Potassium isolation

In 1789 M. H. Klaproth examined pitchblende, thought at the time to be a mixed oxide ore of zinc, iron and tungsten, and showed that it contained a new element which he named uranium after the recendy discovered planet, Uranus. Then in 1828 J. J. Berzelius obtained an oxide, from a Norwegian ore now known as thorite he named this thoria after the Scandinavian god of war and, by reduction of its tetrachloride with potassium, isolated the metal thorium. The same method was subsequendy used in 1841 by B. Peligot to effect the first preparation of metallic uranium. 

Photoaffinity labeling (Nakayama et al, 1991 Hatanaka et al, 1994a,b, 1996 Kotzyba-Hilbert et al, 1995 Hashimoto et al, 1997, 2001 Curry et al, 1998 Koumanov et al, 1998 Fishkin et al, 2000 Matsubayashi et al, 2000) probes based on potassium isoles-pedezate (13) have been developed to explore the target protein for 13, the leaf-opening... 

Fluorine cannot be prepared directly by chemical methods. It is prepared in the laboratory and on an industrial scale by electrolysis. Two methods are employed (a) using fused potassium hydrogen-fluoride, KHFj, ill a cell heated electrically to 520-570 K or (b) using fused electrolyte, of composition KF HF = 1 2, in a cell at 340-370 K which can be electrically or steam heated. Moissan, who first isolated fluorine in 1886, used a method very similar to (b) and it is this process which is commonly used in the laboratory and on an industrial scale today. There have been many cell designs but the cell is usually made from steel, or a copper-nickel alloy ( Monel metal). Steel or copper cathodes and specially made amorphous carbon anodes (to minimise attack by fluorine) are used. Hydrogen is formed at the cathode and fluorine at the anode, and the hydrogen fluoride content of the fused electrolyte is maintained by passing in... 

Pure ethyl hydrogen sulphate is difficult to prepare, as it is an oily liquid, very soluble in water, and easily hydrolysed. It is therefore usually isolated as the potassium salt, since potassium ethyl sulphate crystallises well from water, and is not readily hydrolysed in neutral or weakly alkaline solution. 

Hexamethylene glycol, HO(CH2)gOH. Use 60 g. of sodium, 81 g. of diethyl adipate (Sections 111,99 and III,100) and 600 ml. of super-d ethyl alcohol. All other experimental detaUs, including amounts of water, hydrochloric acid and potassium carbonate, are identical with those for Telramelhylene Glycol. The yield of hexamethylene glycol, b.p. 146-149°/ 7 mm., is 30 g. The glycol may also be isolated by continuous extraction with ether or benzene. 

Vigorous oxidation of a monosaccharide (e.g., with dUute nitric acid) produces carboxyl groups at both ends of the chain. Thus galactose gives the sparingly soluble mucic acid glucose affords the soluble saccharic acid, which is best isolated as the sparingly soluble acid potassium salt. 

Saccharic acid. Use the filtrate A) from the above oxidation of lactose or, alternatively, employ the product obtained by evaporating 10 g. of glucose with 100 ml. of nitric acid, sp. gr. 1 15, until a syrupy residue remains and then dissolving in 30 ml. of water. Exactly neutralise at the boiling point with a concentrated solution of potassium carbonate, acidify with acetic acid, and concentrate again to a thick syrup. Upon the addition of 50 per cent, acetic acid, acid potassium saccharate sepa rates out. Filter at the pump and recrystaUise from a small quantity of hot water to remove the attendant oxahc acid. It is necessary to isolate the saccharic acid as the acid potassium salt since the acid is very soluble in water. The purity may be confirmed by conversion into the silver salt (Section 111,103) and determination of the silver content by ignition. 

An alternative method of removing the aniline is to add 30 ml. of concentrated sulphuric acid carefully to the steam distillate, cool the solution to 0-5°, and add a concentrated solution of sodium nitrite until a drop of the reaction mixture colours potassium iodide - starch paper a deep blue instantly. As the diazotisation approaches completion, the reaction becomes slow it will therefore be necessary to teat for excess of nitrous acid after an interval of 5 minutes, stirring all the whUe. About 12 g. of sodium nitrite are usually required. The diazotised solution is then heated on a boiling water bath for an hour (or until active evolution of nitrogen ceases), treated with a solution of 60 g. of sodium hydroxide in 200 ml. of water, the mixture steam-distilled, and the quinoline isolated from the distillate by extrsM-tion with ether as above. 

Saponification of esters. Aqueous sodium hydroxide method. To hydrolyse an ester of an alcohol, reflux 5-6 g. with 50 ml. of 20 per cent, sodium hydroxide solution for 1-2 hours or until the ester layer disappears. Distil the alkahne mixture and collect about 6 ml. of distillate. This will contain any volatile alcohol formed in the saponification. If the alcohol does not separate, i.e., is water-soluble, saturate the distillate with sohd potassium carbonate an upper layer of alcohol is then usually formed. (The alcohol may be subsequently identified as the 3 5-dinitrobenzoate see Section 111,27,2.) Cool the residual alkahne mixture, and acidify it with dilute sulphuric acid. If no crystalline acid is precipitated, the acid may frequently be isolated by ether extraction, or it may be distilled from the acidified solution and isolated from (or investigated in) the distfllate. (The acid may be subsequently identified, e.g., as the S benzyl wo-thiuronium salt see Section 111,85,2.)... 

