Sulphuric acid, nitrosylous

Nitrosylsulphuric acid, and nitrosyl chloride formed as a result of chloride in the water, can cause corrosion in sulphuric acid and lead-chamber plants. Alloying is not generally beneficial in this instance and some elements (such as copper) can increase the corrosion rate. 

Very feebly basic amines cannot usually be diazotised in dilute acid media and in these instances the reaction has to be carried out in a concentrated acid, normally sulphuric acid. The usual technique is first to dissolve dry sodium nitrite in the concentrated acid, when reaction occurs in two stages (Scheme 4-8), resulting in the formation of nitrosylsulphuric acid (4.5). The nitrosyl ion - nitrous acid equilibrium has been evaluated spectroscopically. In 96% sulphuric acid the 15N-n.m.r. signal is characteristic of the free nitrosyl ion [4]. Reaction (2) of Scheme 4.8 is slow at room temperature and it is desirable to heat the mixture to 70 °C in order to attain equilibrium within a reasonable time. After cooling, the amine is added gradually and after a short time the reaction mixture is poured onto ice, giving an aqueous solution of the diazonium salt [20]. 

When the reaction is completed, add 20 ml of glacial acetic acid and rapidly transfer the reaction mixture onto a filter No. 2 for filtration in an inert atmosphere (see Fig. 64b). Separate the nitrosyl-sulphuric acid crystals in an atmosphere of dry nitrogen, wash them on a filter with glacial acetic acid cooled to 5 °C, rapidly transfer them to a preliminarily weighed watch glass and put them in a vacuum desiccator over phosphoric anhydride. Dry them for two or three hours. Write the equation of the reaction. Weigh the dry crystals and calculate the yield in per cent. 

Preparation of Nitrosyl Chloride by Reacting Nitrosyl-Sulphuric Acid with Sodium Chloride. Assemble an apparatus as shown in Fig. 89. Fill the system with dry nitrogen. Introduce into a flask... 

Formation.—When sulphur dioxide is passed into ice-cold fuming nitric acid, crystals of nitrosulphonic. acid separate.1 The acid is also obtained when sulphuric acid is treated with excess of nitrogen peroxide.2 It is also formed by the interaction of sulphur dioxide and nitrogen peroxide both in the absence or presence of water,8 and by the addition in equimolecular proportion of liquid nitrogen tetroxide to chloro-sulphonic acid in the absence of moisture.4 Sulphuric acid acts on either nitrous anhydride or nitrosyl chloride with formation of nitrosulphonic acid, according to the equations ... 

J. Biehringer and W. Borsum suggested that nitrosylsulphuric acid exists in two tautomeric forms, H0.S02.0. N0 + H0. S02.N02, which are in equilibrium in cone, sulphuric acid soln. and in the molten state. In support of this, they found that in some cases it can react simultaneously as two different acids, for, when a soln. of dimethylaniline in cone, sulphuric acid is slowly treated with the requisite amount of sodium nitrite, both p-nitrodimethylaniline and p-nitroso-dimethylaniline are produced, the former represents the nitrosyl-acid and the latter the nitroxyl-acid. At 10° to 15°, the yields are respectively 8-33 and 7+5... 

The alkenes are distinguished from the alkanes by their solubility in concentrated sulphuric acid and their characteristic reactions with dilute potassium permanganate solution and with bromine. Characterisation may be based upon the determination of their physical and/or spectral properties. Characterisation by way of solid adducts with nitrosyl chloride has been quite widely used in the terpene field the preparation of adducts with 2,4-dinitrobenzenesulphenyl chloride is described below (see also Section 8.1.1, p. 1128). 

Benzene activated with sulphuric acid would add on to N204 which, according to Battegay, has the structure of nitrosyl nitrate N02.0N0. An addition product was thought to be formed which, in the presence of an excess of sulphuric acid, would decompose to yield a nitro compound and nitrosylsulphuric acid. 

As a consequence of the strong oxidation processes occurring mostly during the trinitration (naturally at the expense of nitric acid) a relatively large quantity of nitrous acid is formed, which in sulphuric acid medium gives nitrosyl sulphuric acid ... 

The TNT in the washing tank is stirred, while hot, with nearly 70% sulphuric acid, to wash out nitrogen oxides and the rest of the HN03 or nitrosyl-sulphuric acid. Then it is sepaated from the acid and transferred to a sepaate, building for final washing. TNT, after it has been washed with sulphuric acid, contains 1-2% of HNOs and 1-2% of H2S04. 

Chloropicrin is a fairly stable compound. It is not hydrolysed by water and not attacked by mineral acids like hydrochloric, nitric and sulphuric, either cold or hot. Only 20% oleum decomposes it with formation of phosgene and nitrosyl sulphuric acid. ... 

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