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Ferric(III) chloride is an important industrial chemical used for coagulation, etching, and various synthesis processes.
Ferric(III) chloride is especially effective in removing suspended impurities and phosphorus compounds from water and wastewater systems.
Ferric(III) chloride's high reactivity and strong acidic character make it suitable for demanding treatment and manufacturing applications.
CAS Number: 7705-08-0
EC Number: 231-729-4
Molecular Formula: Cl3Fe
Molecular Weight: 162.2 g/mol
Synonyms: FERRIC CHLORIDE, 7705-08-0, Iron trichloride, Iron chloride, Flores martis, Iron perchloride, Chlorure perrique, Perchlorure de fer, Iron chloride (FeCl3), Natural molysite, FERRIC CHLORIDE, ANHYDROUS, Chlorure ferrique, Iron sesquichloride (DOT), FeCl3, U38V3ZVV3V, Iron sesquichloride, CHEBI:30808, NSC-51150, NSC-135798, Ferric trichloride, RefChem:6640, 231-729-4, DTXCID60622, DTXSID8020622, Ferric chloride, hexahydrate, Iron (III), chloride, hexahydrate, Iron(3+) chloride, hexahydrate, Iron(III) chloride, trichloroiron, Iron (III) chloride, Iron chloride (Fe2Cl3), Caswell No. 459, Chlorure ferrique [French], Chlorure perrique [French], Perchlorure de fer [French], CCRIS 2299, HSDB 449, EINECS 231-729-4, NSC 51150, UN1773, UN2582, UNII-U38V3ZVV3V, EPA Pesticide Chemical Code 034901, NSC 135798, AI3-51902, Iron chloride, solid, Ferric chloride, solid, EC 231-729-4, WLN: FE G3, Iron(III) chloride anhydrous, Iron(III)chloride, Fe(III) chloride, iron (III)chloride, Fe/ppm Pd for nitro group reductions, iron(3+) chloride, iron (III) cloride, iron-(III) chloride, iron-(III)-chloride, Iron chloride anhydrous, iron (III) trichloride, [FeCl3], Iron(III) chloride, CP, SCHEMBL15401, Ferric chloride, anhydrous [UN1773] [Corrosive], TDA Reagent, for microbiology, orb2941054, NSC51150, Iron(III) chloride, p.a., 98%, NSC135798, TXB-00061, AKOS015902743, DB15536, NCGC00249131-01, BP-31268, Iron(III) chloride, reagent grade, 97%, Iron(III) chloride, technical grade, 58%, NS00093572, EN300-19478, Iron(III) chloride, LR, anhydrous, >=97%, USP Solution Ferric Chloride TS Conforms to USP, Iron (III) chloride, Trace metals grade, 99.9%, Q399771, Ferric chloride, anhydrous [UN1773] [Corrosive], F0001-1983, Ferric chloride hexahydrate, Iron trichloride hexahydrate, Iron(III) chloride, sublimed grade, >=99.9% trace metals basis, Iron(III) chloride, anhydrous, powder, >=99.99% trace metals basis, Iron(III) chloride on silica gel, powder, extent of labeling: 5 wt. % loading, 231-729-4, 7705-08-0, Chlorure ferrique, Eisen(3+)trichlorid, FERRIC CHLORIDE, Flores martis, Iron (III) chloride, iron trichloride, Iron(3+) trichloride, iron(iii) chloride, Molysite, TDA Reagent, Trichlorure de fer(3+), Tryptophan Deaminase Reagent, 10025-77-1, 1055987-64-8, 12040-57-2, 12178-83-5, 130622-20-7, 1326810-58-5, 231-729-4MFCD00011005, 58694-80-7, 98%, FE G3, FeCl3·6H2O, Ferric chloride, Iron trichloride, Ferric chloride,anhydrous, ferric trichloride, Ferricchloride, FerricChloride,Anhydrous, Flores martis, Iron chloride, Iron chloride, solid, Iron sesquichloride, Iron trichloride hexahydrate, iron(+3) cation trichloride, IRON(3+) ION TRICHLORIDE, Iron(III) chloride (anhydrous) Msynth®, Iron(III) chloride anhydrous, Iron(III) chloride hexahydrate, Iron(III) chloride, anhydrous, iron(iii)-chloride, iron(iii)chloride, molysite Cl3Fe, Perchlorure de fer, trichloroiron, 三氯化铁
Ferric(III) chloride is an inorganic compound with the formula FeCl3.
Ferric(III) chloride forms hydrates FeCl3·xH2O.
Ferric(III) chlorides are some of the most important and commonplace compounds of iron.
Ferric(III) chlorides are available both in anhydrous and in hydrated forms, which are both hygroscopic.
They feature iron in its +3 oxidation state.
The anhydrous derivative is a Lewis acid, while all forms are mild oxidizing agents.
Ferric(III) chloride is used as a water cleaner and as an etchant for metals.
Ferric(III) chloride is an orange to brown-black solid.
Ferric(III) chloride is slightly soluble in water.
Ferric(III) chloride is noncombustible.
