Preparation of Hydroxylamine hydrochloride by reduction of nitrite, using sulfur dioxide
40g potassium nitrite (KNO2) and 50g potassium acetate (CH3COOK) are dissolved in 100ml ice water. 750g finely crushed ice is added. Into this
solution a stream of sulfur dioxide (SO2) is bubbled until the solution smells of SO2. The temperature must be kept below 0°C through the whole
reaction. The salt of K2[HON(SO3)2] separates and is filtered off and washed with ice water. The salt is dissolved in 500ml 0.5 M HCl and boiled for
two hours. Still boiling a solution of Barium chloride (BaCl2) is added as long as barium sulfate (BaSO4) precipitates ( CaCl2 may possibly work
instead). The BaSO4 is filtered off and the clear filtrate is evaporated to dryness. The residue consists of Potassium Chloride (KCl) and NH2OH*HCl.
Anhydrous ethanol(EtOH) is used for extraction of the Hydroxylammonium chloride, the KCl remains undissolved. The EtOH is evaporated on a water bath
and the product can be recrystallised from water (mp 151°C).
Mix cold saturated solutions containing one molecular proportion of sodium nitrate, and two molecular proportions of acid sodium sulphite, and then
adding a saturated solution of potassium chloride to the mixture. After standing for a day, hydroxylamine potassium disulphonate crystallizes out.
This is boiled for some hours with water and the solution cooled, when potassium sulphate separates first, and then hydroxylamine sulphate.
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