Bromides, acid preparation

The synthesis of these disubstituied thioureas takes place in three steps. First the alkyl bromide is prepared by the action of hydrobromic acid on the corresponding alcohol (518). Then the dialkylcyanamide is obtained by treatment at 25°C with calcium cyanamide. The yields are of the order of 30 to 60%. Thioureas are obtained in a third step from the cyanamide by reaction at 40 C with HjS in the presence of pyridine. Yields ranged from 57 to 90% (518),... 

Cadmium Bromide. The hydrated bromide is prepared by dissolution of cadmium carbonate, oxide, sulfide, or hydroxide in hydrobromic acid. The white crystalline material is cadmium bromide tetrahydrate [13464-92-1], CdBr2 4H2O, Ai/ 29s —1492.55 kJ/mol (—356.73 kcal/mol) (3)... 

The manufacture of the cyclohexyl analog is as follows. Phenyl magnesium bromide was prepared from 48.5 g (0.308 mol) of bromobenzene, 7 g (0,29 mol) of magnesium, and 125 ml of dry ether. To it was added at 5°C over a period of A hour 40 g (0.18 mol) of cyclohexyl (3-(N-piperidyl)-ethyl ketone (BP 115° to 117°C/1 mm) in 125 ml of dry ether. The mixture was allowed slowly to come to room temperature, refluxed for one hour, and then poured into ice containing 80 ml of concentrated hydrochloric acid. Ammonium chloride (100 g) and 200 ml of concentrated ammonium hydroxide were added and the organic layer was separated. After drying and removing the solvent, the residue was distilled under reduced pressure. The base distilled at 158° to 170°C (1 mm) and solidified. Upon recrystallization from methanol it melted at 112° to 113°C. 

When a solution of hydrogen bromide is prepared, 1.283 L of HBr gas at 25°C and 0.974 atm is bubbled into 250.0 ml of water. Assuming all the HBr dissolves with no volume change, what is the molarity of the hydrobro-mic acid solution produced ... 

C. Oligo- and Poly-nucleotides.—The stepwise enzymatic synthesis of internucleotide bonds has been reviewed. A number of polynucleotides containing modified bases have been synthesised " in the past year from nucleoside triphosphates with the aid of a polymerase enzyme, and the enzymatic synthesis of oligodeoxyribonucleotides using terminal deoxynucleotidyl transferase has been studied. Primer-independent polynucleotide phosphorylase from Micrococcus luteus has been attached to cellulose after the latter has been activated with cyanogen bromide. The preparation of insolubilized enzyme has enabled large quantities of synthetic polynucleotides to be made. The soluble enzyme has been used to prepare various modified polycytidylic acids. ... 

Hydrogen bromide is prepared in situ by heating sodium bromide and concentrated sulphuric acid ... 

The aryl bromide 40, prepared from cross-coupling between 1,2-dibromobenzene and (trimethylsilyl)acetylene, was converted to the corresponding arylzinc halide 41a and arylboronic acid 41b for subsequent coupling with the haloallenes 42 to produce the benzannulated enyne-allene 43 in -40% yield (Scheme 20.10) [38]. Desilylation with tetrabutylammonium fluoride (TBAF) then afforded 44 in 67% yield. 

K. Bock, I. Lundt, and C. Pedersen, Reaction of aldonic acids with hydrogen bromide. I. Preparation of some bromodeoxyaldonic acids, Carbohydr. Res., 68 (1979) 313-319. 

Barium bromide is prepared by the reaction of barium carbonate or barium sulfide with hydrobromic acid ... 

Cadmium bromide is prepared by heating cadmium with bromine vapor. Also the compound can be prepared by the treatment of dry cadmium acetate with glacial acetic acid and acetyl bromide. Alternatively, it may be obtained by dissolving cadmium or cadmium oxide in hydrobromic acid and evaporating the solution to dryness under hehum in an inert atmosphere. 

Lead bromide is prepared by treating an aqueous solution of lead nitrate with hydrobromic acid or with sodium or potassium bromide ... 

Lithium bromide is prepared by neutralizing lithium hydroxide or hthium carbonate with an aqueous solution of hydrobromic acid, followed by concentration and crystallization ... 

Magnesium bromide is prepared by treating magnesium oxide with hydro-bromic acid and subsequent crystaUization above 0°C. The product is hexahydrate, MgBr2 6H20 ... 

To the crude mixture of ammonium bromide and /3-bromo-propionic acid, prepared as described on p. 25, from 317 g. of ethylene cyanohydrin, are added 1200 cc. of carbon tetrachloride and 200 cc. of the same solvent which has been shaken with the aqueous distillates the ammonium bromide is filtered off and washed with 200 cc. of carbon tetrachloride. The watery layer, amounting to about 350 cc., is separated and shaken with 100 cc. of carbon tetrachloride. To the united carbon tetrachloride solutions are added 450 cc. of 95 per cent ethyl alcohol and 10 g. of sulfosalicylic acid or phenolsulfonic acid to act as a catalyst (Note 1). 

Trihydrazino-nickel Chloride, [Ni(N2H4)3]Cl2, is obtained by treating hexammino-niekel chloride with 50 per cent, aqueous hydrazine hydrate. On heating the mixture ammonia is evolved, and the hydra-zino-salt precipitated as a violet crystalline powder which dissolves in dilute acids, giving a blue solution. The corresponding hy drazino -compounds of nickel bromide are prepared in the same manner from nickel bromide and hexammino-niekel bromide. They are crystalline substances, and resemble the clilorides in appearance and in reactions. 