When wet Ferric(III) chloride is corrosive to aluminum and most metals.
Pick up and remove spilled solid before adding water.
Ferric(III) chloride is used to treat sewage, industrial waste, to purify water, as an etching agent for engraving circuit boards, and in the manufacture of other chemicals.
Ferric(III) chloride, solution appears as a colorless to light brown aqueous solution that has a faint hydrochloric acid odor.
Highly corrosive to most metals and probably corrosive to tissue.
Ferric(III) chloride is noncombustible.
Ferric(III) chloride is used in sewage treatment and water purification.
Ferric(III) chloride is a mild oxidizing agent and participates in various carbon-carbon-bond forming reactions.
On crystallization with water, Ferric(III) chloride forms hydrates.
Ferric(III) chloride can be prepared by reacting chlorine with the scrap iron at approximately 650°C.
Ferric(III) chloride is an inorganic compound widely used as a coagulant, catalyst, etching agent, and chemical intermediate.
Ferric(III) chloride is commonly supplied as dark brown to black crystalline material, anhydrous powder, or as a yellow-brown aqueous solution.
Ferric(III) chloride is highly soluble in water and forms strongly acidic solutions through hydrolysis.
Ferric(III) chloride readily reacts with bases, reducing agents, and certain metals, and its strong Lewis acid character makes it useful in numerous chemical and industrial processes.
Ferric(III) chloride is extensively used in water and wastewater treatment, metal surface treatment, printed circuit board etching, pigment production, chemical synthesis, sewage treatment, and laboratory applications.
Ferric(III) chloride is used in the synthesis of organic compounds.
Ferric(III) chloride is also used in the Mayer′s tannic acid/ferric chloride method for staining tissue and their observation by light microscopy.
Studies of iron uptake and of apoptosis in cultured cells have utilized Ferric(III) chloride as an iron source.
Ferric(III) chloride is an industrial scale commodity chemical compound, with the formula FeCl3.
The colour of Ferric(III) chloride crystals depends on the viewing angle: by reflected light the crystals appear dark green, but by transmitted light they appear purple-red.
Anhydrous Ferric(III) chloride is deliquescent, forming hydrated hydrogen chloride mists in moist air.
When dissolved in water, Ferric(III) chloride undergoes hydrolysis and gives off heat in an exothermic reaction.
The resulting brown, acidic, and corrosive solution is used as a coagulant in sewage treatment and drinking water production, and as an etchant for copper-based metals in printed circuit boards.
Anhydrous Ferric(III) chloride is a fairly strong Lewis acid, and it is used as a catalyst in organic synthesis.
Ferric(III) chloride is an industrial-scale metal.
Ferric(III) chloride's formula is FeCl3.
The color of Ferric(III) chloride crystals depends on the viewing angle; with reflected light, the crystals appear dark green, but with transmitted light, they appear purplish-red.
Anhydrous Ferric(III) chloride is soluble, forming hydrogen chloride vapors in humid air.
Ferric(III) chloride is rarely observed in its natural state, mainly in some fumaroles known as molysite.
When dissolved in water, Ferric(III) chloride undergoes hydrolysis and releases heat in an exothermic reaction.
The resulting brown, acidic, and corrosive solution is used as a coagulant in wastewater treatment and drinking water production, and as an etchant for copper-based metals in printed circuit boards.
Anhydrous Ferric(III) chloride is a fairly strong Lewis acid and is used as a catalyst in organic synthesis.
Anhydrous Ferric(III) chloride can be prepared by the combination of the following elements:
2Fe(s) + 3Cl2(g)2 → FeCl3(s)
Ferric(III) chloride solutions are produced industrially, both in closed environments and from iron ore.
From melting iron ore in hydrochloric acid:
Fe3O4(s) + 8 HCl(aqueous) → FeCl2(aq) + 2 FeCl3(aq) + 4H2O(l)
Oxidation of iron(II) chloride with chlorine:
2 FeCl2(aqueous) + Cl2 → 2 FeCl3(g)3(aqueous)
Oxidation of iron(II) chloride with oxygen:
4FeCl2(aqueous) + O2 + 4HCl → 4FeCl3(aq) + 2H2O(l)
Applications of Ferric(III) Chloride:
Ferric(III) chloride is used in sewage and drinking water production.
Ferric(III) chloride is used in anhydrous form as a dry reactant in some reactions.
Ferric(III) chloride is used in organic synthesis to detect the presence of phenolic compounds: e.g., to examine the purity of synthesized Aspirin.
Ferric(III) chloride is used in water and wastewater treatment to precipitate phosphate as iron (III) phosphate.
Ferric(III) chloride has been used by woodworkers and craftsmen as a pattern source to engrave metal, to show the layering or defects of the metal, and to give it a contrasting effect.
Ferric(III) chloride is used to etch the fixture pattern in iron meteorites.
Ferric(III) chloride is used in photogravure for etching, for printing images of photographs and works of art, and as a cylinder used in the gravure printing industry for printing images.
Ferric(III) chloride is used to make printed circuit boards (PCBs).
In veterinary medicine, Ferric(III) chloride is used to treat the mortis of an animal's hoof, especially in cases where bleeding occurs as a result of hemorrhage.
Ferric(III) chloride reacts with cyclopentadienylmagnesium bromide in a preparation of ferrocene, a metal-sandwich complex.
Sometimes used in the Raku trowel firing technique, Ferric(III) chloride colors a piece of iron, pink, brown, and orange.
Ferric(III) chloride is used to test the pit and crevice corrosion resistance of stainless steels and other alloys.
Ferric(III) chloride is used in combination with NaI in acetonitrile to mildly reduce organic azides to primary amines.
Ferric(III) chloride is used in animal thrombosis models.
Ferric(III) chloride is used in energy storage systems.
Historically, Ferric(III) chloride was used to make direct positive plans.
A component of modified Carnoy's solution used in the surgical treatment of keratocystic odontogenic tumor (KOT).
Ferric(III) chloride is used by American coin collectors to determine the dates of Buffalo nicks that are so worn that the date is no longer visible.
Uses of Ferric(III) Chloride:
Ferric(III) chloride is used for sewerage treatment of industrial wastes, chloride hydrometallurgy (Silgarin process for the production of silicon), drinking water production, production of precursor for polyvinyl chloride (PVC), and copper-based metals in printed circuit boards.
Ferric(III) chloride is used as catalyst for the reaction of ethylene with chlorine, as a leaching agent, and as a drying reagent in certain reactions.
Ferric(III) chloride is a mild oxidizing agent and converts copper(I) chloride in to copper(II) chloride.
As a moderately strong Lewis acid, Ferric(III) chloride catalyzes chlorination of aromatic compounds and Friedel-Crafts reactions.
Along with sodium iodide, Ferric(III) chloride brings about reduction of organic azides to corresponding amines.
Ferric(III) chloride is useful in the detection of phenols and phenolic derivatives, gamma-hydroxybutyric acids, and also in Trinder spot test for detecting salicylic acids.
Ferric(III) chloride is used as a medication, an analytical reagent, an etching agent (engraving, photography, and printed circuits), a catalyst, a mordant, a disinfectant, a pigment, and a feed additive.
Ferric(III) chloride is also used in sewage treatment and water purification.
Ferric(III) chloride is found in nature as the mineral molysite; Used in photography, to make other iron salts, pigments, and inks, and for chlorinating silver and copper ores.
Ferric(III) chloride has been used as a surface modulator for the characterization of wines by fingerprinting technology.
Ferric(III) chloride has been used for the quantitative estimation of sulfide in various biological samples.
The vapor-phase co-reductions with other metal halides by hydrogen results in finely divided intermetallics with applications as structural materials or compounds with useful thermoelectric, magnetic, and oxidation-resitance properties.
Industrial:
In industrial application, Ferric(III) chloride is used in sewage treatment and drinking water production.
In this application, FeCl3 in slightly basic water reacts with the hydroxide ion to form a floc of iron(III) hydroxide, or more precisely formulated as FeO(OH)-, that can remove suspended materials.
Fe3+ + 4 OH− → Fe(OH)4− → FeO(OH)2−·H2O
Another important application of Ferric(III) chloride is etching copper in two-step redox reaction to copper(I) chloride and then to copper(II) chloride in the production of printed circuit boards.
FeCl3 + Cu → FeCl2 + CuCl
FeCl3 + CuCl → FeCl2 + CuCl2
Ferric(III) chloride is used as catalyst for the reaction of ethylene with chlorine, forming ethylene dichloride (1,2-dichloroethane), an important commodity chemical, which is mainly used for the industrial production of vinyl chloride, the monomer for making PVC.
H2C=CH2 + Cl2 → ClCH2CH2Cl
Laboratory use:
In the laboratory Ferric(III) chloride is commonly employed as a Lewis acid for catalysing reactions such as chlorination of aromatic compounds and Friedel-Crafts reaction of aromatics.
Ferric(III) chloride is less powerful than aluminium chloride, but in some cases this mildness leads to higher yields, for example in the alkylation of benzene:
The "Ferric(III) chloride test" is a traditional colorimetric test for phenols, which uses a 1% iron(III) chloride solution that has been neutralised with sodium hydroxide until a slight precipitate of FeO(OH) is formed.
The mixture is filtered before use.
The organic substance is dissolved in water, methanol or ethanol, then the neutralised Ferric(III) chloride solution is added—a transient or permanent coloration (usually purple, green or blue) indicates the presence of a phenol or enol.
Other uses:
Anhydrous Ferric(III) chloride is sometimes used as a drying reagent in certain reactions.
Ferric(III) chloride is sometimes used by American coin collectors to identify the dates of Buffalo nickels that are so badly worn that the date is no longer visible.
Ferric(III) chloride is commonly used by knife craftsmen and sword smiths to stain blades, as to give a contrasting effect to the metal, and to view metal layering or imperfections.
Ferric(III) chloride is necessary for the etching of photogravure plates for printing photographic and fine art images in intaglio and for etching rotogravure cylinders used in the printing industry.
