adduct with sodium methoxide results in anti-desilicobromination. The conversion of the vinylsi-lane into the vinylbromide occurs with overall inversion of the double bond stereochemistry. " ... 

Dehydrohalogenation. a-Bromobenzalacetone has been prepared from benzal-acetone by addition of bromine and elimination of HBr by reaction with sodium... 

A few halogenated 3-pyrazolin-5-thiones are known (Table XVIII). These are prepared from the methyl chlorides of 3- or 4,5-dichloro-pyrazole by reaction with sodium sulfide or potassium hydrogen sulfide.795,981 Michaelis988,992 has reported that 3-pyrazolin-5-selenones form dichlorides and di- and tetrabromides when treated with chlorine or bromine. No specific structures were suggested. 

Reactions with electrophilic reagents take place with substitution at C-3 or by addition at the pyridine nitrogen. All the aza-indoles are much more stable to acid than indole (cf. 20.1.1.9), no doubt due to the diversion of protonation onto the pyridine nitrogen, but the reactivity towards other electrophiles at C-3 is only slightly lower than that of indoles. Bromination and nitration occur cleanly in all four parent systems and are more controllable than in the case of indole. Maniuch and Vilsmeier reactions can be carried out in some cases, but when the latter fails, 3-aldehydes can be prepared by reaction with hexamine, possibly via the anion of the azaindole. Alkylation under neutral conditions results in quatemisation on the pyridine nitrogen and reaction with sodium salts allows A-1-alkylation. Acylation under mild conditions also occurs at N-1. The scheme below summarises these reactions for the most widely studied system - 7-azaindole. Acylation at C-3 in all four systems can be carried out at room temperature in the presence of excess aluminium chloride. ... 

N-Bromosucdnimide in bromination of o-nitrotoluene to form < -nitro-benzyl bromide, 4G, 81 Butadiene, 46, 106 BuTADrVNE, DIPHENYL, 46, 39 A - -Bhtenolide, 46, 22 (-Butyl alcohol in synthesis of phenyl (-butyl ether, 46, 89 (-Butyl azidoacetate, 46, 47 hydrogenation of, 46, 47 (-Butyl chloroacetate, reaction with sodium azide, 45, 47 (-Butyl hypochlorite, reaction with cy-clohexylamine, 46,17 (-Butylthiourea, 46, 72 (-Butylurea, 46, 72... 

A very convenient method for the synthesis of (158) consists in the side-chain bromination of 2-thienyl ethyl ketone followed by reaction with sodium methoxide in methanol and with methanesulphonyl chloride in pyridine, which gave (157) in 88% yield. Treatment of (157) with calcium carbonate led to 1,2-rearrangement of the thienyl group to give (158). Metal complexes of s> -thiophen-2-aldoxime, thiophen-2-carbaldehyde 2-benzothiazolylhydrazone, and thiophen-2-carbaldehyde thiosemicarba-zone have been studied. 

ZINC CYANIDE (557-21-1) Zn(CN)j Noncombustible solid. May tend to be an unstable explosive. Reacts with acids, acid fumes, acid salts, or elevated temperatures releases flammable and poisonous hydrogen cyanide gas. Can react violently with magnesium (incandescence), chlorates, nitrates, perchlorates. Incompatible with nitrites, chlorates. Mixtures of metal cyanides with metal chlorates, nitrates, nitrites, or perchlorates may cause violent explosions. Incompatible with strong oxidizers, bromine, chlorine, fluorine, mercurous chloride, nitric acid. Violent reaction with sodium nitrite. Forms sensitive explosive mixtures with potassium chlorate. ZINC DIACETATE (557-34-6 5970-45-6, dihydrate) Zn(C2H302)2 Noncombustible... 

Sulphonyl halides, other than fluorides, have also been produced by halide exchange. Thus, sulphonyl chlorides may be made from the fluoride by refluxing with aluminium trichloride622,623. Sulphonyl bromides may be prepared from the sulphonyl chloride by reaction with sodium sulphite and base, followed by bromine (equation 158)624... 

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