Titanium tetrachloride
Overview
 
Titanium tetrachloride is the inorganic compound
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 TiCl4. It is an important intermediate in the production of titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

 metal and the pigment titanium dioxide
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...

. TiCl4 is an unusual example of a metal halide that is highly volatile
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

. Upon contact with humid air, it forms spectacular opaque clouds of titanium dioxide
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...

 (TiO2) and hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...

 (HCl).
TiCl4 is a dense, colourless distillable
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

 liquid, although crude samples may be yellow or even red-brown.
Encyclopedia
Titanium tetrachloride is the inorganic compound
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 TiCl4. It is an important intermediate in the production of titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

 metal and the pigment titanium dioxide
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...

. TiCl4 is an unusual example of a metal halide that is highly volatile
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

. Upon contact with humid air, it forms spectacular opaque clouds of titanium dioxide
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...

 (TiO2) and hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...

 (HCl).

Properties and structure

TiCl4 is a dense, colourless distillable
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

 liquid, although crude samples may be yellow or even red-brown. It is one of the rare transition metal halides that is a liquid at room temperature, VCl4
Vanadium tetrachloride
Vanadium tetrachloride is the inorganic compound with the formula VCl4. This bright red liquid is a useful reagent for the preparation of other vanadium compounds.-Synthesis, bonding, basic properties:...

 being another example. This property reflects the fact that TiCl4 is molecular; that is, each TiCl4 molecule is relatively weakly associated with its neighbours. Most metal chlorides are polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

s, wherein the chloride atoms bridge between the metals. The attraction between the individual TiCl4 molecules is weak, primarily van der Waals forces, and these weak interactions result in low melting
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...

 and boiling point
Boiling point
The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid....

s, similar to those of CCl4
CCL4
Chemokine ligand 4, also known as CCL4, is a protein which in humans is encoded by the CCL4 gene.- Function :CCL4, also known as Macrophage inflammatory protein-1β is a CC chemokine with specificity for CCR5 receptors...

.

Ti4+ has a "closed" electronic shell, with the same number of electrons as the inert gas
Inert gas
An inert gas is a non-reactive gas used during chemical synthesis, chemical analysis, or preservation of reactive materials. Inert gases are selected for specific settings for which they are functionally inert since the cost of the gas and the cost of purifying the gas are usually a consideration...

 argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...

. The tetrahedral structure for TiCl4 is consistent with its description as a d0 metal center (Ti4+) surrounded by four identical ligands. This configuration leads to highly symmetrical
Symmetry
Symmetry generally conveys two primary meanings. The first is an imprecise sense of harmonious or aesthetically pleasing proportionality and balance; such that it reflects beauty or perfection...

 structures, hence the tetrahedral shape of the molecule. TiCl4 adopts similar structures to TiBr4
Titanium tetrabromide
Titanium tetrabromide is the chemical compound with the formula TiBr4. It is the most volatile transition metal bromide. The properties of TiBr4 are an average of TiCl4 and TiI4. Some key properties of these four-coordinated Ti species are their high Lewis acidity and their high solubility in...

 and TiI4
Titanium tetraiodide
Titanium tetraiodide is an inorganic compound with the formula TiI4. It is a rare molecular binary metal iodide, consisting of isolated molecules of tetrahedral Ti centers. Reflecting its molecular character, TiI4 can be distilled without decomposition at one atmosphere; this property is the...

; the three compounds share many similarities. TiCl4 and TiBr4 react to give mixed halides TiCl4-xBrx, where x = 0, 1, 2, 3, 4. Magnetic resonance measurements also indicate that halide exchange is also rapid between TiCl4 and VCl4.

TiCl4 is soluble in toluene
Toluene
Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...

 and chlorocarbons, as are other non-polar
Chemical polarity
In chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in...

 species. Evidence exists that certain arene
Arene
Arene or Arênê or Arène may refer to:*an aromatic hydrocarbon*Arene , a genus of marine snails in the family Areneidae*Arene , the wife of Aphareus and mother of Idas and Lynceus in Greek mythology...

s form complexes of the type [(C6R6)TiCl3]+. TiCl4 reacts exothermic
Exothermic
In thermodynamics, the term exothermic describes a process or reaction that releases energy from the system, usually in the form of heat, but also in the form of light , electricity , or sound...

ally with donor solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...

s such as THF
ThF
Follicular B helper T cells , are antigen-experienced CD4+ T cells found in the B cell follicles of secondary lymphoid organs such as lymph nodes, spleens and Peyer's patches, and are identified by their constitutive expression of the B cell follicle homing receptor CXCR5...

 to give hexacoordinated adduct
Adduct
An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species...

s. Bulkier ligand
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...

s (L) give pentacoordinated adduct
Adduct
An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species...

s TiCl4L.

