Prussian blue = ferric ferrocyanide

While in the donor s possession, the painting was scratched by a cat. An art conservator who was asked to repair the damage became suspicious about the blue paint used to render the girl s hat and the wallpaper. Subsequent analysis of microscopic samples of the paint revealed that the pigment was Prussian blue (ferric ferrocyanide, Fe4[Fe(CN)6]3), a coordination compound discovered by a German dyemaker between 1704 and 1707. 

Water-soluble crystal modifiers such as yellow pmssiate of soda (YPS) (sodium ferrocyanide decahydrate) or ferric ammonium citrate may also be added to some types of salt as anticaking agents. Both are approved by the U.S. Food and Dmg Administration for use in food-grade salt. YPS and Prussian Blue (ferric ferrocyanide), are most commonly added to rock salt used for wintertime highway deicing. Concentrations of YPS and Prussian Blue in deicing salt vary, typically in the range of 20—100 ppm. 

Prussian blue (ferric ferrocyanide) is the mainstay of therapy in Europe. This compound has a crystal lattice stmcture, which binds thallium ions and intermpts enterohepatic recycling. The recommended dose is 250 mg/kg/day via nasogastric tube in 2-4 divided doses, and administration is continued until urinary thallium excretion is less than 0.5 mg/24 h. Pmss-ian blue appears to be nontoxic at these doses. In the United States, Pmssian blue is available as an investigational new dmg (IND) through the Oak Ridge Associated Universities ([865] 576-3131 or [865] 576-3300). 

Chlorinated rubber, e.g. Duroprene (ICI Figure A3.7), is a saturated polymer. Although more stable than rubber, it is sensitive to light and ultraviolet, probably in a similar fashion to PVC, resulting in oxidation and discoloration. Chlorinated rubber can react with various pigments such as zinc oxide, copper salts, Prussian blue (ferric ferrocyanide) and ultramarine to form cross-Unks. 

Ferric chloride solution is then added to com ert the sodium ferrocyanide to the deep blue ferric ferrocyanide (or Prussian Blue), dilute sulphuric acid being also added to dissolve any ferrous and ferric hydroxides present in the other-... 

Upon boiling the alkaline ferrous salt solution, some ferric ions are inevitably produced by the action of the air upon the addition of dilute siilphurio acid, thus dissolving the ferrous and ferric hydroxides, the ferrocyanides reacts with the ferric salt producing ferric ferrocyanide (Prussian blue) ... 

Ferrifeiro-cyanid, n. ferric ferrocyanide (Prussian blue), -jodid, n. ferroeoferric iodide, -oxyd, n. ferroeoferric oxide, iron(II,III) oxide. 

Ferrocyan, n. ferrocyanogen. -eisen, n. ferric ferrocyanide (Prussian blue). 

Prussian blue (PB ferric ferrocyanide, or iron(III) hexacyanoferrate(II)) was first made by Diesbach in Berlin in 1704.88 It is extensively used as a pigment in the formulation of paints, lacquers, and printing inks.89,90 Since the first report91 in 1978 of the electrochemistry of PB films, numerous studies concerning the electrochemistry of PB and related analogs have been made,92 with proposed applications in electrochromism1 and electrochemical sensing and catalysis 93... 

The fact that Prussian blue is indeed ferric ferrocyanide (Fe4in[Fen(CN)6]3) with iron(III) atom coordinated to nitrogen and iron(II) atom coordinated to carbon has been established by spectroscopic investigations [4], Prussian blue can be synthesized chemically by the mixing of ferric (ferrous) and hexacyanoferrate ions with different oxidation state of iron atoms either Fe3+ + [Fen(CN)6]4 or Fe2+ + [Fem(CN)6]3. After mixing, an immediate formation of the dark blue colloid is observed. However, the mixed solutions of ferric (ferrous) and hexacyanoferrate ions with the same oxidation state of iron atoms are apparently stable. 