Ferric(III) chloride is also used in veterinary practice to treat overcropping of an animal's claws, particularly when the overcropping results in bleeding.
Water treatment:
The largest applications of Ferric(III) chloride are sewage treatment and drinking water production.
By forming highly dispersed networks of Fe-O-Fe containing materials, Ferric(III) chlorides serve as coagulant and flocculants.
In this application, an aqueous solution of FeCl3 is treated with base to form a floc of iron(III) hydroxide (Fe(OH)3), also formulated as FeO(OH) (ferrihydrite).
This floc facilitates the separation of suspended materials, clarifying the water.
Ferric(III) chloride is also used to remove soluble phosphate from wastewater.
Iron(III) phosphate is insoluble and thus precipitates as a solid.
One potential advantage of Ferric(III) chloride's use in water treatment, is that the ferric ion oxidizes (deodorizes) hydrogen sulfide.
Etching and metal cleaning:
Ferric(III) chloride is also used as a leaching agent in chloride hydrometallurgy for example in the production of Si from FeSi.
In another commercial application, a solution of Ferric(III) chloride is useful for etching copper according to the following equation:
2 FeCl3 + Cu → 2 FeCl2 + CuCl2
The soluble copper(II) chloride is rinsed away, leaving a copper pattern.
This chemistry is used in the production of printed circuit boards (PCB).
Ferric(III) chloride is used in many other hobbies involving metallic objects.
Organic chemistry:
In industry, Ferric(III) chloride is used as a catalyst for the reaction of ethylene with chlorine, forming ethylene dichloride (1,2-dichloroethane):
H2C=CH2 + Cl2 → ClCH2CH2Cl
Ethylene dichloride is a commodity chemical, which is mainly used for the industrial production of vinyl chloride, the monomer for making PVC.
Illustrating it use as a Lewis acid, Ferric(III) chloride catalyses electrophilic aromatic substitution and chlorinations.
In this role, Ferric(III) chloride's function is similar to that of aluminium chloride.
In some cases, mixtures of the two are used.
Organic synthesis research:
Although Ferric(III) chlorides are seldom used in practical organic synthesis, they have received considerable attention as reagents because they are inexpensive, earth abundant, and relatively nontoxic.
Many experiments probe both its redox activity and its Lewis acidity.
For example, Ferric(III) chloride oxidizes naphthols to naphthoquinones:
3-Alkylthiophenes are polymerized to polythiophenes upon treatment with Ferric(III) chloride.
Ferric(III) chloride has been shown to promote C-C coupling reaction.
Several reagents have been developed based on supported Ferric(III) chloride.
On silica gel, the anhydrous salt has been applied to certain dehydration and pinacol-type rearrangement reactions.
A similar reagent but moistened induces hydrolysis or epimerization reactions.
On alumina, Ferric(III) chloride has been shown to accelerate ene reactions.
When pretreated with sodium hydride, Ferric(III) chloride gives a hydride reducing agent that convert alkenes and ketones into alkanes and alcohols, respectively.
Histology:
Ferric(III) chloride is a component of useful stains, such as Carnoy's solution, a histological fixative with many applications.
Also, Ferric(III) chloride is used to prepare Verhoeff's stain.
Molecules of Ferric(III) chloride inserted in layers of graphene form GraphExeter, a material developed by the University of Exeter.
Industry Uses:
Other
Plating agent
Processing aids not otherwise specified
Corrosion inhibitor
Not Known or Reasonably Ascertainable
Defoamer
Humectant
Pigment
Etching agent
Chelating agent
Flocculating agent
Solids separation (precipitating) agent, not otherwise specified
Intermediate
Consumer Uses:
Not Known or Reasonably Ascertainable
Flocculating agent
Properties of Ferric(III) Chloride:
Electronic and Optical Properties:
All forms of Ferric(III) chloride are paramagnetic, owing to the presence of unpaired electrons residing in 3d orbitals.
Although Fe(III) chloride can be octahedral or tetrahedral all of these forms have five unpaired electrons, one per d-orbital.
The high spin d5 electronic configuration requires that d-d electronic transitions are spin forbidden, in addition to violating the Laporte rule.
This double forbidden-ness results in its solutions being only pale colored.
Or, stated more technically, the optical transitions are non-intense.
Aqueous ferric sulfate and ferric nitrate, which contain [Fe(H2O)6]3+, are nearly colorless, whereas the chloride solutions are yellow.
Thus, the chloride ligands significantly influence the optical properties of the iron center.
Chemical and Physical Properties:
Ferric(III) chloride has a relatively low melting point and boils at around 315 °C.
The vapour consists of the dimer Fe2Cl6 (compare aluminium chloride) which increasingly dissociates into the monomeric FeCl3 (D3h point group molecular symmetry) at higher temperature, in competition with its reversible decomposition to give iron(II) chloride and chlorine gas.[1]
Reactions:
Ferric(III) chloride is a moderately strong Lewis acid, forming adducts with Lewis bases such as triphenylphosphine oxide, e.g. FeCl3(OPPh3)2 where Ph = phenyl.
Ferric(III) chloride reacts with other chloride salts to give the yellow tetrahedral FeCl4− ion.
Salts of FeCl4− in hydrochloric acid can be extracted into diethyl ether.
When heated with iron(III) oxide at 350 °C, Ferric(III) chloride gives iron oxychloride, a layered solid and intercalation host.
FeCl3 + Fe2O3 → 3 FeOCl
In the presence of base, alkali metal alkoxides react to give the dimeric complexes:
2 FeCl3 + 6 C2H5OH + 6 NH3 → (Fe(OC2H5)3)2 + 6 NH4Cl
Oxalates react rapidly with aqueous Ferric(III) chloride to give [Fe(C2O4)3]3−. Other carboxylate salts form complexes, e.g. citrate and tartrate.
Ferric(III) chloride is a mild oxidising agent, for example capable of oxidising copper(I) chloride to copper(II) chloride.
Reducing agents such as hydrazine convert Ferric(III) chloride to complexes of iron(II).
Structure of Ferric(III) Chloride:
Ferric(III) chloride can exist as an anhydrous material and a series of hydrates, which results in distinct structures.
Anhydrous:
The anhydrous compound is a hygroscopic crystalline solid with a melting point of 307.6 °C.
The colour depends on the viewing angle: by reflected light, the crystals appear dark green, but by transmitted light, they appear purple-red.
Anhydrous Ferric(III) chloride has the BiI3 structure, with octahedral Fe(III) centres interconnected by two-coordinate chloride ligands.
Ferric(III) chloride has a relatively low melting point, and boils at around 315 °C.
The vapor consists of the dimer Fe2Cl6, much like aluminium chloride.
This dimer dissociates into the monomeric FeCl3 (with D3h point group molecular symmetry) at higher temperatures, in competition with its reversible decomposition to give iron(II) chloride and chlorine gas.
Hydrates:
Ferric(III) chloride form hydrates upon exposure to water, reflecting its Lewis acidity.
All hydrates exhibit deliquescence, meaning that they become liquid by absorbing moisture from the air.
Hydration invariably gives derivatives of aquo complexes with the formula [FeCl2(H2O)4]+.
This cation can adopt either trans or cis stereochemistry, reflecting the relative location of the chloride ligands on the octahedral Fe center.
Four hydrates have been characterized by X-ray crystallography: the dihydrate FeCl3·2H2O, the disesquihydrate FeCl3·2.5H2O, the trisesquihydrate FeCl3·3.5H2O, and finally the hexahydrate FeCl3·6H2O.
These species differ with respect to the stereochemistry of the octahedral iron cation, the identity of the anions, and the presence or absence of water of crystallization.
The structural formulas are [trans−FeCl2(H2O)4][FeCl4], [cis−FeCl2(H2O)4][FeCl4]·H2O, [cis−FeCl2(H2O)4][FeCl4]·H2O, and [trans−FeCl2(H2O)4]Cl·2H2O.
The first three members of this series have the tetrahedral tetrachloroferrate ([FeCl4]−) anion.
Solution:
Like the solid hydrates, aqueous solutions of Ferric(III) chloride also consist of the octahedral [FeCl2(H2O)4]+ of unspecified stereochemistry.
Detailed speciation of aqueous solutions of Ferric(III) chloride is challenging because the individual components do not have distinctive spectroscopic signatures.
Iron(III) complexes, with a high spin d5 configuration, are kinetically labile, which means that ligands rapidly dissociate and reassociate.
A further complication is that these solutions are strongly acidic, as expected for aquo complexes of a tricationic metal.
Iron aquo complexes are prone to olation, the formation of polymeric oxo derivatives.
Dilute solutions of Ferric(III) chloride produce soluble nanoparticles with molecular weight of 104, which exhibit the property of "aging", i.e., the structure change or evolve over the course of days.
The polymeric species formed by the hydrolysis of Ferric(III) chlorides are key to the use of Ferric(III) chloride for water treatment.
In contrast to the complicated behavior of its aqueous solutions, solutions of Ferric(III) chloride in diethyl ether and tetrahydrofuran are well-behaved.
Both ethers form 1:2 adducts of the general formula FeCl3(ether)2.
In these complexes, the iron is pentacoordinate.
Preparation of Ferric(III) Chloride:
Several hundred tons of anhydrous Ferric(III) chloride are produced annually.
The principal method, called direct chlorination, uses scrap iron as a precursor:
2 Fe + 3 Cl2 → 2 FeCl3
The reaction is conducted at several hundred degrees such that the product is gaseous.
Using excess chlorine guarantees that the intermediate ferrous chloride is converted to the ferric state.
A similar but laboratory-scale process also has been described.
Aqueous solutions of Ferric(III) chloride are also produced industrially from a number of iron precursors, including iron oxides:
Fe2O3 + 6 HCl + 9 H2O → 2 FeCl3(H2O)6
In complementary route, iron metal can be oxidized by hydrochloric acid followed by chlorination:
Fe + 2 HCl → FeCl2 + H2
FeCl2 + 0.5 Cl2 + 6 H2O → FeCl3(H2O)6
A number of variables apply to these processes, including the oxidation of iron by Ferric(III) chloride and the hydration of intermediates.
