Re: 普鲁士蓝解毒机理 (转载)# WaterWorld - 未名水世界
f*r
1 楼
【 以下文字转载自 Military 讨论区 】
发信人: smartkevin (PE), 信区: Military
标 题: Re: 普鲁士蓝解毒机理
发信站: BBS 未名空间站 (Wed May 1 11:49:11 2013, 美东)
为什么一帮人就喜欢动嘴皮子不喜欢动手狗一下？明明说了是Fe4[Fe(CN)6]3，哪来的
钾？
https://en.wikipedia.org/wiki/Prussian_blue
Prussian blue
From Wikipedia, the free encyclopedia
This article is about the pigment. For the musical duo, see Prussian Blue.
See also: Midnight blue
Prussian blue
IUPAC name[hide]
Iron(II,III) hexacyanoferrate(II,III)
Other names[hide]
Berlin blue
Ferric ferrocyanide
Ferric hexacyanoferrate
Iron(III) ferrocyanide
Iron(III) hexacyanoferrate(II)
Parisian blue
Identifiers
CAS number 14038-43-8
PubChem 2724251
ChemSpider 20074656
UNII TLE294X33A
EC number 237-875-5
ChEBI CHEBI:30069
ChEMBL CHEMBL2096629
ATC code V03AB31
Gmelin Reference 1093743
Jmol-3D images Image 1
SMILES
[show]
InChI
[show]
Properties
Molecular formula C18Fe7N18
Molar mass 859.23 g molㄢ
Appearance Blue opaque crystals
Pharmacology
Routes of
administration Oral
Hazards
MSDS MSDS prussian blue
Related compounds
Other cations Potassium ferrocyanide
Sodium ferrocyanide
(verify) (what is: /?)
Except where noted otherwise, data are given for materials in their standard
state (at 25 °C, 100 kPa)
Infobox references
Prussian blue is a dark blue pigment with the idealized formula Fe7(CN)18.
Another name for the color Prussian blue is Berlin blue or, in painting,
Parisian blue. Turnbull's blue is the same substance but is made from
different reagents, and its slightly different color stems from different
impurities.
Prussian blue was one of the first synthetic pigments. It is employed as a
very fine colloidal dispersion, as the compound itself is not soluble in
water. It is famously complex,[1] owing to the presence of variable amounts
of other ions and the sensitive dependence of its appearance on the size of
the colloidal particles formed when it is made. The pigment is used in
paints, and it is the traditional "blue" in blueprints.
In medicine, Prussian blue is used as an antidote for certain kinds of heavy
metal poisoning, e.g., by cesium and thallium. In particular it was used to
absorb 137Cs+ from those poisoned in the Goi渀椀愀 accident.[1] Prussian
Blue is orally administered. The therapy exploits Prussian Blue's ion
exchange properties and high affinity for certain "soft" metal cations.
Prussian blue lent its name to prussic acid, which was derived from it, and
to ferrocyanide (originally meaning "blue compound of iron", from Latin
ferrum and Ancient Greek κυνεο, kuaneos). As ferrocyanide is made of
iron and CN ligands, reinterpreting the component "-cyanide" in the compound
word produced the word "cyanide" for compounds containing the CN radical.
Contents [hide]
1 History
2 Production
2.1 "Turnbull's blue"
3 Properties
3.1 Crystal structure
3.2 Color
4 Uses
4.1 Pigment
4.2 Medicine
4.3 Laboratory histopathology stain for iron
4.4 By machinists and toolmakers
4.5 Analytical chemistry
5 Safety
6 Military
7 See also
8 References
9 External links
[edit]History
Prussian blue [Fe4[Fe(CN)6]3] was probably synthesized for the first time by
the paint maker Diesbach in Berlin around the year 1706.[2] Most historical
sources do not mention a first name of Diesbach. Only Berger refers to him
as Johann Jacob Diesbach.[3] It was named "Preu椀猀挀栀 blau" and "
Berlinisch Blau" in 1709 by its first trader.[4] The pigment replaced the
expensive Lapis lazuli and was an important topic in the letters exchanged
between Johann Leonhard Frisch[5] and the president of the Royal Academy of
Sciences, Gottfried Wilhelm Leibniz, between 1708 and 1716.[4] It is first
mentioned in a letter written by Frisch to Leibniz, from March 31, 1708. Not
later than 1708, Frisch began to promote and sell the pigment across Europe
. By August 1709, the pigment had been termed "Preussisch blau"; by November
1709, the German name "Berlinisch Blau" had been used for the first time by
Frisch. Frisch himself is the author of the first known publication of
Prussian blue in the paper Notitia Coerulei Berolinensis nuper inventi in
1710, as can be deduced from his letters. Diesbach had been working for
Frisch since about 1701.
