Aqueous bromide extraction

A Kinetic Model. The shapes of the Arrhenius curves in Figure 1 are indicative of the mechanism of aqueous ion extraction. A closer examination of the shapes entails a detailed mathematical analysis of the kinetics of the elementary steps comprising the aqueous bromide extraction process. A rate equation will be derived here in order to interpret the experimental data in... 

Aqueous Bromide Extraction. It was observed that deviations from linearity at the low temperature end of the Arrhenius plots in Figure 1 were due to higher levels of extracted bromide. Among the experimental resins,... 

Sea water contains aqueous bromide ions. Chlorine gas is used in the extraction of bromine from this source. 

The TPA process. The technology involves the oxidation of p-xylene, as shown already in Figure 18—2. The reaction takes place in the liquid phase in an acetic acid solvent at 400°F and 200 psi, with a cobalt acetate/ manganese acetate catalyst and sodium bromide promoter. Excess air is present to ensure the p-xylene is fully oxidized and to minimize by-products. The reaction time is about one hour. Yields are 90—95% based on the amount of p-xylene that ends up as TPA. Solid TPA has only limited solubility in acetic acid, so happily the TPA crystals drop out of solution as they form. They are continuously removed by filtration of a slipstream from the bottom of the reactor. The crude TPA is purified by aqueous methanol extraction that gives 99 % pure flakes. 

Vinylic tellurides (generalprocedure) Elemental Te (0.6 g, 5.0 mmol) is added to a solution of the vinylic magnesium bromide (5.5 mmol) in THE (10 mL) under reflux and N2 atmosphere, and the reflux maintained for 20 min. The mixture is allowed to reach room temperature and then treated with n-butyl bromide (0.7 g, 5.0 mmol). After stirring for 10 min, the reaction mixture is cooled at 0°C, treated dropwise with saturated aqueous NH4CI, extracted with ether, dried (MgS04) and then evaporated. Kiigelrohr distillation of the residue under vacuum gives the vinyl alkyl tellurides as yellow liquids. 

A pressure vessel containing a tyrosine derivative dissolved in dimethyl formamide containing 2 (2 eq) was treated with the dropwise addition of ethyl bromide (1.1 eq) and then heated to 60°C for 30-minute intervals while being monitored by thin-layer chromatography (TLC). The reaction was then quenched with water and the aqueous layer extracted and then dried over Na2S04. The mixture was filtered, concentrated, and the product isolated. 

A solution of 16.2 g methyltriphenylphosphonium bromide in 200 mL anhydrous THF was placed under a He atmosphere, well stirred, and cooled to 0 °C with an external ice water bath. There was then added 30 mL of 1.6 N butyllithium in hexane which resulted in the generation of a clear yellow solution. The reaction mixture was brought up to room temperature, and 7.0 g 3,4-diethoxy-5-(methylthio)benzaldehyde in 50 mL THF was added dropwise, dispelling the color, and the mixture was held at reflux on the steam bath for 1 h. The reaction was quenched in 800 mL HzO, the top hexane layer separated, and the aqueous phase extracted with 2x75 mL of petroleum ether. The organic fractions were combined and the solvents removed under vacuum to give 12.0 g of the crude 3,4-diethoxy-5-methylthiostyrene as a pale amber-colored oil. 

Effect of 0.7 M 2-hydroxy-5-nitrobenzyl bromide (HNBB) on bubble production in buffered agarose gels (0.3% w/w, 0.27 ml) containing aqueous soil extract. (Taken from ref. 231.)... 

To this stirred solution of 2-lithiobomene is added, via syringe, 15.2 g (0.11 mol) of butyl bromide (Note 7) over a 1-min period. The ice bath is then removed, and the reaction mixture is stirred at room temperature overnight. The mixture is poured into 500 mL of water. The layers are separated and the aqueous layer extracted with two 100-mL portions of ether. The combined organic extracts are washed with five 200-mL portions of water, one 50-mL portion of 1 N hydrochloric acid, and two 200-mL portions of water. The solution is dried over anhydrous magnesium sulfate, filtered, and concentrated on a rotary evaporator at aspirator pressure and room temperature. Distillation of the residual yellow liquid through a 20-cm Vigreux column affords 8.9-9.4 g (50-53%) of product as a colorless liquid, bp 57-59°C (0.5 mm), nl5 1.4664, [a],2,5 - 10.7° (c MeOH, 0.0747) (Note 8). 