Hydrates of Ferric(III) chloride do not readily yield anhydrous ferric chloride.
Attempted thermal dehydration yields hydrochloric acid and iron oxychloride.
In the laboratory, hydrated Ferric(III) chloride can be converted to the anhydrous form by treatment with thionyl chloride or trimethylsilyl chloride:
FeCl3·6H2O + 12 (CH3)3SiCl → FeCl3 + 6 ((CH3)3Si)2O + 12 HCl
FeCl3·6H2O + 6 SOCl2 → FeCl3 + 6 SO2 + 12 HCl
Reactions of Ferric(III) Chloride:
Being high spin d5 electronic configuration Ferric(III) chlorides are labile, meaning that its Cl- and H2O ligands exchange rapidly with free chloride and water.
In contrast to their kinetic lability, Ferric(III) chlorides are thermodynamically robust, as reflected by the vigorous methods applied to their synthesis.
Aside from lability, which applies to anhydrous and hydrated forms, the reactivity of anhydrous ferric chloride reveals two trends:
Ferric(III) chloride is a Lewis acid and an oxidizing agent.
Reactions of anhydrous Ferric(III) chloride reflect its description as both oxophilic and a hard Lewis acid.
Myriad manifestations of the oxophiliicty of Ferric(III) chloride are available.
When heated with iron(III) oxide at 350 °C it reacts to give iron oxychloride:
FeCl3 + Fe2O3 → 3FeOCl
Alkali metal alkoxides react to give the iron(III) alkoxide complexes.
These products have more complicated structures than anhydrous Ferric(III) chloride.
In the solid phase a variety of multinuclear complexes have been described for the nominal stoichiometric reaction between FeCl3 and sodium ethoxide:
FeCl3 + 3 CH3CH2ONa → "Fe(OCH2CH3)3" + 3 NaCl
Ferric(III) chloride forms a 1:2 adduct with Lewis bases such as triphenylphosphine oxide; e.g., FeCl3(OP(C6H5)3)2.
The related 1:2 complex FeCl3(OEt2)2, where Et = C2H5), has been crystallized from ether solution.
Ferric(III) chloride also reacts with tetraethylammonium chloride to give the yellow salt of the tetrachloroferrate ion ((Et4N)[FeCl4]).
Similarly, combining FeCl3 with NaCl and KCl gives Na[FeCl4] and K[FeCl4], respectively.
In addition to these simple stoichiometric reactions, the Lewis acidity of Ferric(III) chloride enables its use in a variety of acid-catalyzed reactions.
In terms of its being an oxidant, Ferric(III) chloride oxidizes iron powder to form iron(II) chloride via a comproportionation reaction:
2 FeCl3 + Fe → 3 FeCl2
A traditional synthesis of anhydrous ferrous chloride is the reduction of FeCl3 with chlorobenzene:
2 FeCl3 + C6H5Cl → 2 FeCl2 + C6H4Cl2 + HCl
Ferric(III) chloride releases chlorine gas when heated above 160 °C, generating ferrous chloride:
2FeCl3 → 2FeCl2 + Cl2
To suppress this reaction, the preparation of Ferric(III) chloride requires an excess of chlorinating agent.
Hydrated FeCl3:
Unlike the anhydrous material, hydrated Ferric(III) chloride is not a particularly strong Lewis acid since water ligands have quenched the Lewis acidity by binding to Fe(III).
Instead, Ferric(III) chloride is a Brønsted-Lowry acid, as the hydrogen atoms on the water ligands become more acidic when the water ligands bond to Fe(III).
Like the anhydrous material, hydrated Ferric(III) chloride is oxophilic.
For example, oxalate salts react rapidly with aqueous Ferric(III) chloride to give [Fe(C2O4)3]3−, known as ferrioxalate.
Other carboxylate sources, e.g., citrate and tartrate, bind as well to give carboxylate complexes.
The affinity of iron(III) for oxygen ligands was the basis of qualitative tests for phenols.
Although superseded by spectroscopic methods, the Ferric(III) chloride test is a traditional colorimetric test.
The affinity of iron(III) for phenols is exploited in the Trinder spot test.
Aqueous Ferric(III) chloride serves as a one-electron oxidant illustrated by its reaction with copper(I) chloride to give copper(II) chloride and iron(II) chloride.
FeCl3 + CuCl → FeCl2 + CuCl2
This fundamental reaction is relevant to the use of Ferric(III) chloride solutions in etching copper.
Organometallic chemistry:
The interaction of anhydrous Ferric(III) chloride with organolithium and organomagnesium compounds has been examined often.
These studies are enabled because of the solubility of FeCl3 in ethereal solvents, which avoids the possibility of hydrolysis of the nucleophilic alkylating agents.
Such studies may be relevant to the mechanism of FeCl3-catalyzed cross-coupling reactions.
The isolation of organoiron(III) intermediates requires low-temperature reactions, lest the [FeR4]− intermediates degrade.
