Hydroxides separation

To obtain optically pure I- and daec.-octyl alcohols, steam distil the respective esters with 30 per cent, sodium hydroxide solution use the proportions 1 mol of ester to 2 mols of sodium hydroxide. Separate the alcohols from the steam distillate, dry over anhydrous potassium carbonate, and distil under diminished pressure. Both samples boU at 86°/20 mm. (9) and have the following rotations ... 

Analyses of alloys or ores for hafnium by plasma emission atomic absorption spectroscopy, optical emission spectroscopy (qv), mass spectrometry (qv), x-ray spectroscopy (see X-ray technology), and neutron activation are possible without prior separation of hafnium (19). Alternatively, the combined hafnium and zirconium content can be separated from the sample by fusing the sample with sodium hydroxide, separating silica if present, and precipitating with mandelic acid from a dilute hydrochloric acid solution (20). The precipitate is ignited to oxide which is analy2ed by x-ray or emission spectroscopy to determine the relative proportion of each oxide. 

Lithium may be recovered from natural chloride brines. Such recovery processes may require additional steps depending on the magnesium and calcium content of the brine. The process involves evaporation of brine, followed by removal of sodium chloride and interferring ions such as calcium and magnesium. Calcium is removed by precipitation as sulfate while magnesium is removed by treating the solution with lime upon which insoluble magnesium hydroxide separates out. Addition of sodium carbonate to the filtrate solution precipitates hthium carbonate. 

Dipyridino-palladic Chloride, [Pd py2]Cl4, is formed by the action of chlorine on dichloro-dipyridino-palladium suspended in chloroform. It crystallises in small orange-coloured prisms, and rapidly loses chlorine on exposure to moist air. If heated with potassium hydroxide a brown precipitate of palladic hydroxide separates, and if this is carefully neutralised with hydrochloric acid, potassium chloro-palladate crystallises out. Treatment with an aqueous solution of potassium iodide decomposes the salt, with formation of the palladous compound thus ... 

Tetrammino-platinous Hydroxide, [Pt(NH3)4](OH)2, the base of the series, is isolated by treating a solution of tlie sulphate with baryta. The liquid is filtered and evaporated in vacuo, when the hydroxide separates in white deliquescent needles. It is a strong base, absorbs carbon dioxide from the air, displaces ammonia from its salts, and precipitates metallic hydroxides from solution of their salts. It decomposes at 110° C., and ammonia is not liberated from it by potassium hydroxide. 

It is good practice to dissolve sodium hydroxide separately in a small amount of cold water, then add the solution after the developing agent has been dissolved, stirring vigorously. 

The liquid, which had a reddish blue colour, becomes colourless, a clear brown, gelatinous precipitate of the hydroxide separating out. Since the hydroxide is soluble in excess of the potash, yielding a brown solution, care must be taken to add only the theoretical quantity required. Thorough washing with boiling water, in -which the precipitate is insoluble, is desirable to remove all traces of potassium chloride. 

What is the thermal effect produced by dissolving potassium nitrate and potassium hydroxide separately in water ... 

On shaking iron pentacarbonyl with a dilute solution of hydrogen peroxide, colloidal ferrous hydroxide separates. 

The copper salt separates and the whole is poured into 8000 c.c. of ether, the brisk red precipitate collected, washed with ether, and dried in vacuo. The operations are best conducted in an atmosphere of carbon dioxide or nitrogen. The product is a red to orange-yellow i>owder, moderately soluble in water, readily soluble in glj cerine and glycol, also in 2A sodium hydroxide. In the latter case no copper hydroxide separates unless the solution is heated. 

Although the enhanced speed of reaction in the highly polar, aprotic solvent makes it possible to effect the reaction in the minimum time, if the optimum yield of product is also desired it is preferable for the concentration of ions in the solvent not to exceed 1 molar. Preferably the concentration of these ions is maintained as low as possible by slowly adding the catechol... to the reaction mixture. During the course of this slow addition the ions react as they are formed, and are therefore always present in a very high dilution. When the alkaline conditions needed for the reaction are provided by the addition of an alkali metal hydroxide to the reaction mixture, it is usually most convenient and satisfactory to add the catechol... and the alkali metal hydroxide separately, simultaneously and slowly to a solution of methylene chloride in the highly polar, aprotic solvent. 

Fig. 5-29. Separation of tetramethylammonium hydroxide. - Separator column IonPac NS1 (10pm) eluent 0.001 mol/L hexanesulfonic acid / acetonitrile (94 6 v/v) flow rate 1 mL/min detection suppressed conductivity injection volume 50 pL solute concentration 20 ppm.

Add 2500 cm of 0.1 N NH4 solution at 6 cm per minute to 5000 cm of 0.1 A/Cr(NOj)j 9HjO at 20 C with stirring. The original precipitate disappears after about 2 hr, but a permanent precipitate forms later. At this point, add the rest of the alkali rapidly. Dark green hydroxide separates as a gelatinous precipitate. Allow the precipitate to settle and decant the supernatant liquid as completely as possible. 

Heat oil and water phases (except potassium hydroxide) separately to 65°-70°C. 

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