In 1731, Georg Ernst Stahl published an account of the first synthesis of
Prussian blue.[6] The story involves not only Diesbach but also Johann
Konrad Dippel. Diesbach was attempting to create a red lake pigment from
cochineal but obtained the blue instead as a result of the contaminated
potash he was using. He borrowed the potash from Dippel, who had used it to
produce his "animal oil". No other known historical source mentions Dippel
in this context. It is therefore difficult to judge the reliability of this
story today. In 1724, the recipe was finally published by John Woodward.[7][
8][9]
To date, the "Entombment of Christ", dated 1709 by Pieter van der Werff (
Picture Gallery, Sanssouci, Potsdam) is the oldest known painting where
Prussian blue was used. Around 1710, painters at the Prussian court were
already using the pigment. At around the same time, Prussian blue arrived in
Paris, where Antoine Watteau and later his successors Nicolas Lancret and
Jean-Baptiste Pater used it in their paintings.[10]
"The Great Wave off Kanagawa" by Hokusai, a famous artwork which makes
extensive use of Prussian blue.
This Prussian blue pigment is significant since it was the first stable and
relatively lightfast blue pigment to be widely used following the loss of
knowledge regarding the synthesis of Egyptian blue. European painters had
previously used a number of pigments such as indigo dye, smalt, and Tyrian
purple, which tend to fade, and the extremely expensive ultramarine made
from lapis lazuli. Japanese painters and woodblock print artists likewise
did not have access to a long-lasting blue pigment until they began to
import Prussian blue from Europe.
In 1752 the French chemist Pierre J. Macquer made the important step of
showing the Prussian blue could be reduced to a salt of iron and a new acid,
which could be used to reconstitute the dye.[11] The new acid, hydrogen
cyanide, first isolated from Prussian blue in pure form and characterized
about 1783 by the Swedish chemist Carl Wilhelm Scheele, was eventually given
the name Blaus甀爀攀 (literally "Blue acid") because of its derivation from
Prussian blue, and in English became known popularly as Prussic acid.
Prussian blue would also give the name to the ferrocyanide and cyanide
family of compounds. Ferrocyanide (which is yellow) was coined as Neo Latin
for "iron-containing blue material", since it was first isolated from
Prussian blue. Cyanide, a colorless anion that forms in the process of
making Prussian Blue, was named, in turn, for hydrogen cyanide (also
colorless), and ultimately from ferrocyanide. It is for this reason that
cyanide, even though the name of a colorless radical, is a Latinized form of
the Greek word for "dark blue."
[edit]Production
Prussian blue is produced by oxidation of ferrous ferrocyanide salts. These
white solids have the formula M2Fe[Fe(CN)6] where M+ = Na+ or K+. The iron
in this material is all ferrous, hence the absence of deep color associated
with the mixed valency. Oxidation of this white solid with hydrogen peroxide
or sodium chlorate produces ferricyanide and affords Prussian Blue.[12]
A "soluble" form of PB, K[FeIIIFeII(CN)6], which is really colloidal, can be
made from potassium ferrocyanide and iron(III):
K+ + Fe3+ + [FeII(CN)6]4- → KFeIII[FeII(CN)6]
The similar reaction of potassium ferricyanide and iron(II) results in the
same colloidal solution, because [FeIII(CN)6]3- is converted into
ferrocyanide.
"Insoluble" Prussian blue is produced if in the reactions above an excess of
Fe3+ or Fe2+, respectively, is added. In the first case:
4Fe3+ + 3[FeII(CN)6]4- → FeIII[FeIIIFeII(CN)6]3 [13]
[edit]"Turnbull's blue"
Ferricyanide ion, used to make 'Turnbull's blue'.
In former times, it was thought that addition of Fe(II) salts to a solution
of ferricyanide affords a material different from Prussian blue. The product
was traditionally named "Turnbull's Blue" (TB). It has been shown, however,
by means of X-ray diffraction and electron diffraction methods, that the
structures of PB and TB are identical.[14][15] The differences in the colors
for TB and PB reflect subtle differences in the method of precipitation,
which strongly affects particle size and impurity content.
