Precipitation, with barium hydroxide

Upon boiling the precipitate with barium hydroxide solution, it passes into solution as lithium hydroxide (difference from magnesium). 

Other oxo acids of sulfur that are formed as by-products are precipitated with barium hydroxide, and BaS206-2H20 is then crystallized. Treatment of aqueous... 

Hydrolysis of Isouramil to Dialuric Acid (XII),—solution of one-half g. of isouramil in 10 cc. of dilute hydrochloric acid (1 1) was boiled for a few minutes and then cooled. A deposit of crystals weighing 0.25 g. was obtained, which melted at 214° (dec.) and gave a beautiful purple precipitate with barium hydroxide (which was not discharged by excess of the reagent). These properties characterized the product as dialuric acid. 

The normality or molarity of the acid can be determined by titration with a standard solution of sodium hydroxide using a color indicator, or by potentio-metric titration using a pH meter or a millivoltmeter. The sulfate anion in dilute acid can be measured by precipitation with barium chloride or by ion chromatography. 

Tetrammino-palladous Hydroxide, [Pd(NII3)4](OH)2, may be obtained by decomposing the sulphate with barium hydroxide. It separates as a colourless crystalline substance which is soluble in water and has a strong alkaline reaction. The aqueous solution is capable of precipitating copper, iron, cobalt, and nickel from solutions of their salts, and it also decomposes ammonium salts. 

Sulfite and sulfate ions were precipitated from the spent birch liquor (Fig. 1) with barium hydroxide. Monosaccharides and other low molar mass non-electrolytes and weak electrolytes were separated quantitatively from the lignosulfonates by means of ion exclusion chromatography (5). 

Anthraflavic and isoanthraflavic acids are detected by treating a little of the substance suspended in boiling water with barium hydroxide and filtering the liquid in presence of the above acid the filtrate is red and gives a yellow precipitate when neutralised with hydrochloric acid. 

In 1940, Murakami published a study21 of the constitution of verbascose. To prepare this sugar, Murakami extracted the finely ground roots with 95% alcohol, clarified the extract with lead acetate, and precipitated the verbascose with barium hydroxide and alcohol. After processing the barium complex in the usual way, and precipitating the saccharide several times from an aqueous solution by alcohol, Murakami obtained verbascose in 0.5-mm. spherocrystals composed of fine needles these had m.p. 253°, [a]20D + 170.2° (in water). The elementary analysis and the cryoscopic molecular-weight values were appropriate for a pentasaccharide. 

Oxidation of N-Acetyl-D-glucosylamine.98 Six grams (0.027 mole) of N-acetyl-D-glucosylamine (XLI) in 100 cc. of water is added to 18.5 g. (0.081 mole) of paraperiodic acid in 100 cc. of water, and the reaction mixture is maintained at 25° for four and one-half hours, which is known from analytical data obtained in small-scale experiments to be sufficient time for completion of the reaction with the consumption of two moles of the oxidant. The solution is exactly neutralized with barium hydroxide, the precipitate removed, and the filtrate evaporated to dryness in vacuum. The solid is extracted with 100 cc. of absolute ethanol, the ethanol extract evaporated to dryness, the residue taken up in ethanol, and the solution is centrifuged and again evaporated to dryness. The product, the dialdehyde XLII, can be converted into the corresponding barium salt (see reference 93). 

The presence of C02 can be confirmed with barium hydroxide solution, Ba(OH)2 a white precipitate of barium carbonate results. 

The resulting solution will contain saline impurities such as salts of iron and manganese derived from the barium peroxide. These can be removed by the addition of a little phosphoric acid followed by neutralisation with barium hydroxide solution when the metals are precipitated as phosphates. If necessary, further addition of barium hydroxide may be made m order to precipitate the hydrogen peroxide as pure barium peroxide, which on treatment with the correct quantity of dilute sulphuric acid will give a pure solution of hydrogen peroxide. 

For elements like radium, arsenic, beryllium, thallium, molybdenum and many others, not only the low solubility of the related minerals but also the coprecipitation or adsorption with other minerals, plays an important role. For instance radium is co-precipitated with iron hydroxides and barium sulfate. 

Fehling solution forms insoluble complexes with some mannans and xylans, and has been used for their purification. Erskine and Jones have recommended the use of cupric acetate and ethanol for this purpose. Fruc-tans can be precipitated with calcium or barium hydroxide, and it has been shown that mannans with the 2,3-cfs- and galactans with the 3,4-cis-glycol grouping unsubstituted are almost completely precipitated by barium hydroxide. ... 

The conductometric method may also be used in many titrations involving precipitations. For instance Harned13 has followed the conductance during the titrations of magnesium, nickel and cobalt sulphates with barium hydroxide. The resulting plots of the conductance against volumes of titrating fluid are all of the form shown in Fig. 9, two... 

In view of certain structural similarities, it is appropriate to consider these polysaccharides together. The acidic, capsular polysaccharide of Type III pneumococcus ([a]n —32.2° acid equivalent, 346 and nitrogen, 0.05%) is precipitable by barium hydroxide, heavy-metal salts, and hydrochloric acid. On acidic hydrolysis, it yields a small proportion of D-glucose together with an aldobiouronic acid identified as cello-biouronic acid [4-0-(/3-D-glucopyranosyluronic acid)-D-glucopyranose] by methylation and hydrolysis. Optical rotation data suggested that the... 

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