Potassium nitridotrisulfate

The nitridotrisulfates are intermediate products in the preparation of sulfamic acid by the nitrite-hydrogen-sulfite reaction. The preparation of the potassium salt only is feasible, since it is but slightly soluble in water and therefore is not hydrolyzed as readily as the more soluble Sodium salt. The method outlined below is a modification of the procedure first proposed by Claus and Koch.  

Inorganic Syntheses, Volume II Edited by W Conard Femehus 11946 by McGraw-Hill Book Company, Inc. 

Potassium nitridotrisulfate crystallizes as the 2-hydrate in long brilliant needles. It is very slightly soluble in water and not appreciably soluble in liquid ammonia. In aqueous solutions it gives no precipitate with manganese-(II), mercury(II), silver, cadmium, cobalt(II), copper(II), or iron (II) ion but yields a white precipitate with lead acetate. Potassium nitridotrisulfate yields a precipitate with barium ion only in basic solution. 

Potassium nitridotrisulfate hydrolyzes slowly in neutral solution, and very rapidly in the presence of acid however, the solution may be stabilized by the addition of a base. If the compound is carefully purified, it may be kept in a desiccator for about a month before decomposition becomes appreciable. 

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Potassium nitridorhenate, 6 167 Potassium nitridotrisulfate, 2 182 Potassium nitrocarbamate, potassium salt, 1 68, 70 Potassium V-nitrosohydroxylamine-V-sulfonate, 5 117 by metathesis, 6 120 Potassium octacyanomolybdate(IV) 2-hydrate, 3 160 Potassium osmiamate, 6 204... 

Imidodisulfates can also be obtained by hydrolysis of nitridotrisulfates (see below). Figure 15.51 compares the structure of the imidodisulfate and parent disulfate ions, as determined from the potassium salts. Comparison with the hydroxyl-amine derivative K[HN(0H)S03] (below) is also instructive. 

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