DE1113212B - Process for the production of solid, crystalline sodium-ammonium salt of Caro's acid - Google Patents

Description

The invention relates to the production of a new, previously unknown compound, namely the sodium ammonium salt of Caro's acid of the formula (NaNH ₄ ) (HSO ₅ ) ₂ in solid crystalline form. This salt has an active oxygen content of around 5.5 to 6.5% and forms white crystals. It can be stored in a cool and dry atmosphere and has a slight odor of ozone. 140 g dissolve in 100 ecm of water at room temperature. At 92 ° C the salt decomposes with elimination of oxygen. A 1% aqueous solution of ^e has a pH of 2.3.

It is known that the potassium salt of Caro's acid can be produced in solid form. Try other alkali or To obtain alkaline earth salts or the ammonium salt of Caro's acid in solid crystalline form, did not produce any results. Either smear occurs when such solutions evaporate, or the salts obtained are unstable.

Surprisingly, it has now been found that it is possible to use the sodium ammonium salt of Carose Obtain acid in solid crystalline and quite stable form. An aqueous solution is added to this Caro's acid or a salt of Caro's acid mixed with sulfuric acid with ammonia, Ammonium bicarbonate or ammonium carbonate and with caustic soda, sodium bicarbonate or sodium carbonate. The resulting solution is then, if appropriate after separating off, the precipitated in solid form Sulphates and bisulphates, evaporated to dryness at low temperature.

Instead of a solution of Caro's acid or its salts, a mixture of oleum can also be used use with hydrogen peroxide, ammonium persulphate or sodium persulphate.

The reaction is expediently carried out at a temperature of 20 to 70.degree. At higher temperatures there is a risk of decomposition.

The evaporation is advantageously carried out at a temperature of up to 55 ° C., with a reduced temperature Applying pressure. This measure also serves to increase the yield and to reduce the Decomposition losses.

The best way to proceed is to first mix the oleum with the hydrogen peroxide, the ammonium persulphate or the sodium persulphate and only then the alkaline ammonium and sodium compounds clogs. The substances used can be in the form of their aqueous solutions, preferably their concentrated solutions.

The reaction mixture is expediently before the addition of the alkaline ammonium and

crystalline sodium ammonium salt

Caro's acid

Applicant:
German gold and silver separator

formerly Roessler,
Frankfurt / M., Weißf rauenstr. 9

Dr. Franz Beer and Dr. Josef Müller,

Rheinfelden (Bad.),
have been named as inventors

Sodium compounds diluted with water, advantageously with so much that up to 3 parts by weight of water are present _{for 1 part by weight of total SO 3.}

In order to obtain a salt of the desired composition, it is appropriate to add 0.3 to 1 mole of ammonia to 1.6 moles, preferably 0.4 to 1.4 moles, of sodium to be used.

The total addition of the alkaline ammonium and sodium compounds should be calculated so that For 1 mole of bisulfate, 0.8 to 4 moles, preferably 1 to 3 moles, of neutral sulfate are formed.

example 1

25% strength oleum ^it with a total of 3.01 moles of SO ₃ are mixed as a 92 weight percent aqueous solution under cooling at 30 to 40 ⁰ C with 2.15 mol H ₂ O _2. It is then diluted to 11 with cold water, 92.5% of the hydrogen peroxide used being converted into Caro's acid. Then added a 10% aqueous solution of ^e 1.962 moles of ammonia and a saturated sodium carbonate solution with 0.981 mol to. The yield in the neutralization amounts to 95% · The resulting solution is evaporated to 6O ⁰ C in vacuum at 50th The resulting dry salt contains 6.48% active oxygen.

