Rubidium carbonates

Rubidium carbonate (Rb Oj) is used to make special types of glass. 

Rubidium carbonate is used in special glass and in fiber optics. It enhances stability and durability of glass, reducing its conductivity. It also is used in the preparation of Rb metal and other rubidium salts. 

Rubidium carbonate is an intermediate in recovery of rubidium from lepi-dobte. The mineral, on prolonged heating with concentrated sulfuric acid, converts to alums. 

The mixed alum solution, on treatment with ammonia or potassium carbonate, forms carbonates of potassium, rubidium and cesium. Rubidium carbonate is separated from other alkab metal carbonates by fractional crystal-bzation (see Rubidium)... 

Rubidium may be analyzed in an aqueous solution of rubidium carbonate by AA, ICP-AES or other methods (see Rubidium). Carbonate anion, COs may be measured quantitatively by ion chromatography. Additionally, COs may be tested by treating Rb salt with a dilute acid. Liberation of CO2 with effervescence that turns lime water milky is a qualitative test. 

Rubidium chloride is prepared by adding hydrochloric acid to a solution of rubidium carbonate or hydroxide. The solution is evaporated to obtain well-defined colorless cubic crystals of rubidium chloride... 

Rubidium hydroxide is a stronger base than caustic soda or caustic potash. Its reactions are similar to theirs. Neutralization occurs with acids. Rubidium hydroxide absorbs carbon dioxide forming rubidium carbonate. 

Rubidium acid salts are usually prepared from rubidium carbonate or hydroxide and the appropriate acid in aqueous solution, followed by precipitation of the crystals or evaporation to dryness. Rubidium sulfate is also prepared by the addition of a hot solution of barium hydroxide to a boiling solution of rubidium alum until all the aluminum is precipitated. The pH of the solution is 7.6 when the reaction is complete. Aluminum hydroxide and barium sulfate are removed by filtration, and rubidium sulfate is obtained by concentration and crystallization from the filtrate. Rubidium aluminum sulfate dodecahydrate [7488-54-2] (alum), RbA SO 12H20, is formed by sulfuric acid leaching of lepidolite ore. Rubidium alum is more soluble than cesium alum and less soluble than the other alkali alums. Fractional crystallization of Rb alum removes K, Na, and Li values, but concentrates the cesium value. Rubidium hydroxide, RbOH, is prepared by the reaction of rubidium sulfate and barium hydroxide in solution. The insoluble barium sulfate is removed by filtration. The solution of rubidium hydroxide can be evaporated partially in pure nickel or silver containers. Rubidium hydroxide is usually supplied as a 50% aqueous solution. Rubidium carbonate, Rb2C03, is readily formed by bubbling carbon dioxide through a solution of rubidium hydroxide, followed by evaporation to dryness in a fluorocarbon container. Other rubidium compounds can be formed in the laboratory by means of anion-exchange techniques. Table 4 lists some properties of common rubidium compounds. 

A unique feature of azoles amongst five membered heterocycles is that they can act both as the carbon or the heteroatom donor during the bond formation. This possibility is frequently exploited in synthetic transformations. Pyrrole, for example, coupled effectively with bromoarenes in the presence of palladium based catalysts (6.67.), The use of PBuj as ligand and rubidium carbonate as base allowed for the reduction of catalyst loading to 1% without significant deterioration of the yield"... 

Watanabe99c improved the efficiency of the procedure by changing the ligand to and the base to rubidium carbonate. 

E. Muller made potassium iodate by electrolyzing the iodide. H. L. Wheeler 44 made rubidium iodate, RbI03, by the action of a mol. of iodine pentoxide on one of rubidium carbonate by treating a hot dil. soln. of iodine trichloride with rubidium hydroxide or carbonate by the action of iodic acid on a hot cone. soln. of rubidium chloride, RbCl. T. V. Barker obtained a good yield by passing chlorine into a hot cone. soln. of a mixture of rubidium iodide and hydroxide whereby the sparingly soluble iodate is precipitated. Caesium iodate, CsI03, was made in a similar way. 

An intimate mixture ot 274 grms. of rubidium iron alum, or 260 grms. of rubidium aluminium alum with 100 grms. of calcium carbonate, and 27 grms. of ammonium chloride, is heated in a nickel crucible to a dull red heat until ammonia vapours are no longer evolved, and then the temp, is raised to redness. The product is ground with a litre of cold water for 15 minutes filtered by suction and washed with 400 c.c. of water, added in small portions at a time. The combined sulphuric acid is precipitated by the addition of barium hydroxide, and the filtered liquid boiled while a stream of carbon dioxide is passed through the soln. If the soln. loses its alkaline reaction, and yet retains some calcium, a little rubidium carbonate must be added to precipitate calcium carbonate. The soln. is then treated with hydrochloric acid and evaporated. 

The alkali sulphates can also be made by neutralizing, say, a soln. of 5 grms. of sulphuric acid in 30 c.c. of water with the alkali hydroxide or carbonate, and evaporating the soln. until crystals begin to form. The process is not economical except on a small scale. It is used mainly for lithium, rubidium, and caesium sulphates. H. Erdmann 20 treated a hot soln. of crude rubidium iron alum with milk of lime made from purified lime, and filtered the liquid from the excess of lime, calcium sulphate, and ferric hydroxide, by suction. The small amount of lime in soln. is precipitated by adding rubidium carbonate. The filtrate is neutralized with sulphuric acid, and evaporated to the point of crystallization. 

