Hydrogen sulphates, hydrolysis

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. 

The analogous solidtliquid two-phase alkylation at the more acidic NH position of the diphenylphosphinic hydrazides (Table 5.27) proceeds smoothly in the presence of tetra-rt-butylammonium hydrogen sulphate [54], No reaction occurs under the standard liquiddiquid conditions. Hydrolysis of the A-alkylated phosphinic hydrazides in refluxing dilute hydrochloric acid provides a convenient and efficient route to A-alkylhydrazines [54], The reaction has been extended to the preparation of A. A -dialkylhydrazines from diphenylphosphinic hydrazide by acylation of the... 

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 hydrolysis of steroid hydrogen sulphates, important to biochemists in view of the excretion of many steroid hormone metabolites as water soluble salts of hydrogen sulphates, has been studied in some detail [20,21]. It had been known for some years that ether extraction of the steroid hydrogen sulphate from acidified solutions is accompanied by hydrolysis of the sulphate in the ether phase, with liberation of the steroid alcohol. This hydrolysis was shown to follow first-order kinetics, but to be dependent in a remarkable way on the solvent. Ethers are the most effective solvents, followed by others of low polarity including benzene, esters and ketones, while water and alcohols have a strong retarding effect on hydrolysis. Neither acids nor bases produce significant catalysis, and the presence of did not result in incorporation of isotopic... 

The preparation of phenols by hydrolysis of benzediazonium ions is well known in the literature (ref. 10). It involves the preparation of a diazonium salt, e.g. the diazonium hydrogenosulfate by treatment of the aniline hydrogen sulphate with sodium nitrite in dilute aqueous sulphuric acid, followed by hydrolysis in more concentrated aqueous sulphuric acid. The temperature of the hydrolysis is maintained at the boiling point of the aqueous acid by proper adjustment of the concentration of the sulphuric acid and the phenol formed removed from the reaction medium by means of steam distillation in order to minimise the coupling of the formed phenol with the diazonium salt introduced. 

The ionised carotenoid sulphate may be converted into the hydrogen sulphate by ion exchange. Hydrolysis of the sulphate may be accomplished enzymatically, or the sulphate group may alternatively be removed by acid hydrolysis [68]. 

Chromatographic properties of carotenoid sulphates are described in Vol. lA, Worked Example 11, which also describes chemical conversion into the free hydrogen sulphates by ion exchange and removal of sulphate groups by acid hydrolysis to provide the parent carotenol, as well as enzymic hydrolysis. 

Pressure increases up to 1 kbar decrease the acid-catalysed hydrolysis of esters in the presence of micelles of dodecyl hydrogen sulphate. Above this pressure the rate... 

Discussion. With an acidic titanium(IV) solution hydrogen peroxide produces a yellow colour with small amounts oftitanium(up to 0.5 mg ofTiOz permL), the intensity of the colour is proportional to the amount of the element present. Comparison is usually made with standard titanium(IV) sulphate solutions a method for their preparation from potassium titanyl oxalate is described below. The hydrogen peroxide solution should be about 3 percent strength (ten volume) and the final solution should contain sulphuric acid having a concentration from about 0.75 to 1.75M in order to prevent hydrolysis to a basic sulphate and to prevent condensation to metatitanic acid. The colour intensity increases slightly with rise of temperature hence the solutions to be compared should have the same temperature, preferably 20-25 °C. 

Moist diethyl sulphate was stored in an iron reservoir, which detonated after a little while. This accident was explained by the hydrolysis of the sulphate present that gives rise to the formation of sulphuric acid. By reacting with iron, sulphuric acid formed hydrogen that caused the overpressure responsible for the detonation. 

The mechanism of hydrolysis of 2-carboxyphenylsulphamic acid (42) might be expected to follow that for the hydrolysis of salicyl sulphate, but actually it is thought to proceed by classic intramolecular acid catalysis rather than by hydrogen-bond catalysis. Evidence for a substantial degree of proton transfer from the carboxyl group in the transition state has been obtained (Hopkins and Williams, 1982). 

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