Synthesis of Acid-Prepared Mesoporous Spheres (APMS).3 Tetraethylorthosilicate (TEOS, 5.65 g, 27.1 mmol) was added to a solution of cetyltrimethylammonium bromide (CTAB, 1.20 g, 3.30 mmol) in aqueous acid (4.40 g cone. HC1, 55.5 g H20). This mixture was stirred for 1 hour and then transferred to a teflon-lined Parr autoclave and heated at 150 °C for 40 minutes. The mixture was cooled and filtered to recover a white powder. APMS could also be prepared at temperatures between 80 and 230 °C by adjusting the heating time (lower temperatures, longer times). 

The Grignard reagent—magnesium phenyl bromide—is prepared as described in Preparation 21 from 1-2 gms. (1 mol.) of dry magnesium and 8 gms. (1 mol.) of dry bromobenzene. 6-8 gms. (1 mol.) of dry methyl benzoate dissolved in 25 gms. of sodium-dried ether are added to the cold solution, slowly and with constant shaking. The liquid is then heated on a water bath until no further change takes place. Ice and dilute sulphuric acid are added to the cold reaction mixture, which, when the precipitate has dissolved, is steam distilled. The triphenyl carbinol which remains is recrystallised from benzene. 

Reaction XLVm. (a) Action of Alkali Cyanides on Alkyl and Acyl Halides. (Bl., [2], 50, 214.)—This reaction is capable of very wide application, all the simple alkyl halogen compounds, the acyl halides, and the halogen fatty acids come within its scope. The nitriles so formed yield acids by hydrolysis, so it is frequently the first step in the synthesis of an acid—the preparation and hydrolysis of the nitrile are often combined. The preparations of malonic, succinic, tricarballylic and other acids (Preparations 60, 61, 62) illustrate this. The extension of this reaction to acyl halides is important, and should be referred to, as should the interaction of silver cyanide, and alkyl iodides, to give isonitriles. Mercuric and silver cyanides, it may be noted, give with acyl chlorides and bromides better yields of normal acyl nitriles than do the alkali cyanides. 

By interaction of 7-amino-8-oxo-3-vinyl-5-thia-l-azabicyclo(4.2.0)oct-2-ene-2-carboxylic acid 4-methoxyphenyl ester with 4-bromoacetyl bromide was prepared 7-(4-bromo-3-oxo-butyrylamino)-8-oxo-3-vinyl-5-thia-l-azabicyclo (4.2.0)oct-2-ene-2-carboxylic acid 4-methoxyphenyl ester. The active methylene group in that product was then nitrosated with sodium nitrite. The initial product spontaneously tautomerizes to afford 7-(4-bromo-2-hydroxyimino-3-oxo-butyrylamino)-8-oxo-3-vinyl-5-thia-l-azabicyclo(4.2.0) oct-2-ene-2-carboxylic acid 4-methoxyphenyl ester. By the reaction of that compound with thiourea and then with trifluoroacetic acid was obtained (6R,7R)-7-(2-(2-amino-4-thiazolyl)glyoxylamido)-8-oxo-3-vinyl-5-thia-l-azabicyclo(4.2.0)oct-2-ene-2-carboxylic acid sodium nitrite, (Z)-oxime (Cefdinir sodium nitrile). 

Molybdenum (II) bromide was prepared first by Blomstrand8 by passing bromine vapor over heated molybdenum. Lindner et al.9 then improved the method by using bromine vapor diluted with nitrogen. More recently Sheldon10 converted molybdenum(II) chloride to the bromide by fusion with lithium bromide. Like the chloride, molybdenum(II) bromide is usually an amorphous powder however, crystalline samples have been prepared by disproportionation of molybdenum (III) bromide under vacuum at 600°C.1 Our method is substantially that of Sheldon and consists of heating an intimate mixture of molybdenum (II) chloride and a large excess of lithium bromide under vacuum. The crude product that results is dissolved in dilute sodium hydroxide and precipitated in pure form with concentrated hydrobromic acid. 

Summary Nitroethane is readily prepared by condensing ethyl bromide with sodium nitrite. The ethyl bromide can be made on site by the interaction of ethyl alcohol with potassium or sodium bromide in the presence of concentrated sulfuric acid. The ethyl bromide once prepared, can be purified by distillation. Once the reaction between the ethyl bromide and sodium nitrite is complete, the reaction mixture is extracted with ether, the ether removed, and the resulting remaining nitroethane then distilled to recover the purified product. 

A solution of phenylmagnesium bromide is prepared from magnesium (0.54 g, 22 mmol) and bromobenzene (2.20 ml, 21 mmol) in diethyl ether (20 ml). The solution is stirred under reflux as a solution of chalcone (1,3-diphenylpropenone) (2.0 g, 10 mmol) in diethyl ether (15 ml) is added dropwise. The mixture is stirred under reflux for 5 min after the addition is complete, and then allowed to cool. 6M-Hydrochloric acid is added dropwise until two clear layers form. The layers are separated and the aqueous layer is extracted with ether (10 ml). The organic layers are combined, dried (MgS04), and the solvent is evaporated. The residue is recrystallized from methanol (20 ml), to give 1,2,2-triphenylpropan-l-one (1.97 g, 69%), m.p. 92-94°. 

Sodium bromide, NaBr.—The bromide is prepared by neutralizing sodium hydroxide or carbonate with hydrobromic acid or by the action of bromine on sodium hydroxide, the bromate simultaneously formed being subsequently reduced by heating with charcoal ... 

The use of sodium bromide, sulfuric acid, and water is satisfactory in the preparation of low-molecular-weight compounds such as n-butyl bromide and trimethylene bromide, but this procedure leads to comparatively low yields of high-raolecular-weight bromides. The higher primary bromides are prepared more conveniently by saturating the alcohol at 100-120° with dry hydrogen bromide. ... 

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