Potassium hydrogen sulphate

CH2 CH CH0. a colourless, volatile liquid, with characteristic odour. The vapour is poisonous, and intensely irritating to eyes and nose b.p. 53"C. It is prepared by the distillation of a mixture of glycerin, potassium sulphate and potassium hydrogen sulphate. It is manufactured by direct oxidation of propene or cross-condensation of ethanal with meth-anal. 

CHjCOCOOH. A colourless liquid with an odour resembling that of ethanoic acid, m.p. 13 C, b.p. 65 C/lOmm. It is an intermediate in the breakdown of sugars to alcohol by yeast. Prepared by distilling tartaric acid with potassium hydrogen sulphate. Tends 10 polymerize to a solid (m.p. 92 C). Oxidized to oxalic acid or ethanoic acid. Reduced to ( + )-Iactic acid. 

Hydrolysis of Potassium Ethyl Sulphate. Dissolve about i g. of the crystals in about 4 ml. of cold distilled water, and divide the solution into two portions, a) To one portion, add barium chloride solution. If pure potassium ethyl sulphate were used, no precipitate should now form, as barium ethyl sulphate is soluble in water. Actually however, almost all samples of potassium ethyl sulphate contain traces of potassium hydrogen sulphate formed by slight hydrolysis of the ethyl compound during the evaporation of its solution, and barium chloride almost invariably gives a faint precipitate of barium sulphate. b) To the second portion, add 2-3 drops of concentrated hydrochloric acid, and boil the mixture gently for about one minute. Cool, add distilled water if necessary until the solution has its former volume, and then add barium chloride as before. A markedly heavier precipitate of barium sulphate separates. The hydrolysis of the potassium ethyl sulphate is hastened considerably by the presence of the free acid Caustic alkalis have a similar, but not quite so rapid an effect. 

SO, + 2H,0 + Br, — HjSO, + 2HBr Alternatively, the acid mixture may be obtained from the reaction between potassium bromide solution and concentrated sulphuric acid below 76° the potassium hydrogen sulphate crystallises out and is removed by filtration ... 

It may be pointed out that dehydration of p hydroxy esters with fused potassium hydrogen sulphate, acetic anhydride, phosphoric oxide or with tliionyl chloride in benzeue solution leads to ap unsiiturated esters containing some PY-unsaturated ester the proportion of the latter depends not only upon the structure of the ester but also upon the dehydrating agent used. Elehydration occasionally occurs during the reaction itself or upon attempted distillation. 

The next step was to convert the synthetic terpineol into dipentene, which was readily accomplished by heating with potassium hydrogen sulphate, when water was eliminated and dipentene formed—... 

Diphenyl sulphoxide was obtained when a solution of diphenyl sulphide was treated with potassium hydrogen sulphate in ethanol and acetic acid131. 

E 515 Potassium sulphates (i) Potassium sulphate (ii) Potassium hydrogen sulphate... 

Under suitable conditions, certain chemical reactions will give rise to nacreous sulphur the most satisfactory result is obtained by allowing slow inter-diffusion of solutions of sodium thiosulphate and potassium hydrogen sulphate to occur.7 Another method involves the gradual decomposition of sulphur chloride or bromide by the vapour of water or methyl alcohol at the ordinary temperature.8 The decomposition of calcium polysulphidcs by hydrochloric acid,9 and of hydrogen persulphide by the addition of alcohol, ether, ethyl acetate or other organic solvents, also yields sulphur of the desired modification. 

In addition to potassium hydrogen sulphate and sodium hydrogen sulphate8 for opening up the ore, potassium carbonate,9 sodium peroxide, and alkali hydroxides 10 have been employed. The use of potassium hydroxide is preferred in the case of a high-grade ore of low titanium content 11 it has the advantage over sodium hydroxide that potassium tantalates are soluble in solutions which contain excess of the alkali, whereas sodium tantalates are insoluble. 

The analysis of ferrotantalum alloys and of tantalum steels also involves the conversion of the tantalum present into the pentoxide. The material is dissolved in hydrofluoric add and nitric acid, evaporated to dryness, and the residue fused with potassium hydrogen sulphate extraction with dilute hydrochloric acid and hydrolysis yield a predpitate of hydrated tantalic pentoxide, the iron remaining in solution.7... 

The detection of niobium and tantaluA ideg nfli almost entirely on the reactions given by niobic acid and tanxanc acid. All the common niobium and tantalum compounds are hydrolysed on bdng boiled in acid solutions, and yield precipitates of the respective adds. Natural minerals are previously fused with potassium hydrogen sulphate, and the aqueous extract of the melt usually precipitates the mixed acids... 

After being strongly ignited, niobium pentoxide becomes insoluble in all acids other than hydrofluoric acid, but is dissolved by molten potassium hydrogen sulphate, ammonium hydrogen sulphate, and borax. It is also insoluble in solutions of alkalis, but is converted into the alkali niobates by fusion with alkali hydroxides and carbonates. 