T. Scheerer found that when heated to a yellow heat (c.1000°), in a closed platinum crucible, potassium carbonate loses about 0 5 per cent, in weight owing to the loss of carbon dioxide which is taken up again at lower temp. W. Dittmar could detect no change when heated to redness in an atm. of carbon dioxide, but it is partially converted into oxide in an atm. of nitrogen, and still more so in an atm. of hydrogen. P. Lebeau found that rubidium and caesium carbonates lose carbon dioxide when heated in vacuo, and, if the vacuum be maintained, decomposition is complete. P. Lebeau also found that the dissociation press, of rubidium carbonate is ... 

According to G. Kirchhoff and A. Bunsen, the evaporation of soln. of csesium or rubidium carbonates furnishes crystals of the hydrated salt. G. KirchhofE and R. Bunsen add that the crystals deliquesce rapidly in air, and when heated melt in their water of crystallization, and finally form the anhydrous carbonate as a white pulverulent mass, which rapidly deliquesces in air. The hydrated forms of rubidium and csesium carbonates have not been more closely investigated. 

R. Bunsen and G. Kirchhoff made rubidium hydrocarbonate, RbHC03, by evaporating over sulphuric acid, a soln. of rubidium carbonate in water sat. with carbon dioxide and in an atm. of carbon dioxide. Similar remarks apply to caesium hydrocarbonate, CsHC03. 

E. von Berg prepared colourless prismatic crystals of tetrahydrated trirubidium phosphate, Rb3P04.4H20, by crystallization, over sulphuric acid, of a soln. of two mols. of phosphoric acid, and three of rubidium carbonate, and he obtained crystals of pentahydrated tricsesium phosphate, Cs8PC>4.5H20, in a similar manner. 

Rubidium Niobates.—When niobium pentoxide is fused with rubidium carbonate and the melt is extracted with water, fine, silky needles of composition 3Rb20.4Nb205.9 Ha0 are left behind. Concentration of the filtrate yields monoclinic crystals of 4Rb20.3Nba0B. 14H20, which are isomorphous with the corresponding tantalum salt and with the corresponding caesium niobate and tantalate. a b c= 0-8815 1 1-0491 j3=95° 53. It slowly loses some of its water on exposure to- air.3... 

Rubidium Pemiobate, Rb3Nb08, is obtained as a white, crystalline powder by the action of rubidium carbonate and excess of hydrogen peroxide on 4 3 rubidium niobate. 

Rubidium Tantalate, 4Rb20.3Ta206.14H20, is obtained in transparent, colourless, monoclinic prisms by fusing tantalum pentoxide with rubidium carbonate and extracting the melt with water. It is isomorphous with the corresponding niobium salt and with 4 3 csesium tantalate. ... 

Rubidium Metarsenite, RbAs02, has been prepared8 by the action of arsenious oxide on rubidium carbonate in aqueous solution. It is a white amorphous powder which is converted to arsenate in aqueous solution and by the action of heat. The solution is alkaline in reaction. 

Rubidium Dihydrogen Orthoarsenate, RbH2As04, is obtained in the anhydrous form by fusing together equal parts of arsenious oxide and rubidium nitrate, or by neutralising rubidium carbonate solution with arsenic acid using methyl orange as indicator in the former method it yields tabular crystals and in the latter silky needles. At a dull red heat it forms the metarsenate. 

A solution of 1.5g of rubidium carbonate is neutralized with pure 57% hydriodic acid ( No. 89), avoiding an excess of acid. The solution is warmed to 60°C and 2.5g of pure iodine is dissolved in it by stirring. The mixture is allowed to cool and evaporated in the air to dryness. 

Two and one-half grams of rubidium chloride are dissolved in 7 ml water and 2,7g of iodine are suspended in the solution. If Hie chloride is not available it may be prepared by dissolving 2.4g of rubidium carbonate in the minimum of 6M hydrochloric acid and evaporating the neutral or slightly acid solution to dryness on the steam bath. 

The conversion of phenanthridine into an unspecified octahydro-derivative by hydrogenation over a sodium metal-rubidium carbonate catalyst has been reported.334 Hydrogenation of the tetrahydro-phenanthridine (231) over platinum in acetic acid gave, rather surprisingly, the octahydrophenanthridine (232) with loss of meth-oxyl.173... 

The same volume of solution is made using the same masses of two salts rubidium carbonate and calcium carbonate. Which salt gives the larger concentration of aqueous carbonate ions ... 

Rubidium hydride, RbH.—The hydride has been prepared 8 by a method analogous to that employed for sodium hydride. It can also be produced by heating rubidium carbonate with metallic magnesium in an... 

Rubidium iodide, Rbl.—The iodide is formed by the action of hydriodic acid on rubidium carbonate, and crystallizes in colourless... 

Rubidium thiosulphate, Rb2S203.—Interaction of rubidium carbonate and barium thiosulphate produces the dihydrate of rubidium thiosulphate.2 It is hygroscopic, and readily soluble in water. 

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