Alkali fusion general

Constitution and Properties.—Quinin is one of the more powerful organic alkalies. It generally appears, whan pure, as an amorphous, resinous mass, of a dull whits color. Its formula is—CM Hw Na Ot -(- 6 aq. It may also be obtained in six-sided prismatic crystals, which ore a hydrate, containing six equivalents, or 10 5 per cent, of water, which are lost on fusion. 

Hydroxylation. The main general method for the hydroxylation of aromatic compounds is the alkali fusion of sulfonic acids ... 

Both the direct and the alcoholic alkali fusion methods gave recoveries of 90% or better with phenyl-containing silicones, the results obtained by the alcoholic alkali modification being generally higher. 

The quanitity of the raw material necessary to produce a reliable estimate of any element will depend on the selected detection instrument. In general, samples for uranium analysis are preconcentrated by evaporation, air-, freeze-, or oven-drying to remove water, and dry-ashing or wet-ashing to remove carbonaceous matter. For vegetation and soil, acid or alkali fusion followed by acid dissolution of the fusion cake is required to ensure dissolution of refractory materials. Aerosol, water, soft tissues, blood, and dry-ashed bone samples may be solubilized with mineral acids. 

This is 8-hydroxy-5,7-di-iodoquinoline. The easiest method of assay is by the flask-combustion technique, using about 12 mg, 1 ml 0-02N thiosulphate = 0-0006616 g C9H5ONI2. It can also be determined by the general alkali-fusion method for organically combined iodine given under Chiniofon Sodium using 0-1 g of sample, 1 ml 0-lN thiosulphate = 0-003308 g. The U.S.P. uses the method for Chiniofon after heating the assay sample first with 1 ml of 95 per cent ethanol and then 15 ml of sodium hydroxide solution until the ethanol has been expelled, 1 ml O-OSN silver nitrate 0-009924 g. 

Protection of the molten metals from air and moisture The protection of the molten metals has always been an essential point. Fusion under vacuum or an inert atmosphere (pure He or Ar, possibly gettered) is systematically used. In the past, also for small scale laboratory preparations, fusion under a protective layer of molten non-reactive salts was often used. Low density salt mixtures having low-melting point and high-boiling point were generally employed (for instance eutectic mixtures of anhydrous stable alkali halides). 

Quantitatively, sulfur in a free or combined state is generally determined by oxidizing it to a soluble sulfate, by fusion with an alkali carbonate if necessary, and precipitating it as insoluble barium sulfate. Oxidation can be effected with such agents as concentrated or fuming nitric acid, bromine, sodium peroxide, potassium nitrate, or potassium chlorate. Free sulfur is normally determined by solution in carbon disulfide, the latter being distilled from the extract. This method is not useful if the sample contains polymeric sulfur. 

Reaction LXXV. Fusion of Aromatic Sulphonic Acids with Caustic Alkalis. (Z. Ch (1876), 3, 299 J. pr., [2], 17, 394 20, 300.)—This method is of technical importance as it is employed to prepare phenols and naphthols from the parent hydrocarbons. These phenols and naphthols are much used as intermediates in the dye industry. The method cannot easily be applied to determine structure, owing to rearrangement liable to occur at the elevated temperatures. Caustic potash is more convenient than soda, since it generally yields a more easily fusible mixture. 

A fairly general procedure, which has also been used on the industrial scale, involves heating the alkali metal sulphonate with either sodium or potassium hydroxide in the presence of a small amount of water to aid the fusion process. The reaction mechanism may be formulated as a bimolecular nucleophilic addition-elimination sequence. 

The fusion of uranium oxides with alkali or alkaline earth carbonates, or thermal decomposition of salts of the uranyl acetate anion, gives orange or yellow materials generally referred to as uranates, for example,... 

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