[edit]Properties
Prussian blue is a microcrystalline blue powder. It is insoluble, but the
crystallites tend to form a colloid. Such colloids can pass through fine
filters.[1] Despite being one of the oldest known synthetic compounds, the
composition of Prussian blue remained uncertain for many years. The precise
identification of Prussian blue was complicated by three factors:
Prussian blue is extremely insoluble but also tends to form colloids;
Traditional syntheses tend to afford impure compositions;
Even pure Prussian blue is structurally complex, defying routine
crystallographic analysis.
[edit]Crystal structure
The chemical formula of insoluble Prussian blue is Fe7(CN)18·xH2O, where x
= 14–16. The structure was determined by using IR spectroscopy, Moessbauer
spectroscopy, X-ray crystallography, and neutron crystallography. Since X-
ray diffraction cannot distinguish carbon from nitrogen, the location of
these lighter elements is deduced by spectroscopic means as well as by
observing the distances from the iron atom centers.
PB has a cubic lattice structure. Soluble PB crystals contain interstitial K
+ ions; insoluble PB has interstitial water instead.
In ideal insoluble PB crystals, the cubic framework is built from Fe(II)-C-N
-Fe(III) sequences, with Fe(II)-carbon distances of 1.92 and Fe(III)-
nitrogen distances of 2.03 . One-fourth of the sites of Fe(CN)6 subunits are
vacant (empty), leaving three such groups. The empty nitrogen sites are
filled with water molecules instead, which are coordinated to Fe(III).
The Fe(II) centers, which are low spin, are surrounded by six carbon ligands
in an octahedral configuration. The Fe(III) centers, which are high spin,
are octahedrally surrounded on average by 4.5 nitrogen atoms and 1.5 oxygen
atoms (the oxygen from the six coordinated water molecules). Additional
eight (interstitial) water molecules are present in the unit cell, either as
isolated molecules or hydrogen bonded to the coordinated water.
The composition is notoriously variable due to the presence of lattice
defects, allowing it to be hydrated to various degrees as water molecules
are incorporated into the structure to occupy cation vacancies. The
variability of Prussian blue's composition is attributable to its low
solubility, which leads to its rapid precipitation without the time to
achieve full equilibrium between solid and liquid.[16] [17]
[edit]Color
Prussian blue is strongly colored and tends towards black and dark blue when
mixed into oil paints. The exact hue depends on the method of preparation,
which dictates the particle size. The intense blue color of Prussian blue is
associated with the energy of the transfer of electrons from Fe(II) to Fe(
III). Many such mixed-valence compounds absorb certain wavelengths of
visible light resulting from intervalence charge transfer. In this case,
orange-red light around 680 nanometers in wavelength is absorbed, and the
reflected light appears blue as a result.
Like most high chroma pigments, Prussian blue cannot be accurately displayed
on a computer display.
PB is electrochromic—changing from blue to colorless upon reduction. This
change is caused by reduction of the Fe(III) to Fe(II) eliminating the
intervalence charge transfer that causes Prussian blue's color.
[edit]Uses
[edit]Pigment
Because it is easily made, cheap, non-toxic, and intensely colored, Prussian
blue has attracted many applications. It was adopted as a pigment very soon
after its invention and was almost immediately widely used in oil,
watercolor and dyeing.[18] The dominant uses are for pigments: approximately
12,000 tonnes of Prussian blue are produced annually for use in black and
bluish inks. A variety of other pigments also contain the material.[12]
Engineer's blue and the pigment formed on cyanotypes—giving them their
common name blueprints. Certain crayons were once colored with Prussian blue
(later relabeled Midnight Blue). It is also a popular pigment in paints.
Similarly, Prussian blue is the basis for laundry bluing.
[edit]Medicine
Prussian blue's ability to incorporate monocations makes it useful as a
sequestering agent for certain heavy metal poisons. Pharmaceutical-grade
Prussian blue in particular is used for patients who have ingested thallium
or radioactive caesium. According to the International Atomic Energy Agency,
an adult male can eat at least 10 grams of Prussian blue per day without
serious harm. The U.S. Food and Drug Administration (FDA) has determined
that the "500 mg Prussian blue capsules, when manufactured under the
conditions of an approved New Drug Application (NDA), can be found safe and
effective therapy" in certain poisoning cases.[19] Radiogardase (Prussian
blue in soluble capsules [20]) is a commercial product for the removal of
caesium-137 from the intestine and so indirectly from the bloodstream by
intervening in the enterohepatic circulation of caesium-137,[21] reducing
the internal residency time (and exposure) by about two-thirds.