Methyl magnesium chloride (3 M) in THF was added to copper(I) bromide-dimethyl sulphide dissolved in 45 ml THF at — 20°C and after 20 minutes treated dropwise with the Step 1 product (0.014 mol) dissolved in 20 ml THF over 10 minutes. The mixture was stirred 2.5 hours and then quenched with saturated NH4C1 solution. The layers were separated and the aqueous portion extracted with diethyl ether. The combined organic phases were washed with 1M HC1, 5% aqueous NH4OH, dried with MgS04, concentrated, and the product isolated in 88% yield as a white solid. 

To 3-methyl-oxetane methanol (20.4 g) was added 50% aqueous NaOH (268 g), NBU4CI (2.8 g) and 300 ml hexane at ambient temperature. Thereafter, allyl bromide (19.4 g) was added drop wise and the solution refluxed 2 hours. The solution was cooled, the phases separated, and the aqueous phase extracted with EtOAc and added to the organic phase. The solvent was removed by distillation and the product isolated in 61% yield in 98% purity. H-NMR data supplied. 

To a suspension of cuprous iodide (0.03 mol) in 100 ml THF was added 25 ml dimethyl sulfide. The solution was cooled to -78 °C, phenyl magnesium bromide (0.06 mol) dissolved in diethyl ether added, stirred one hour, and 2-cyclohexenone (0.03 mol) dissolved in 10 ml THF added. The mixture was warmed to 0°C over 2 hours then re-cooled to -78 °C. It was treated with 15 ml hexamethyl-phosphoramide, stirred 30 minutes, treated with methyl cyanoformate (0.09 mol), and warmed to ambient temperature overnight. The mixture was poured into 100 ml 2M HCl, the organic phase separated, and the aqueous phase extracted with CH2CI2. The combined organic extracts were concentrated, the residue triturated with NH4CI, water, brine, dried, and 3.2 g product isolated as an oil. 

Phenylmagnesium bromide is prepared in the usual manner [Org. Syntheses Coll. Vol. 1, 226 (1941)] from 24 g. (1.0 gram atom) of magnesium and 157 g. (1.0 mole) of bromobenzene. To the ethereal solution of the Grignard reagent is added slowly 79 g. (1.0 gram atom) of selenium. The mixture is heated to reflux for 30 minutes and hydrolyzed with excess dilute hydrochloric acid. The ether layer is separated and the aqueous layer extracted with ether. The com-... 

Because of the hygroscopic nature of cyclopropyltriphenylphosphonium bromide (13) use of the tetrafluoroborate salt 16 is recommended. This salt may be prepared in 93% yield by dissolution of the bromide salt and excess sodium tetrafluoroborate in aqueous methanol. Extraction of the aqueous methanolic solution with chloroform, and evaporation of the dried chloroform solution, yields pure tetrafluoroborate salt 16. ... 

To a stirred solution of the epoxide (3.50 g, 40.6 mmol) and CuCN (364 mg, 4.06 mmol) in dry THF (30 mL) was added a 1 M solution of vinylmagnesium bromide in THF (52.8 mL, 52.8 imnol), over 45 min, dropwise at -78 °C. The mixture was allowed to warm up to 0 °C before it was quenched with a saturated aqueous NH4CI solution (20 mL). The layers were separated, the aqueous layer extracted with ether (3 x 50 mL), and the combined ethereal extracts were washed with brine (20 mL) and dried (MgSO4). Evaporation of the solvent and chromatographic purification of the crude product (silica, Et2O pentane 1 3) gave the alcohol as a pale yellow oil (4.41 g, 95%). 

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