Using methylmagnesium bromide as the alkylation agent, salts of Fe(CH3)4]− have been isolated.
Illustrating the sensitivity of these reactions, methyl lithium LiCH3 reacts with Ferric(III) chloride to give lithium tetrachloroferrate(II) Li2[FeCl4]:
2 FeCl3 + LiCH3 → FeCl2 + Li[FeCl4] + 0.5 CH3CH3
Li[FeCl4] + LiCH3 → Li2[FeCl4] + 0.5 CH3CH3
To a significant extent, iron(III) acetylacetonate and related beta-diketonate complexes are more widely used than FeCl3 as ether-soluble sources of ferric ion.
These diketonate complexes have the advantages that they do not form hydrates, unlike Ferric(III) chloride, and they are more soluble in relevant solvents.
Cyclopentadienyl magnesium bromide undergoes a complex reaction with Ferric(III) chloride, resulting in ferrocene:
3 C5H5MgBr + FeCl3 → Fe(C5H5)2 + 1/n (C5H5)n + 3 MgBrCl
This conversion, although not of practical value, was important in the history of organometallic chemistry where ferrocene is emblematic of the field.
Natural Occurrence of Ferric(III) Chloride:
Like many metal halides, FeCl3 naturally occurs as a trace mineral.
The rare mineral molysite is usually associated with volcanoes and fumaroles.
FeCl3-based aerosol are produced by a reaction between iron-rich dust and hydrochloric acid from sea salt.
This iron salt aerosol causes about 1–5% of naturally occurring oxidization of methane and is thought to have a range of cooling effects; thus, Ferric(III) chloride has been proposed as a catalyst for Atmospheric Methane Removal.[56]
The clouds of Venus are hypothesized to contain approximately 1% FeCl3 dissolved in sulfuric acid.
Stability and Reactivity of Ferric(III) Chloride:
Chemical Stability:
Stable under recommended storage and handling conditions.
Reactivity:
Reacts with bases, reducing agents, and certain metals and may generate heat upon contact with water.
Conditions to Avoid:
Excessive heat, moisture exposure, incompatible materials, and contact with reactive metals.
Incompatible Materials:
Strong bases, reducing agents, alkali metals, and certain reactive metals.
Handling and Storage of Ferric(III) Chloride:
Safe Handling:
Avoid contact with skin, eyes, and clothing and prevent inhalation of dust, mist, or vapors.
Storage Conditions:
Store tightly closed in a cool, dry, well-ventilated area away from moisture and incompatible materials.
First Aid Measures of Ferric(III) Chloride:
Inhalation:
Move the affected person to fresh air and seek medical attention if irritation or breathing difficulty occurs.
Skin Contact:
Immediately wash with plenty of water and remove contaminated clothing.
Eye Contact:
Rinse cautiously with plenty of water for at least 15 minutes and obtain immediate medical attention.
Ingestion:
Rinse mouth, do not induce vomiting, and seek immediate medical attention.
Firefighting Measures of Ferric(III) Chloride:
Suitable Extinguishing Media:
Use extinguishing media appropriate for the surrounding fire.
Specific Hazards:
Ferric(III) chloride is not combustible, but decomposition or reaction may release corrosive or irritating fumes.
Protective Equipment:
Firefighters should wear chemical-resistant protective clothing and self-contained breathing apparatus.
Accidental Release Measures of Ferric(III) Chloride:
Personal Precautions:
Avoid direct contact and inhalation and use suitable protective equipment.
Cleanup Methods:
Carefully collect dry material or absorb liquid spills with inert material and transfer to a corrosion-resistant waste container.
Environmental Precautions:
Prevent significant quantities from entering drains, soil, or surface waters.
Exposure Controls/Personal Protection of Ferric(III) Chloride:
Engineering Controls:
Provide adequate ventilation and suitable eyewash and emergency shower facilities.
Eye Protection:
Wear tightly fitting chemical safety goggles and face protection where splash risk exists.
Hand Protection:
Wear suitable chemical-resistant gloves.
Skin Protection:
Wear appropriate corrosion-resistant protective clothing.
Respiratory Protection:
Use suitable respiratory protection where ventilation is inadequate or dust or mist may be generated.
