US3915733A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of Berlin blue
Assignee: Evonik Operations GmbH
•
Filing: 1974-02-01
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Granted: 1975-10-28
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Expires: 1994-02-01
Abstract
Abstract Berlin blue is produced by converting (a) calcium ferrocyanide, sodium ferrocyanide or magnesium ferrocyanide with (b) an iron II salt at a pH below 7 to an acidic iron II salt of ferrocyanic acid FeH2(Fe(CN)6). The calcium or sodium ions can be washed out of the precipitate of the ferrocyanic salt. The precipitate is treated with (c) an inorganic or organic potassium salt to form Berlin white and then oxidized to Berlin blue. Alternatively, (a), (b) and (c) can be reacted together at a temperature of 20* to 60*C. to form Berlin white directly.
Inventors
- 👤 Helmut Reinhardt
- 👤 Karl Trebinger
- 👤 Gottfried Kallrath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:24
CPC Classifications
C; C01; C01C; C01C3/00; C01C3/08; C01C3/12; C09; C09C; C09C1/00; C09C1/22; C09C1/26; C01P; C01P2006/00; C01P2006/60
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
108 words
A PROCESS COMPRISING REACTING IN WATER (A) A MEMBER OF THE GROUP CONSSTING OF CALCIUM FERROCYANIDE, SODIUM FERROCYANIDE AND MAGNESIUM FERROCYANIDE WITH (B) A WATER SOLUBLE IRON II SALT WHICH DOES NOT FORM A WATER INSOLUBLE SALT WITH CALCIUM, MAGNESIUM OR SODIUM AND (C) WITH A WATER SOLUBLE POTASSIUM SALT AT A PH BELOW 7 TO FORM BERLIN WHITE, SAID PROCESS BEING CARRIED OUT IN TWO STEPS IN WHICH THE FERROCYANIDE AND THE IRON II SALT FIRST ARE REACTED TO FORM AN ACIDIC FERROCYCANIC ACID SALT OF THE FORMULA FEH2$FE(CN6)$AS A PRECIPITATE AND THEN THE PRECIPITATE IS TREATED WITH A WATER SOLUBLE POTASSIUM SALT TO FORM BERLIN WHITE.
Claim 2
Dependent Claim
108 words
A PROCESS COMPRISING REACTING IN WATER (A) A MEMBER OF THE GROUP CONSSTING OF CALCIUM FERROCYANIDE, SODIUM FERROCYANIDE AND MAGNESIUM FERROCYANIDE WITH (B) A WATER SOLUBLE IRON II SALT WHICH DOES NOT FORM A WATER INSOLUBLE SALT WITH CALCIUM, MAGNESIUM OR SODIUM AND (C) WITH A WATER SOLUBLE POTASSIUM SALT AT A PH BELOW 7 TO FORM BERLIN WHITE, SAID PROCESS BEING CARRIED OUT IN TWO STEPS IN WHICH THE FERROCYANIDE AND THE IRON II SALT FIRST ARE REACTED TO FORM AN ACIDIC FERROCYCANIC ACID SALT OF THE FORMULA FEH2$FE(CN6)$AS A PRECIPITATE AND THEN THE PRECIPITATE IS TREATED WITH A WATER SOLUBLE POTASSIUM SALT TO FORM BERLIN WHITE.
Claim 3
Dependent Claim
17 words
A process according to claim 1 wherein about equivalent amounts of (a), (b) and (c) are employed.
Claim 4
Dependent Claim
74 words
A process according to claim 1 comprising reacting in water a member of the group consisting of calcium ferrocyanide and sodium ferrocyanide with a water soluble iron II salt which does not form a water insoluble salt with calcium or sodium at a pH below 7 to form an acidic ferrocyanic acid salt of the formula FeH2(Fe(CN)6) as a precipitate and treating the precipitate with a water soluble potassium salt to form Berlin white.