Hydrolysis of a sulphonamide. Mix 2 g. of the sulphonamide with 3-5 ml. of 80 per cent, sulphuric acid in a test-tube and place a thermometer in the mixture. Heat the test-tube, with frequent stirring by means of the thermometer, at 155-165° until the solid passes into solution (2-5 minutes). Allow the acid solution to cool and pour it into 25-30 ml. of water. Render the resulting solution alkaline with 20 per cent, sodium hydroxide solution in order to liberate the free amine. Two methods may be used for isolating the base. If the amine is volatile in steam, distil the alkaline solution and collect about 20 ml. of distillate extract the amine with ether, dry the ethereal solution with anhydrous potassium carbonate and distil off the solvent. If the amine is not appreciably steam-volatile, extract it from the alkaline solution with ether. The sulphonic acid (as sodium salt) in the residual solution may be identified as detailed under 13. 

Gr. beryllos, beryl also called Glucinium or Glucinum, Gr. glykys, sweet) Discovered as the oxide by Vauquelin in beryl and in emeralds in 1798. The metal was isolated in 1828 by Wohler and by Bussy independently by the action of potassium on beryllium chloride. 

Ultrapure iodine can be obtained from the reaction of potassium iodide with copper sulfate. Several other methods of isolating the element are known. 

The metal apparently was first isolated in 1841 by Peligot, who reduced the anhydrous chloride with potassium. 

After 5 hours the reaction is stopped and the flask cooled. The formyl-MDA can be isolated and hydrolyzed by any of the ways Strike just mentioned a few paragraphs back, but this method offers a third, very convenient way which should be tried. What the chemist does is forget about letting the flask and its contents cool. Instead, she removes the oil bath, places the flask back on the stirplate (distillation setup still attached), attaches a vacuum and distills off all the formamide. What remains is a dark, heavy formyl-MDA precipitate that is allowed to cool down while the chemist makes up a solution of 150g potassium hydroxide (KOH), 500mL ethanol and 125mL dH20. This solution is poured into the... 

In this preparation, phenyi-2-nitropropene is reduced to phenyl-2-nitropropane with sodium borohydride in methanol, followed by hydrolysis of the nitro group with hydrogen peroxide and potassium carbonate, a variety of the Nef reaction. The preparation is a one-pot synthesis, without isolation of the intermediate. 

Note 3. This compound is commercially available as a 55% aqueous solution. It can be isolated by saturating the solution with anhydrous potassium carbonate The upper layer is dried over a small amount of potassium carbonate and subsequently distilled b.p. 40 C/35 mmHg. 

The ketone is added to a large excess of a strong base at low temperature, usually LDA in THF at -78 °C. The more acidic and less sterically hindered proton is removed in a kineti-cally controlled reaction. The equilibrium with a thermodynamically more stable enolate (generally the one which is more stabilized by substituents) is only reached very slowly (H.O. House, 1977), and the kinetic enolates may be trapped and isolated as silyl enol ethers (J.K. Rasmussen, 1977 H.O. House, 1969). If, on the other hand, a weak acid is added to the solution, e.g. an excess of the non-ionized ketone or a non-nucleophilic alcohol such as cert-butanol, then the tautomeric enolate is preferentially formed (stabilized mostly by hyperconjugation effects). The rate of approach to equilibrium is particularly slow with lithium as the counterion and much faster with potassium or sodium. 

The amino add analysis of all peptide chains on the resins indicated a ratio of Pro Val 6.6 6.0 (calcd. 6 6). The peptides were then cleaved from the resin with 30% HBr in acetic acid and chromatogra phed on sephadex LH-20 in 0.001 M HCl. 335 mg dodecapeptide was isolated. Hydrolysis followed by quantitative amino acid analysis gave a ratio of Pro Val - 6.0 5.6 (calcd. 6 6). Cycll2ation in DMF with Woodward s reagent K (see scheme below) yielded after purification 138 mg of needles of the desired cyc-lododecapeptide with one equiv of acetic add. The compound yielded a yellow adduct with potassium picrate, and here an analytically more acceptable ratio Pro Val of 1.03 1.00 (calcd. 1 1) was found. The mass spectrum contained a molecular ion peak. No other spectral measurements (lack of ORD, NMR) have been reported. For a thirty-six step synthesis in which each step may cause side-reaaions the characterization of the final product should, of course, be more elaborate. 

Cyanides. Salts of the complex ion, [Au(CN)2] , can be formed directiy from gold, ie, gold dissolves ia dilute solutions of potassium cyanide ia the presence of air. Additionally, a gold anode dissolves ia a solution of potassium cyanide. The potassium salt can be isolated by evaporation of the solution and purified by recrystallization from water (177). Boiling of the complex cyanide ia hydrochloric acid results ia formation of AuCN [506-65-01]. Halogens add oxidatively to [Au(CN)2] to yield salts of [Au(CN)2X2] which are converted to the tetracyanoaurates usiag excess cyanide (178). These last can also be prepared directiy from the tetrahaloaurates. 

A number of chemiluminescent reactions may proceed through unstable dioxetane intermediates (12,43). For example, the classical chemiluminescent reactions of lophine [484-47-9] (18), lucigenin [2315-97-7] (20), and transannular peroxide decomposition. Classical chemiluminescence from lophine (18), where R = CgH, is derived from its reaction with oxygen in aqueous alkaline dimethyl sulfoxide or by reaction with hydrogen peroxide and a cooxidant such as sodium hypochlorite or potassium ferricyanide (44). The hydroperoxide (19) has been isolated and independentiy emits light in basic ethanol (45). 

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