Identifiers of Ferric(III) Chloride:
Synonym(s): Iron(III) chloride, Ferric chloride, Iron trichloride
Empirical Formula (Hill Notation): Cl3Fe
CAS Number: 7705-08-0
Molecular Weight: 162.20
MDL number: MFCD00011005
EC Index Number: 231-729-4
CAS Number: 7705-08-0, 10025-77-1 (hexahydrate), 54862-84-9 (dihydrate), 64333-00-2 (3.5hydrate)
ChEBI: CHEBI:30808
ChemSpider: 22792
ECHA InfoCard: 100.028.846
EC Number: 231-729-4
PubChem CID: 24380
RTECS number: LJ9100000
UNII: U38V3ZVV3V, 0I2XIN602U (hexahydrate), Y048945596 (dihydrate)
UN number: 1773 (anhydrous), 2582 (aqueous solution)
CompTox Dashboard (EPA): DTXSID8020622
InChI: InChI=1S/3ClH.Fe/h3*1H;/q;;;+3/p-3
Key: RBTARNINKXHZNM-UHFFFAOYSA-K
InChI=1S/3ClH.Fe/h3*1H;/q;;;+3/p-3
Key: RBTARNINKXHZNM-DFZHHIFOAF
Key: RBTARNINKXHZNM-UHFFFAOYSA-K
SMILES: Cl[Fe](Cl)Cl
Linear Formula: FeCl3
CAS Number: 7705-08-0
Molecular Weight: 162.20
NACRES: NA.21
PubChem Substance ID: 329750852
UNSPSC Code: 12352302
EC Number: 231-729-4
MDL number: MFCD00011005
Assay: 97%
Grade: reagent grade
Form: powder
CAS No.: 7705-08-0
Chemical Name: Ferric chloride
CBNumber: CB5444364
Molecular Formula: Cl3Fe Lewis structure
Molecular Weight: 162.2
MDL Number: MFCD00011005
Properties of Ferric(III) Chloride:
Melting point: 304 °C(lit.)
Boiling point: 316 °C
Density: 2,804 g/cm3
bulk density: 1000kg/m3
vapor density: 5.61 (vs air)
vapor pressure: 1 mm Hg ( 194 °C)
refractive index: n20/D1.414
Flash point: 316°C
storage temp.: Store below +30°C.
solubility: H2O: soluble
form: powder
color: Yellow
Specific Gravity: 2.804
PH: 1 (200g/l, H2O, 20℃)
Water Solubility: 920 g/L (20 ºC)
Specific Heat Capacity: Cp(crystal): 0.6 J/(g·K), at 25℃
Crystal Structure: BiI3 type
Sensitive: Hygroscopic
Merck: 14,4019
Chemical formula: FeCl3
Molar mass:
162.204 g/mol (anhydrous)
270.295 g/mol (hexahydrate)
Appearance: Green-black by reflected light; purple-red by transmitted light; yellow solid as hexahydrate; brown as aqueous solution
Odor: Slight HCl
Density:
2.90 g/cm3 (anhydrous)
1.82 g/cm3 (hexahydrate)
Melting point: 307.6 °C (585.7 °F; 580.8 K) (anhydrous)
37 °C (99 °F; 310 K) (hexahydrate)[1]
Boiling point:
316 °C (601 °F; 589 K) (anhydrous, decomposes)
280 °C (536 °F; 553 K) (hexahydrate, decomposes)
Solubility in water: 912 g/L (anhydrous or hexahydrate, 25 °C)
grade: reagent grade
Quality Segment: 200
vapor density: 5.61 (vs air)
vapor pressure: 1 mmHg ( 194 °C)
assay: 97%
form: powder
sustainability: Greener Alternative Product
mp: 304 °C (lit.)
SMILES string: Cl[Fe](Cl)Cl
InChI: 1S/3ClH.Fe/h3*1H;/q;;;+3/p-3
InChI key: RBTARNINKXHZNM-UHFFFAOYSA-K
Appearance: Powder or crystalline powder
Physical State: Solid
Storage: Store at room temperature
Melting Point: 304° C (lit.)
Boiling Point: 531.96° C at 760 mmHg (Predicted)
Density: 2.80 g/cm3
Molecular Weight: 162.20 g/mol
Hydrogen Bond Donor Count: 0
Hydrogen Bond Acceptor Count: 0
Rotatable Bond Count: 0
Exact Mass: 160.841494 Da
Monoisotopic Mass: 160.841494 Da
Topological Polar Surface Area: 0 Ų
Heavy Atom Count: 4
Complexity: 8
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes
Specifications of Ferric(III) Chloride:
Assay: 99 – 102%
Appearance: Yellowish lumps
Substances insoluble in water (H2O): ≤ 0.01%
Iron II (Fe (II)): ≤ 0.002%
Nitrates (NO3): ≤ 0.01%
Phosphate (PO4): ≤ 0.01%
Copper (Cu): ≤ 0.003%
Calcium (Ca): ≤ 0.01%
Sulfates (SO4): ≤ 0.01%
Magnesium (Mg): ≤ 0.005%
Sodium (Na): ≤ 0.05%
Zinc (Zn): ≤ 0.003%
Structure of Ferric(III) Chloride:
Crystal structure: Hexagonal, hR24
Space group: R3, No. 148
Lattice constant: a = 0.6065 nm, b = 0.6065 nm, c = 1.742 nm, α = 90°, β = 90°, γ = 120°
Formula units (Z): 6
Coordination geometry: Octahedral
Related compounds of Ferric(III) Chloride:
Other anions:
Iron(III) fluoride
Iron(III) bromide
Other cations:
Iron(II) chloride
Manganese(II) chloride
Cobalt(II) chloride
Ruthenium(III) chloride
Related coagulants:
Iron(II) sulfate
Polyaluminium chloride
Names of Ferric(III) Chloride:
IUPAC names:
Iron(III) chloride
Iron trichloride
Other names:
Ferric chloride
Molysite
Flores martis