Claim 5
Dependent Claim
23 words
A process according to claim 3 including the step of oxidizing the Berlin white to Berlin blue by adding an oxidizing agent thereto.
Claim 6
Dependent Claim
13 words
A process according to claim 4 comprising washing the ferrocyanic acid with water.
Claim 7
Dependent Claim
22 words
A process according to claim 4 wherein the oxidizing agent is an alkali metal chlorate, an alkali metal chromate or hydrogen peroxide.
Claim 8
Dependent Claim
17 words
A process according to claim 4 wherein the potassium salt is a salt of an inorganic acid.
Claim 9
Dependent Claim
16 words
A process according to claim 4 wherein the potassium salt is potassium chloride or potassium sulfate.
Claim 10
Dependent Claim
17 words
A process according to claim 7 wherein the potassium salt is a salt of an organic acid.
Claim 11
Dependent Claim
16 words
A process according to claim 9 wherein the potassium salt is potassium acetate or potassium citrate.
Claim 12
Dependent Claim
23 words
A process according to claim 4 wherein the water soluble iron salt is iron II chloride, iron II bromide or iron II sulfate.
Claim 13
Dependent Claim
17 words
A process according to claim 4 wherein said member is calcium ferrocyanide as the sole ferrocyanide employed.
Claim 14
Dependent Claim
33 words
A process according to claim 12 wherein the calcium ferrocyanide is employed in the form of the aqueous mixture prepared by reacting calcium hydroxide, hydrocyanic acid and a water soluble iron II salt.
Claim 15
Dependent Claim
17 words
A process according to claim 4 wherein said member is sodium ferrocyanide as the sole ferrocyanide employed.
Claim 16
Dependent Claim
17 words
A process according to claim 4 wherein the pH is from below 1 to up to 6.
Claim 17
Dependent Claim
22 words
A process according to claim 4 wherein the water soluble iron salt is added as a pure aqueous iron II chloride solution.
Claim 18
Dependent Claim
19 words
A process according to claim 4 wherein the water soluble iron salt is added as a pickling acid solution.
Claim 19
Dependent Claim
20 words
A process according to claim 17 wherein the pickling acid contains iron II chloride, nickel II chloride and zinc chloride.
Claim 20
Dependent Claim
23 words
A process according to claim 4 wherein the pH is kept at a value not over 1 until the Berlin white is formed.
Claim 21
Dependent Claim
43 words
A process according to claim 4 wherein the conversion of the acidic iron II salt of ferrocyanic salt to Berlin white is carried out at a temperature of 60*C. to the boiling point of the solution in the presence of the potassium salt.
Claim 22
Dependent Claim
15 words
A process according to claim 20 wherein the reaction is carried out at atmospheric pressure.
Claim 23
Dependent Claim
21 words
A process according to claim 2 wherein the formation of acidic iron II ferrocyanide is carried out at 25* to 60*C.
Claim 24
Dependent Claim
21 words
A process according to claim 3 wherein the formation of acidic iron II ferrocyanide is carried out at 25* to 60*C.
Claim 25
Dependent Claim
19 words
A process according to claim 23 wherein the formation of acidic iron II ferrocyanide is carried out at 40*C.
Claim 26
Dependent Claim
12 words
A process according to claim 2 wherein the ferrocyanide is magnesium ferrocyanide.
Claim 27
Dependent Claim
22 words
A process according to claim 25 wherein the pH in the two steps of forming the Berlin white is maintained at 4-6.
Claim 28
Dependent Claim
14 words
A process according to claim 26 wherein the pH is maintained at about 5.
Claim 29
Dependent Claim
13 words
A process according to claim 1 wherein (a) is the sole ferrocyanide employed.
Claim 30
Dependent Claim
15 words
A process according to claim 28 wherein the reactants consist of (a), (b) and (c).
References Cited (Backward Citations)
US2005697A
Cited
US2005698A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |