Ammonium Perchlorate from K or Ba Perchlorate

Sometimes K, or or less commonly, Ba Perchlorate is available and can be used to make Ammonium Perchlorate.
The following came from Dave Faulkiner

Solubilities of alkali metal perchlorates at 25^oC

Salt	NaCLO₄	KCLO₄	NH₄CLO₄

Solvent	Solubility g/100g sol
Water	209.6	2.062	24.922
Methanol	51.36	0.105	6.862
Ethanol	14.71	0.012	1.907
Propanol	4.888	0.010	0.387
Acetone	51.745	0.155	2.260
Ethyl acetate	95.12	0.001	0.032
Ethyl ether	0.000	0.000	0.000

Making Ammonium Perchlorate

There are many different ways to make ammonium perchlorate (AP). They fall into two main categories:

Ion Exchange and

Double displacement reactions.

Ion Exchange is a method that incorporates exchanging a charged ion from another ion, for instance a sulphonated acidic resin would exchange K⁺ with H⁺ in potassium perchlorate to produce aqueous perchloric acid.

Double displacement reactions involve the exchange of ions within two compounds eg:

NaCLO₄ (aq) + KCL (aq) ® NaCl (aq) + KClO₄ (s), here we can see that the perchlorate ion, in the extremely soluble sodium perchlorate is displaced out of solution, due to its poor solubility with the potassium ion.

I have found that the most efficient double displacement reaction to use, to make AP is seen with equation (1):

2KClO₄ (aq) + (NH₄)₂SO₄ (aq) ® 2NH₄CLO₄ (aq) + K₂SO₄(aq) ………..(1)

Ba(ClO₄)₂ (aq) + (NH₄)₂SO₄ (aq) ® 2NH₄ClO₄ (aq) + BaSO₄ (aq)……………(2)

The first thing to observe is that 2 moles of potassium perchlorate and a 1 mol of a cheap fertiliser ammonium sulphate is used, to produce 2 mols of AP and 1 mol of potassium sulphate. The advantage of this reaction is that both products can be separated from each other in a clean and pure form.

Reaction 1:

Once both reactants are in solution heat both up to 80-90^oC and mix together while stirring, the displacement reaction is instantaneous under these conditions. Heat off most the water until a paste or sludge forms, both AP and PS are mixed into together, so the way to separate the two is by using a solvent where one component is soluble in and the other is insoluble. PS is insoluble in most alcohols, the best is ethanol, but because this solvent is extensive used in drug purification, regulations are placed on this alcohol. So the other alternative is methanol, usually 4X times the mass in volume is used to separate PS. The methanol can be evaporated away from the AP using low temperature distillation, this way most of the methanol used can be recovered and used for next time.

Reaction 2:

The advantage of this reaction is that barium sulphate is very insoluble in water and requires no final separation, however barium perchlorate is very expensive but can be prepared by making perchloric acid by ion exchange and reacting this with barium carbonate (which can be brought from a pottery place), according the equations below:

-SO₃H + K or NaClO₄ (aq) ® HClO₄ (aq)…..…………………………...….………(3)

2HClO₄ (aq) + Ba(CO₃)₂ (aq) ® Ba(ClO₄)₂(aq) + H₂O(l) + 2CO₂(g)……….........(4)

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