Prussian blue (inorgchem) Fe4 Fe(CN)6 3 Ferric ferrocyanide, used as a blue pigment and in the removal of hydrogen sulfide from gases. prash an blu j prussic acid See hydrocyanic acid. pras ik as ad ... 

Such cyanide complexes are also known for several other metals. All the fer-rocyanide complexes may be considered as the salts of ferrocyanic acid H4Fe(CN)e and ferricyanide complexes are that of ferricyanic acid, H3Fe(CN)e. The iron-cyanide complexes of alkali and alkaline-earth metals are water soluble. These metals form yellow and ruby-red salts with ferro-cyanide and ferricyanide complex anions, respectively. A few of the hexa-cyanoferrate salts have found major commercial applications. Probably, the most important among them is ferric ferrocyanide, FeFe(CN)e, also known as Prussian blue. The names, formulas and the CAS registry numbers of some hexacyanoferrate complexes are given below. Prussian blue and a few other important complexes of this broad class of substances are noted briefly in the following sections ... 

Ferric ferrocyanide [tetrairon(III) tris(hexakiscyanoferrate)(Prussian blue) Fe "4[Fe(CN)6]3 [14038-43-8]... 

Prussian blue or ferric ferrocyanide or iron(lll) hexakis(cyanoferrate(3—)) has the formula Fe4[Fe(CN)6]3. There are several commercial applications. It is used as pigment for paints, inks, typewriter ribbons, alkyd resins, enamels. 

Perhaps the most spectacular secret ink is Prussian blue, which forms by means of a chemical reaction between ferric sulfate and potassium ferrocyanide. Generally, a message written with ferric sulfate solution will be revealed when it is sprayed with ferrocyanide. A spy can soak fabric with each of these solutions and transport secret information without detection. During World War ii a German spy named George Vaux Bacon made notations on his socks and cloth buttons with the secret ink reagents. He, too, was caught and executed. 

TO EACH, ADD A FEW DROPS OF SOLUTION OF /4 TEASPOON POTASSIUM FERROCYANIDE IN 50 ml WATER. FERRIC SALT MAKES A DEEP BLUE PRECIPITATE OF PRUSSIAN BLUE. FERROUS SALT MAKES LIGHT BLUE PRECIPITATE. 

A large number of polymeric complexes is known containing ambidentate cyanide bridging groups. These are related to Prussian blue, which is formed by the addition of ferric salts to ferrocyanides ... 

On the basis of the foregoing generalization, it is reasonable to postulate that the simple transition metal cyanides with six or less d electrons will adopt the Prussian blue structure. However, metal cyanides with seven or more d electrons will crystallize in less symmetric structures. At the present there are insufficient data to thoroughly check this proposal, but the few known structures lend support to the idea. For example, ferrous cyanide (ferrous ferrocyanide) and ferric cyanide (ferric ferri-cyanide) crystallize with the Prussian blue structure while nickel and zinc cyanides do not. 

Figure 4 The structure of Prussian blue and related compounds. If none of the cube centre sites are occupied, the structure is that of ferric ferricyanide (both black and white Fe positions occupied by Fe111) if every second cube centre site (marked with a dotted circle) is occupied by K+, the structure is that of soluble Prussian blue (black = Fe11, white = Fe111) if all the centre sites are occupied by K+ (crosses as well as dotted circles) the structure is that of dipotassium ferrous ferrocyanide...

Another example of pigment identification by IR microspectroscopy is shown in Figure 10. The bottom spectrum was obtained from a blue pigment from MS 972 (Archaic Mark) the top spectrum is a reference spectrum of Prussian blue. The band corresponding to the C=N of ferric ferrocyanide is common to both spectra. Replicate spectra of blue pigments removed from different locations in MS 972 indicate that the average frequency of this band is 2083 6 cm"1. The ubiquitousness of an iron blue in this manuscript raises doubts about the authenticity of this manuscript. 