Platinum alloys containing from 0 5 to 20 per cent, of tantalum are hard, withstand heat, as well as the action of adds and fused potassium hydrogen sulphate, and are more resistant to the action of aqua-regia than platinum.8 They possess the mechanical properties off platinum-iridium alloys and are less expensive the relative quantities, of tantalum and iridium required to produce the same hardness and mechanical resistance are stated to be 1 5. Platinum-tantalum alloys, hence have been recommended for various purposes in place of platinum or platinum-iridium. Tantalum can also be coated with platinum, andl can then be utilised in high-temperature work. ... 

Hydrates of Tantalum Pentoxide, Colloidal Tantalum Pentoxide, Tantalic Acid.—When tantalum pentachloride or pentabromide is treated with water, or when a solution of a tantalate is boiled with dilute acids, a gelatinous predpitate of more or less hydrated tantalum pentoxide is thrown down. Insoluble tantalates on fusion with potassium hydrogen sulphate and extraction of the melt with water give the gel. In dealing with double fluorides of tantalum it is necessary to remove all the hydrofluoric add by evaporation with concentrated sulphuric acid, otherwise double fluorides are obtained. 

Sulphates.—No sulphates of tantalum have been definitely prepared. A fused mass of tantalum pentoxide and potassium hydrogen sulphate after extraction with boiling water is crystalline and contains the sulphate radical, and it has been assumed that a sulphate of tantalum is present. After drying at 100° C. the product in one case 1 had the composition 3Ta205.S08.9H20, but this was most probably the hydrolytic decomposition product of an unstable sulphate present in the melt or in solution.2... 

Many other methods of preparation have been employed. For example, the triiodide is formed when arsenious oxide,5 or a mixture of this oxide with sulphur,6 is heated in iodine vapour or when arsenious oxide is heated with iodine,7 hydriodic acid,8 a mixture of potassium iodide and acetic acid,9 or a mixture of potassium iodide and potassium hydrogen sulphate.10 When arsenic disulphide and iodine, in the proportions 1 As Ss 3la, are heated together, arsenic triiodide is formed.11 When arsenic trisulphide is fused with an excess of iodine, the product is soluble in carbon disulphide and the solution on evaporation deposits arsenic triiodide, then a sulphiodide and finally sulphur with excess of sulphide the product is the sulphiodide, AsS2I. If a solution of iodine in carbon disulphide is added to arsenic di- or tri-sulphide, the triiodide and sulphur are formed. The triiodide is also produced when a mixture of the trisulphide and mercuric iodide is heated 12. when hydriodic... 

This dehydration proceeds under acidic conditions and is a widely used olefin-forming reaction. In the laboratory phosphoric acid is the reagent of choice sulphuric acid, which is often used, can lead to extensive charring and oxidation and hence to lower yields of alkene. Other reagents include potassium hydrogen sulphate and anhydrous copper(n) sulphate.17 Passage over heated alumina is also effective. 

The success of the reaction is crucially dependent on the cleanliness of the zinc surface, prior to the formation of the organozinc reagent sonication has been suggested as a valuable aid to this reaction (cf. Expt 7.14). Under standard conditions, the hydroxy ester is the major product when the reaction is carried out in ether or benzene the contaminants which frequently arise during distillation are the a,0- and 0,y-unsaturated esters. Dehydration can be deliberately effected with the aid of reagents such as fused potassium hydrogen sulphate or acetic anhydride. Catalytic hydrogenation of the mixture of unsaturated esters fol-... 

Procedure for BOC-amino acids. A solution of the amino acid (10 mol) in a mixture of dioxane (20 ml), water (10 ml) and 1 m sodium hydroxide (10 ml) is stirred and cooled in an ice-water bath. Di-t-butyl pyrocarbonate (1) (2.4 g, 11 mmol) is added and stirring is continued at room temperature for 30 minutes. The solution is concentrated in vacuo to about 10-15 ml, cooled in an ice-water bath, covered with a layer of ethyl acetate (30 ml) and acidified with dilute aqueous potassium hydrogen sulphate solution to pH 2-3 (Congo red). The aqueous phase is extracted with ethyl acetate (2 x 15 ml). The ethyl acetate extracts are pooled, washed with water (2 x 30 ml), dried over anhydrous sodium sulphate and evaporated in vacuo. The residue is recrystallised with a suitable solvent (e.g. ethyl acetate-hexane). 

Polyhydric alcohols are colourless viscous liquids, or crystalline solids. Upon heating with a little potassium hydrogen sulphate, they may yield aldehydes (e.g. ethylene glycol yields acetaldehyde glycerol gives the irritating odour of acrolein which can additionally be detected with Schiffs reagent). Two confirmatory tests for polyhydric alcohols are as follows. 

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