[edit]Laboratory histopathology stain for iron
Prussian blue stain
Prussian blue is a common histopathology stain used by pathologists to
detect the presence of iron in biopsy specimens, such as in bone marrow
samples. The original stain formula, known historically (1867) as "Perls'
Prussian blue" after its inventor, German pathologist Max Perls (1843–1881)
, used separate solutions of potassium ferrocyanide and acid to stain tissue
(these are now used combined, just before staining). Iron deposits in
tissue then form the purple Prussian blue dye in place, and are visualized
as blue or purple deposits.[22] The formula is also known as Perls Prussian
blue and (incorrectly) as Perl's Prussian blue.
[edit]By machinists and toolmakers
Prussian blue in oil paint is the traditional material used for spotting
metal surfaces such as surface plates and bearings for hand scraping. A thin
layer of non-drying paste is applied to a reference surface and transfers
to the high spots of the workpiece. The toolmaker then scrapes, stones, or
otherwise removes the marked high spots. Prussian blue is preferable because
it will not abrade the extremely precise reference surfaces as many ground
pigments may.
[edit]Analytical chemistry
Prussian blue is formed in the Prussian blue assay for total phenols.
Samples and phenolic standards are given acidic ferric chloride and
ferricyanide which is reduced to ferrocyanide by the phenols. The ferric
chloride and ferrocyanide react to form Prussian blue. Comparing the
absorbance at 700 nm of the samples to the standards allows for the
determination of total phenols or polyphenols.[23][24]
[edit]Safety
Despite the fact that it is prepared from cyanide salts, Prussian blue is
nontoxic because the cyanide groups are tightly bound to Fe. Other polymeric
cyanometalates are similarly stable with low toxicity.[citation needed]
[edit]Military
From the beginning of the 18th century Prussian blue was the predominant
uniform coat color worn by the infantry and artillery regiments of the
Prussian Army.[25] As Dunkelblau this shade achieved a symbolic importance
and continued to be worn for ceremonial and off-duty occasions until the
outbreak of World War I.[26]
发信人: smartkevin (PE), 信区: Military
标 题: Re: 普鲁士蓝解毒机理
发信站: BBS 未名空间站 (Wed May 1 11:49:11 2013, 美东)
为什么一帮人就喜欢动嘴皮子不喜欢动手狗一下？明明说了是Fe4[Fe(CN)6]3，哪来的
钾？
https://en.wikipedia.org/wiki/Prussian_blue
Prussian blue
From Wikipedia, the free encyclopedia
This article is about the pigment. For the musical duo, see Prussian Blue.
See also: Midnight blue
Prussian blue
IUPAC name[hide]
Iron(II,III) hexacyanoferrate(II,III)
Other names[hide]
Berlin blue
Ferric ferrocyanide
Ferric hexacyanoferrate
Iron(III) ferrocyanide
Iron(III) hexacyanoferrate(II)
Parisian blue
Identifiers
CAS number 14038-43-8
PubChem 2724251
ChemSpider 20074656
UNII TLE294X33A
EC number 237-875-5
ChEBI CHEBI:30069
ChEMBL CHEMBL2096629
ATC code V03AB31
Gmelin Reference 1093743
Jmol-3D images Image 1
SMILES
[show]
InChI
[show]
Properties
Molecular formula C18Fe7N18
Molar mass 859.23 g molㄢ
Appearance Blue opaque crystals
Pharmacology
Routes of
administration Oral
Hazards
MSDS MSDS prussian blue
Related compounds
Other cations Potassium ferrocyanide
Sodium ferrocyanide
(verify) (what is: /?)
Except where noted otherwise, data are given for materials in their standard
state (at 25 °C, 100 kPa)
Infobox references
Prussian blue is a dark blue pigment with the idealized formula Fe7(CN)18.
Another name for the color Prussian blue is Berlin blue or, in painting,
Parisian blue. Turnbull's blue is the same substance but is made from
different reagents, and its slightly different color stems from different
impurities.