Example 2

25 ° / _o oleum with 3.11 moles of total SO ₃ are added while cooling from 30 to 4O ⁰ C with 2.21 mole of H ₂ O ₂ as a 92 weight percent solution. The mixture

109 680/215

10

is diluted to 11 with cold water. This solution contains 91.6% of the active oxygen used as Caro's acid. Then 1.546 mol of NaOH as a 35% strength aqueous solution and 1.546 mol of NH ₃ as a 10% strength aqueous solution are added. Finally, 1.283 moles of ammonium sulfate are added. The neutralization yield is 96.3%. Evaporation in vacuo at 50 to 60 ⁰ C with a dry, tough salt with 5.1% active oxygen is obtained.

Example 3

0.7 mol of SO ₃ in the form of 25% oleum are mixed at 40 ° C. with 0.5 mol of ammonium persulfate and 0.5 mol of H ₂ O ₂ in the form of a 70 percent strength by weight aqueous solution. After briefly heating to 60 ° C., it is diluted to 490 ecm with water. 90.4% of the active oxygen is then in the form of Caro's acid. It is neutralized with a dilute aqueous solution of 0.164 mol of ammonia and a saturated aqueous solution of 0.5265 mol of sodium carbonate. The yield on neutralization is almost quantitative. After evaporation of the solution under vacuum at 50 to 6O ⁰ C is obtained a dry, tough salt with 5.95% active oxygen.

Example 4

0.7 mol of SO ₃ in the form of 25% oleum are mixed at 40 ° C. with 0.5 mol of ammonium persulfate and 0.5 mol of H ₂ O ₂ in the form of a 70% by weight solution. After brief heating to 60 ° C., the mixture is diluted to 500 ecm while cooling with water. 90.5% of the active oxygen is converted into Caro's acid. It is then neutralized with a saturated aqueous solution of 0.6178 mol of sodium bicarbonate. When the solution is evaporated in vacuo at 50 to 60 ° C., a dry, durable salt with 5.9% active oxygen is obtained.

Claims (9)

PATENT CLAIMS: 1. A process for the preparation of solid, crystalline sodium ammonium salt of Caro's acid in a mixture with sodium and ammonium sulfate and bisulfate, characterized in that a mixture of Caro's acid and sulfuric acid with ammonia, ammonium bicarbonate or ammonium carbonate and with caustic soda, Sodium bicarbonate or sodium carbonate are added and the resulting solution is then evaporated to dryness at a low temperature, if appropriate after separating the sulfates and bisulfates which have separated off. 2. The method according to claim 1, characterized in that instead of a mixture of Caro's acid with sulfuric acid a mixture of oleum with hydrogen peroxide, ammonium persulfate or sodium persulfate is used. 3. The method of claim 1 or 2, characterized in that is allowed to take place at a temperature of 20 to 70 ⁰ C the reaction. 4. The method according to any one of claims 1 to 3, characterized in that the evaporation of the solution is carried out below about 55 ⁰ C at reduced pressure. 5. The method according to any one of claims 1 to 4, characterized in that first the oleum combines with hydrogen peroxide, ammonium persulphate or sodium persulphate and then adding the alkaline ammonium and sodium compounds. 6. The method according to claim 5, characterized in that the mixture of the oleum with the hydrogen peroxide, the ammonium persulfate or the sodium persulfate is diluted with water before the addition of the alkaline ammonium and sodium compounds, advantageously with such amounts that to 1 part by weight of total SO ₃ to 3 parts by weight of water are present. 7. The method according to any one of claims 1 to 6, characterized in that the hydrogen peroxide, the ammonium persulphate, the sodium persuÖat and the alkaline ammonium and Sodium compounds are used in the form of aqueous, preferably concentrated, solutions. 8. The method according to any one of claims 1 to 7, characterized in that there is 1 mol of ammonia 0.3 to 1.6 moles, preferably 0.4 to 1.4 moles, of sodium are used. 9. The method according to any one of claims 1 to 8, characterized in that there is so much alkaline Ammonium and sodium compounds add 0.8 to 4 mol, preferably to 1 mol of bisulfate 1 to 3 moles of neutral sulfate are formed. © 109 680/215 8.61