Hydroxylammonium sulphate

In this example are set forth the details of producing a full scale commercial batch of hydroxylammonium acid sulphate by the use of process according to the invention. There was charged to the reaction vessel 5300 pounds (50.3 moles) of 93% electrolytic grade sulphuric acid and 535 pounds (29.8 moles) of water which, with the water in the sulphuric acid, made a total of 906 pounds (50.4 mole). The mixture was heated to a temperature of from 135 to 140° C. and 5380 pounds (60.3 moles) of 1-nitropropane were added maintaining the temperature at from 135 to 140° C. This addition required a 7-1/2 hour period to complete. At the end of the addition period, the temperature was maintained at from 135 to 140° C. for an additional 1-1/2 hour holding period and then cooled to approximately 70° C. for separation of the layers. There were produced 6178 pounds of hydroxylammonium acid sulphate of a purity of 88.0% HAS. This was equivalent to 5420 pounds of hydroxylammonium acid sulphate on a 100% dry basis which represented a yield of 82.2% on the basis of the sulphuric acid charged. 

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Sulphuric acid is added to the electrolyte and the hydroxylamine is formed as hydroxylammonium sulphate, (NH30H)2S04 [cf, (NHJjSOj. Addition of barium chloride then precipitates barium sulphate and hydroxylammonium chloride, (NH30H)C1, is obtained. 

The special reducing agent (a solution containing cupro-ammonia ions) is first prepared. Dissolve 63 g. of crystallised copper sulphate in 250 ml. of water in a 1-Utre heaker, add 100 ml. of concentrated ammonium hydroxide solution (sp. gr. 0-88), and cool the solution to 10°. Dissolve 17 8 g. of hydroxylammonium chloride or 21 g. of hydroxylammonium sulphate in 60 ml. of water, cool to 10°, and add 42 -5 ml. of QN sodium hydroxide solution if the resulting solution of tydroxylamine is not clear, filter it at the pump. Without delay add the hydroxylamine solution, with stirring, to the ammoniacal cupric sulphate solution. Reduction occurs at once, a gas is evolved, and the solution assumes a pale blue colour. Protect the reducing agent from the air if it is not used immediately. 

Procedure. Prepare a manganese(II) sulphate solution (approx. 0.05M) by dissolving 11.15 g of the analytical-grade solid in 1 L of de-ionised water standardise the solution by titration with 0.05 M EDTA solution using solochrome black indicator after the addition of 0.25 g of hydroxylammonium chloride — see below. 

Discussion. This gravimetric determination depends upon the separation and weighing as elementary selenium or tellurium (or as tellurium dioxide). Alkali selenites and selenious acid are reduced in hydrochloric acid solution with sulphur dioxide, hydroxylammonium chloride, hydrazinium sulphate or hydrazine hydrate. Alkali selenates and selenic acid are not reduced by sulphur dioxide alone, but are readily reduced by a saturated solution of sulphur dioxide in concentrated hydrochloric acid. In working with selenium it must be remembered that appreciable amounts of the element may be lost on warming strong hydrochloric acid solutions of its compounds if dilute acid solutions (concentration <6M) are heated at temperatures below 100 °C the loss is negligible. 

Thus, copper and platinum give similar results the nitrite formation is greater with iron, nickel, and cobalt, and the nitrate formation less. The gases were mainly nitrous oxide and nitrogen with a small proportion of oxygen. N. D. Zelinsky and S. G. Krapiwin showed that the decomposition of hydroxylamine into acid and base does not occur in soln. with methyl alcohol as solvent. J. Tafel showed that an aq. soln. of hydroxylamine sulphate in presence of 20-50 per cent, of sulphuric acid is not reduced at a copper cathode. O. Flaschner observed some reduction in dil. sulphuric acid soln. J. Tafel and H. Hahl found that reduction always takes place when the sulphuric acid cone, in the layer of electrolyte in contact with the cathode is reduced beyond a certain point, and when there is no excess of acid in other words, when hydroxylamine sulphate itself is electrolyzed, the reduction is quantitative. These results are most readily accounted for on the view that only free hydroxylamine (produced in this case by partial hydrolysis of the sulphate), but not the hydroxylammonium ion, NH3OH, is reduced at a copper... 

In Example 1 the results of producing hydroxylammonium acid sulphate by the conventional process and by the process according to th< invention were compared. In the preparation by the conventional process, a mixture of 4.8 moles of 1-nitropropane and sufficient water tc-make a total of 4 moles with that present in the sulphuric acid wa.-prepared and heated to reflux. There was then added 4.0 moles oi sulphuric acid, either electrolytic grade, 93% or C.P. grade, 96%. Tin. addition was made very slowly over a 3 to 4-hour period and tlu refluxing of the completed mixture was continued for a total reaction time of 8 hours. The reaction mixture was then cooled to below ahoui 115° C. and the two layers separated. The lower layer oi hydroxylammonium acid sulphate layer was analysed for HAf (hydroxylammonium acid sulphate) content and its colour determincM on the Gardner 1933 Standard Colour Scale. The upper layer Oi propionic acid layer was analysed for total acidity which. was corrected for sulphuric acid and hydroxylammonium acid sulphate content ami the per cent, yield of propionic acid calculated therefrom. The results oi these experiments are set out in Table 1A below. 

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