Prussian blue was one of the first synthetic pigments. It is employed as a
very fine colloidal dispersion, as the compound itself is not soluble in
water. It is famously complex,[1] owing to the presence of variable amounts
of other ions and the sensitive dependence of its appearance on the size of
the colloidal particles formed when it is made. The pigment is used in
paints, and it is the traditional "blue" in blueprints.
In medicine, Prussian blue is used as an antidote for certain kinds of heavy
metal poisoning, e.g., by cesium and thallium. In particular it was used to
absorb 137Cs+ from those poisoned in the Goi渀椀愀 accident.[1] Prussian
Blue is orally administered. The therapy exploits Prussian Blue's ion
exchange properties and high affinity for certain "soft" metal cations.
Prussian blue lent its name to prussic acid, which was derived from it, and
to ferrocyanide (originally meaning "blue compound of iron", from Latin
ferrum and Ancient Greek κυνεο, kuaneos). As ferrocyanide is made of
iron and CN ligands, reinterpreting the component "-cyanide" in the compound
word produced the word "cyanide" for compounds containing the CN radical.
Contents [hide]
1 History
2 Production
2.1 "Turnbull's blue"
3 Properties
3.1 Crystal structure
3.2 Color
4 Uses
4.1 Pigment
4.2 Medicine
4.3 Laboratory histopathology stain for iron
4.4 By machinists and toolmakers
4.5 Analytical chemistry
5 Safety
6 Military
7 See also
8 References
9 External links
[edit]History
Prussian blue [Fe4[Fe(CN)6]3] was probably synthesized for the first time by
the paint maker Diesbach in Berlin around the year 1706.[2] Most historical
sources do not mention a first name of Diesbach. Only Berger refers to him
as Johann Jacob Diesbach.[3] It was named "Preu椀猀挀栀 blau" and "
Berlinisch Blau" in 1709 by its first trader.[4] The pigment replaced the
expensive Lapis lazuli and was an important topic in the letters exchanged
between Johann Leonhard Frisch[5] and the president of the Royal Academy of
Sciences, Gottfried Wilhelm Leibniz, between 1708 and 1716.[4] It is first
mentioned in a letter written by Frisch to Leibniz, from March 31, 1708. Not
later than 1708, Frisch began to promote and sell the pigment across Europe
. By August 1709, the pigment had been termed "Preussisch blau"; by November
1709, the German name "Berlinisch Blau" had been used for the first time by
Frisch. Frisch himself is the author of the first known publication of
Prussian blue in the paper Notitia Coerulei Berolinensis nuper inventi in
1710, as can be deduced from his letters. Diesbach had been working for
Frisch since about 1701.
In 1731, Georg Ernst Stahl published an account of the first synthesis of
Prussian blue.[6] The story involves not only Diesbach but also Johann
Konrad Dippel. Diesbach was attempting to create a red lake pigment from
cochineal but obtained the blue instead as a result of the contaminated
potash he was using. He borrowed the potash from Dippel, who had used it to
produce his "animal oil". No other known historical source mentions Dippel
in this context. It is therefore difficult to judge the reliability of this
story today. In 1724, the recipe was finally published by John Woodward.[7][
8][9]
To date, the "Entombment of Christ", dated 1709 by Pieter van der Werff (
Picture Gallery, Sanssouci, Potsdam) is the oldest known painting where
Prussian blue was used. Around 1710, painters at the Prussian court were
already using the pigment. At around the same time, Prussian blue arrived in
Paris, where Antoine Watteau and later his successors Nicolas Lancret and
Jean-Baptiste Pater used it in their paintings.[10]
"The Great Wave off Kanagawa" by Hokusai, a famous artwork which makes
extensive use of Prussian blue.
This Prussian blue pigment is significant since it was the first stable and
relatively lightfast blue pigment to be widely used following the loss of
knowledge regarding the synthesis of Egyptian blue. European painters had
previously used a number of pigments such as indigo dye, smalt, and Tyrian
purple, which tend to fade, and the extremely expensive ultramarine made
from lapis lazuli. Japanese painters and woodblock print artists likewise
did not have access to a long-lasting blue pigment until they began to
import Prussian blue from Europe.
In 1752 the French chemist Pierre J. Macquer made the important step of
showing the Prussian blue could be reduced to a salt of iron and a new acid,
which could be used to reconstitute the dye.[11] The new acid, hydrogen
cyanide, first isolated from Prussian blue in pure form and characterized
about 1783 by the Swedish chemist Carl Wilhelm Scheele, was eventually given
the name Blaus甀爀攀 (literally "Blue acid") because of its derivation from
Prussian blue, and in English became known popularly as Prussic acid.