When a solution of potassium ferrocyanide reacts with rather less than one equivalent of a ferric salt, a blue hydrated precipitate of a-soluble Prussian blue, or ferric potassium ferrocyanide Fe K[Fe (CN)6], is obtained. Now, Hofmann and his co-workers 5 have shown that this precipitate is identical with that prepared under precisely similar conditions by the addition of a ferrous salt to potassium fcrricyanide, although in this case ferrous potassium ferricyanide, Fe K[Fe (CN)6], might be expected. It is therefore assumed that the latter salt is unstable, and, at the moment of formation, undergoes intramolecular rearrangement to the former complex. 

The Prussian Blues.—Several of these are known, namely a soluble Prussian blue, 4Fe K[Fe (CN)6].7H20. This compound is obtained when a solution of potassium ferrocyanide interacts with rather less than one equivalent of a ferric salt.6 It occurs as a deep... 

Commercial Preparation and Uses of Prussian Blue.—Prussian blue was discovered accidentally in 1704 by Diesbach,4 and is highly valued as a pigment on account of its remarkable intensity of colour. It was manufactured in Great Britain in 1770, and sold at 2 guineas per lb. One pound of Prussian blue will perceptibly tinge some 600 lbs. of white lead. The pigment is sometimes prepared commercially by the direct method of adding a ferric salt to a solution of potassium ferrocyanide but it is more usual to adopt an indirect method, namely to add a ferrous salt to potassium ferrocyanide and subsequently to oxidise the white precipitated mass of ferrous potassium ferrocyanide.5 Chemically it consists of a variable mixture of some or all of the Prussian blues already described. 

Addition of ferric chloride to certain liquors produced in the manufacture of Prussian blue in a French factory by the methylamine method (see p. 213) resulted in the precipitation of a violet compound.1 Several hundred grams of this were isolated by Muller, warmed with potassium carbonate and hydroxide successively, and the filtered solution allowed to crystallise. The product thus isolated crystallised in thin scales and rectangular prisms, and proved to be the potassium salt of an entirely new acid, namely hydrogen carbonyl ferrocyanide, H3Fe(CN)5.CO. Following up this discovery, Muller succeeded in preparing a series of well-defined salts. 

Ferric ferrocyanide, commonly known as Prussian blue (PB), was first synthesized > 300 years ago (39) and is still used in the manufacture of blueprints. Prussian blue is a prototypical mixed-valence compound with formula Fe 4[Fe (CN)6]3 I4H2O. In its canonical form, the pigment consists of ferrocyanide anions linked by Fe cations (Fig. 1) to form an extended pcu network. A defect structure that arises from the necessity of charge balancing in the cubic framework results in vacancies at 25% of the [Fe(CN)6]" sites (40). Analogous compounds are formed when one or both iron atoms are replaced by a variety of other metals. This substitution affords compounds of the formula M [My(CN)6]j where M and M can be Cr, Mn, Fe, Co, and many others, and where x andy depend on the identity and oxidation states of the metals. Because of their structural similarities we will refer to the entire class of compounds as blues PBs. 

Prussian blue Fe4[Fe(CN)6]3 can bind cesium therefore it is used in clinical practice as an antidote for the treatment of humans contaminated with radioactive cesium (see also Section 3.6.4). CUnical use of ferric ferrocyanide in doses up to 20 g d for decontaminations of persons exposed to radiocesium has not been associated with any reported toxicity [3.201]. 

This method for determining reducing sugars (7) is based on the reduction of ferricyanide ions in alkaline solution by a reducing sugar. The ferrocyanide produced can then react with a second mole of ferricyanide producing the ferric-ferrocyanide (Prussian blue) complex. Potassium... 

The pigments Prussian blue and TurnbulFs blue are made by addition of ferrous ion to a ferricyanide solution or ferric ion to a ferrocyanide solution. The pigments which precipitate have the approximate composition KFeFe(CN)g HoO. They have a brilliant blue color. Ferrous ion and ferrocyanide ion produce a white precipitate of KoFeFe(CN)6, whereas ferric ion and ferricyanide ion do not form a precipitate, but only a brown solution,... 

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