Melting with alkali

Preparation of Silicic Acid Anhydride. Dissolve a small amount of potassium silicate in a minimum amount of water, filter the solution if necessary, and add a 37 % hydrochloric acid solution up to a strongly acidic reaction. Transfer the solution into a porcelain bowl and evaporate it until dry in a sand bath. Wash the dry residue with warm water until the chloride ions are removed, then roast it and see how it reacts with solutions of an alkali and hydrofluoric acid in a lead bowl in a jum cupboard ). Write the equations of the reactions. What is obtained when silicic acid anhydride is melted with alkalies ... 

Beryllium chloride is prepared by passing CCLt over BeO at 800°C. On a small scale the pure chloride and bromide are best prepared by direct interaction in a hot tube. The white crystalline chloride (mp 405°C) dissolves exothermically in water from HC1 solutions the salt [Be(H20)4]Cl2 can be obtained. Beryllium chloride is readily soluble in oxygenated solvents such as ethers. In melts with alkali halides, chloroberyllate ions [BeCl4]2 may be formed, but this ion does not exist in aqueous solution. 

The free mercapto compounds (72) are extremely stable towards alkalis and acids, but they are quickly attacked by oxidizing agents.15,126 Disulfides (73) or disulfonic acids (74) are obtained, depending upon the conditions. On melting with alkali the latter compounds do not yield 2,6-dihydroxy derivatives but cleavage products. 

By application of strong oxidizing agents, c.g. by melting with alkali peroxides, Np and Pu can be transfonned into the oxidation state VII. 

Synthesis First synthesis in 1868 was technically not realizable in 1869 Graebe, Liebermann and Caro found an access to synthetic A. by sulfonation of an-thraquinone and subsequent melting with alkali after its market introduction iti 1871 the synthetic product quickly displaced the natural substance. 

For refractory powders, slags, minerals, and rocks, melting with alkali (NaCOs, K2CO3, Na2B407, etc.) or with acidic salts (K2S2O8, KHSO4, etc.) is very useful. 

Phenylpropanolamine. - With catalyst prepared as previously described from 0.5g of palladium chloride and 3g of charcoal, it was possible to reduce two portions of 9.8g of isonitrosopropio-phenone (0.06 mol), dissolved in 150 cc. of absolute alcohol containing 7. Og of hydrogen chloride, to phenylpropanolamine in from 145 - 190 minutes with yields of the isolated chloride from 9.4g to 11. Og, or 84 to 98% of the theoretical. After recrystallization from absolute alcohol the salt melted at 191°. The free base was obtained by treating an aqueous solution of the hydrochloride with alkali on cooling, the liberated amino alcohol solidified and after recrystallization from water melted at 103°."... 

It yields a phenylurethane melting at 41°, a semi-carbazone melting at 219° to 220°, and an oxime melting at 125°. The OH group appears to possess alcoholic as well as phenolic functions, forming acetic and benzoic esters, as well as direct combinations with alkalis. 

By heating carvacrol with alkalis, it is converted into isocuminic-acid, C(jH3(C3Hy)(OH)(COOH), melting at 93°. By oxidation with chromic acid mixture, thymoquinone results. This compound forms-crystalline tables melting at 45° to 46°. 

An isomeric compound, isoalantolactone, exists in the oil of Inula hdenium. It is a crystalline body melting at 115°, and yielding isoalantolic acid with alkalis, melting at 237° to 239°. 

To a solution of 20 parts of thiamine hydrochloride in 30 parts of water is added an aqueous solution of sodium hydroxide (7.2 parts of NaOH in 30 parts of water), and the mixture is cooled with water. The mixture is allowed to stand for 30 minutes, 60 parts of chloroform is added, followed by a solution of 30 parts of crude sodium tetrahydrofurfurylthiosulfate in 30 parts of water, and the whole is stirred for 30 minutes. The chloroform layer is separated and the aqueous layer is extracted twice with 20 parts of chloroform. All the chloroform solutions are combined and shaken with 50 parts of 5% hydrochloric acid. The acid solution is decolorized and neutralized with alkali carbonate, whereupon thiamine tetrahydrofurfuryl disulfide separates out in the resinous state but soon solidifies [MP 129 (decomp.)]. The yield is 16 parts. Recrystallization from ethyl acetate gives colorless prisms melting at 132°C (decomp.). 

Interaction between niobium oxide and fluorides, chlorides or carbonates of alkali metals in an ammonium hydrofluoride melt, yielded monooxyfluoroniobates with different compositions, MxNbOF3+x, where they were subsequently investigated [123-127]. According to DTA patterns of the Nb205 - 6NFL HF2 - 2MF system, (Fig. 18) a rich variety of endothermic effects result from the formation of ammonium monooxyfluoroniobate, its thermal decomposition and its interaction with alkali metal fluorides. The number of effects decreases and separation of ammonium ceases at lower temperatures and when going from lithium to cesium in the sequence of alkali metal fluorides. 

Tantalum powder is produced by reduction of potassium heptafluoro-tantalate, K2TaF7, dissolved in a molten mixture of alkali halides. The reduction is performed at high temperatures using molten sodium. The process and product performance are very sensitive to the melt composition. There is no doubt that effective process control and development of powders with improved properties require an understanding of the complex fluoride chemistry of the melts. For instance, it is very important to take into account that changes both in the concentration of potassium heptafluorotantalate and in the composition of the background melt (molten alkali halides) can initiate cardinal changes in the complex structure of the melt itself. 

Caesium azide melts with a little decomposition (<1%) at 598 K. There is slow decomposition of the solid when large amounts of NiO are present [714], Observations on the photolyses of RbN3 and CsN3 have been discussed [715] with reference to the pyrolyses of other alkali azides. 

For the preparation of monofluorophosphates there are quite a lot of methods found in literature. The alkali salts are obtained by shortly melting poly- or trimetaphosphate with alkali fluoride (29,30) - the application of graphite vessels yielding particulary pure products (31) ... 

Metal powders can readily react with alkali metal polychalcogenide melts at typical temperatures in the range 200 600°C to afford chalcogen-rich complexes. As discussed in an excellent review article,10 the highly ionic nature of the melt greatly enhances the solubility of the chosen metal and often facilitates the growth of single crystals. 

---