Prussian blue would also give the name to the ferrocyanide and cyanide
family of compounds. Ferrocyanide (which is yellow) was coined as Neo Latin
for "iron-containing blue material", since it was first isolated from
Prussian blue. Cyanide, a colorless anion that forms in the process of
making Prussian Blue, was named, in turn, for hydrogen cyanide (also
colorless), and ultimately from ferrocyanide. It is for this reason that
cyanide, even though the name of a colorless radical, is a Latinized form of
the Greek word for "dark blue."
[edit]Production
Prussian blue is produced by oxidation of ferrous ferrocyanide salts. These
white solids have the formula M2Fe[Fe(CN)6] where M+ = Na+ or K+. The iron
in this material is all ferrous, hence the absence of deep color associated
with the mixed valency. Oxidation of this white solid with hydrogen peroxide
or sodium chlorate produces ferricyanide and affords Prussian Blue.[12]
A "soluble" form of PB, K[FeIIIFeII(CN)6], which is really colloidal, can be
made from potassium ferrocyanide and iron(III):
K+ + Fe3+ + [FeII(CN)6]4- → KFeIII[FeII(CN)6]
The similar reaction of potassium ferricyanide and iron(II) results in the
same colloidal solution, because [FeIII(CN)6]3- is converted into
ferrocyanide.
"Insoluble" Prussian blue is produced if in the reactions above an excess of
Fe3+ or Fe2+, respectively, is added. In the first case:
4Fe3+ + 3[FeII(CN)6]4- → FeIII[FeIIIFeII(CN)6]3 [13]
[edit]"Turnbull's blue"
Ferricyanide ion, used to make 'Turnbull's blue'.
In former times, it was thought that addition of Fe(II) salts to a solution
of ferricyanide affords a material different from Prussian blue. The product
was traditionally named "Turnbull's Blue" (TB). It has been shown, however,
by means of X-ray diffraction and electron diffraction methods, that the
structures of PB and TB are identical.[14][15] The differences in the colors
for TB and PB reflect subtle differences in the method of precipitation,
which strongly affects particle size and impurity content.
[edit]Properties
Prussian blue is a microcrystalline blue powder. It is insoluble, but the
crystallites tend to form a colloid. Such colloids can pass through fine
filters.[1] Despite being one of the oldest known synthetic compounds, the
composition of Prussian blue remained uncertain for many years. The precise
identification of Prussian blue was complicated by three factors:
Prussian blue is extremely insoluble but also tends to form colloids;
Traditional syntheses tend to afford impure compositions;
Even pure Prussian blue is structurally complex, defying routine
crystallographic analysis.
[edit]Crystal structure
The chemical formula of insoluble Prussian blue is Fe7(CN)18·xH2O, where x
= 14–16. The structure was determined by using IR spectroscopy, Moessbauer
spectroscopy, X-ray crystallography, and neutron crystallography. Since X-
ray diffraction cannot distinguish carbon from nitrogen, the location of
these lighter elements is deduced by spectroscopic means as well as by
observing the distances from the iron atom centers.
PB has a cubic lattice structure. Soluble PB crystals contain interstitial K
+ ions; insoluble PB has interstitial water instead.
In ideal insoluble PB crystals, the cubic framework is built from Fe(II)-C-N
-Fe(III) sequences, with Fe(II)-carbon distances of 1.92 and Fe(III)-
nitrogen distances of 2.03 . One-fourth of the sites of Fe(CN)6 subunits are
vacant (empty), leaving three such groups. The empty nitrogen sites are
filled with water molecules instead, which are coordinated to Fe(III).
The Fe(II) centers, which are low spin, are surrounded by six carbon ligands
in an octahedral configuration. The Fe(III) centers, which are high spin,
are octahedrally surrounded on average by 4.5 nitrogen atoms and 1.5 oxygen
atoms (the oxygen from the six coordinated water molecules). Additional
eight (interstitial) water molecules are present in the unit cell, either as
isolated molecules or hydrogen bonded to the coordinated water.
The composition is notoriously variable due to the presence of lattice
defects, allowing it to be hydrated to various degrees as water molecules
are incorporated into the structure to occupy cation vacancies. The
variability of Prussian blue's composition is attributable to its low
solubility, which leads to its rapid precipitation without the time to
achieve full equilibrium between solid and liquid.[16] [17]
[edit]Color
Prussian blue is strongly colored and tends towards black and dark blue when
mixed into oil paints. The exact hue depends on the method of preparation,
which dictates the particle size. The intense blue color of Prussian blue is
associated with the energy of the transfer of electrons from Fe(II) to Fe(
III). Many such mixed-valence compounds absorb certain wavelengths of
visible light resulting from intervalence charge transfer. In this case,
orange-red light around 680 nanometers in wavelength is absorbed, and the
reflected light appears blue as a result.
Like most high chroma pigments, Prussian blue cannot be accurately displayed
on a computer display.
PB is electrochromic—changing from blue to colorless upon reduction. This
change is caused by reduction of the Fe(III) to Fe(II) eliminating the
intervalence charge transfer that causes Prussian blue's color.
[edit]Uses
[edit]Pigment
Because it is easily made, cheap, non-toxic, and intensely colored, Prussian
blue has attracted many applications. It was adopted as a pigment very soon
after its invention and was almost immediately widely used in oil,
watercolor and dyeing.[18] The dominant uses are for pigments: approximately
12,000 tonnes of Prussian blue are produced annually for use in black and
bluish inks. A variety of other pigments also contain the material.[12]
Engineer's blue and the pigment formed on cyanotypes—giving them their
common name blueprints. Certain crayons were once colored with Prussian blue
(later relabeled Midnight Blue). It is also a popular pigment in paints.
Similarly, Prussian blue is the basis for laundry bluing.
[edit]Medicine
Prussian blue's ability to incorporate monocations makes it useful as a
sequestering agent for certain heavy metal poisons. Pharmaceutical-grade
Prussian blue in particular is used for patients who have ingested thallium
or radioactive caesium. According to the International Atomic Energy Agency,
an adult male can eat at least 10 grams of Prussian blue per day without
serious harm. The U.S. Food and Drug Administration (FDA) has determined
that the "500 mg Prussian blue capsules, when manufactured under the
conditions of an approved New Drug Application (NDA), can be found safe and
effective therapy" in certain poisoning cases.[19] Radiogardase (Prussian
blue in soluble capsules [20]) is a commercial product for the removal of
caesium-137 from the intestine and so indirectly from the bloodstream by
intervening in the enterohepatic circulation of caesium-137,[21] reducing
the internal residency time (and exposure) by about two-thirds.
[edit]Laboratory histopathology stain for iron
Prussian blue stain
Prussian blue is a common histopathology stain used by pathologists to
detect the presence of iron in biopsy specimens, such as in bone marrow
samples. The original stain formula, known historically (1867) as "Perls'
Prussian blue" after its inventor, German pathologist Max Perls (1843–1881)
, used separate solutions of potassium ferrocyanide and acid to stain tissue
(these are now used combined, just before staining). Iron deposits in
tissue then form the purple Prussian blue dye in place, and are visualized
as blue or purple deposits.[22] The formula is also known as Perls Prussian
blue and (incorrectly) as Perl's Prussian blue.
[edit]By machinists and toolmakers
Prussian blue in oil paint is the traditional material used for spotting
metal surfaces such as surface plates and bearings for hand scraping. A thin
layer of non-drying paste is applied to a reference surface and transfers
to the high spots of the workpiece. The toolmaker then scrapes, stones, or
otherwise removes the marked high spots. Prussian blue is preferable because
it will not abrade the extremely precise reference surfaces as many ground
pigments may.
[edit]Analytical chemistry
Prussian blue is formed in the Prussian blue assay for total phenols.
Samples and phenolic standards are given acidic ferric chloride and
ferricyanide which is reduced to ferrocyanide by the phenols. The ferric
chloride and ferrocyanide react to form Prussian blue. Comparing the
absorbance at 700 nm of the samples to the standards allows for the
determination of total phenols or polyphenols.[23][24]
[edit]Safety
Despite the fact that it is prepared from cyanide salts, Prussian blue is
nontoxic because the cyanide groups are tightly bound to Fe. Other polymeric
cyanometalates are similarly stable with low toxicity.[citation needed]
[edit]Military
From the beginning of the 18th century Prussian blue was the predominant
uniform coat color worn by the infantry and artillery regiments of the
Prussian Army.[25] As Dunkelblau this shade achieved a symbolic importance
and continued to be worn for ceremonial and off-duty occasions until the
outbreak of World War I.[26]