Production

TiCl4 is produced by the chloride process
Chloride process
The chloride process is used to separate titanium from its ores. In this process, the feedstock is chlorinated at 1000 °C with carbon and chlorine gas, giving titanium tetrachloride...

, which involves the reduction
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

 of titanium oxide ores, typically ilmenite
Ilmenite
Ilmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-gray. It is a crystalline iron titanium oxide . It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite....

 (FeTiO3) with carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 under flowing chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 at 900 °C. Impurities are removed by distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

.
2 FeTiO3 + 7 Cl2 + 6 C → 2 TiCl4 + 2 FeCl3 + 6 CO


The coproduction of FeCl3
Iron(III) chloride
Iron chloride, also called ferric chloride, is an industrial scale commodity chemical compound, with the formula FeCl3. The colour of iron chloride crystals depends on the viewing angle: by reflected light the crystals appear dark green, but by transmitted light they appear purple-red...

 is undesirable, which has motivated the development of alternative technologies. Instead of directly using ilmenite, "rutile slag" is used. This material, an impure form of TiO2, is derived from ilmenite by removal of iron, either using carbon reduction or extraction with sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

. Crude TiCl4 contains a variety of other volatile halides, including vanadyl chloride (VOCl3), silicon tetrachloride
Silicon tetrachloride
Silicon tetrachloride is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications.-Preparation:...

 (SiCl4), and tin tetrachloride (SnCl4), which must be separated.

Production of titanium metal

The world's supply of titanium metal, about 4M tons per year, is made from TiCl4. The conversion takes place by the reduction of the chloride with magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

 metal, and yields titanium metal and magnesium chloride
Magnesium chloride
Magnesium chloride is the name for the chemical compounds with the formulas MgCl2 and its various hydrates MgCl2x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine or sea water...

. This procedure is the final step of the Kroll process
Kroll process
Kroll Process is a pyrometallurgical industrial process used to produce metallic titanium. It was invented by William J. Kroll in Luxembourg. After moving to the United States, Kroll further developed the method for the production of zirconium...

:
2 Mg + TiCl4 → 2 MgCl2 + Ti


Liquid sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

 has also been used instead of magnesium as the reducing agent
Reducing agent
A reducing agent is the element or compound in a reduction-oxidation reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized"...

.

Production of titanium dioxide

Around 90% of the TiCl4 production is used to make the pigment titanium dioxide
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...

 (TiO2). The conversion involves hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

 of TiCl4, a process that forms hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...

:
TiCl4 + 2 H2O → TiO2 + 4 HCl


In some cases, TiCl4 is oxidised directly with oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

:
TiCl4 + O2 → TiO2 + 2 Cl2

Chemical reactions

Titanium tetrachloride is a versatile reagent that forms diverse derivatives including those illustrated below.

Hydrolysis and related reactions

The most noteworthy reaction of TiCl4 is its easy hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

, signaled by the release of corrosive hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...

 and the formation of titanium oxide
Titanium oxide
Titanium oxide may refer to:* Titanium dioxide , TiO2* Titanium oxide , TiO, a non-stoichiometric oxide* Titanium oxide , Ti2O3* Ti3O* Ti2O* δ-TiOx...

s and oxychlorides, as described above for the production of TiO2. In the past titanium tetrachloride has also been used to create naval smokescreens
Smoke-screen
thumb|right|205px|A [[U.S. Army]] [[Humvee]] laying a smoke screenA smoke screen is smoke released to mask the movement or location of military units such as infantry, tanks, aircraft or ships....

. The hydrogen chloride immediately absorbs more water to form tiny droplets of hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

, which (depending on humidity) may absorb still more water, to produce large droplets that efficiently scatter light. In addition, the highly refractive titanium dioxide is also an efficient light scatterer. Because of the corrosiveness of its smoke, however, TiCl4 is no longer used.

Alcohols react with TiCl4 to give the corresponding alkoxides with the formula [Ti(OR)4]n (R = alkyl, n = 1, 2, 4). As indicated by their formula, these alkoxide
Alkoxide
An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO−, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands...

s can adopt complex structures ranging from monomers to tetramers. Such compounds are useful in materials science
Materials science
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...

 as well as organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

. A well known derivative is titanium isopropoxide, which is a monomer.

Organic amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

s react with TiCl4 to give complexes containing amido (R2N--containing) and imido (RN2--containing) complexes. With ammonia, titanium nitride
Titanium nitride
Titanium nitride is an extremely hard ceramic material, often used as a coating on titanium alloys, steel, carbide, and aluminium components to improve the substrate's surface properties....

 is formed. An illustrative reaction is the synthesis of tetrakis(dimethylamido)titanium Ti(NMe2)4, a yellow, benzene-soluble liquid: This molecule is tetrahedral, with planar nitrogen centers.
4 LiNMe2 + TiCl4 → 4 LiCl + Ti(NMe2)4

Complexes with simple ligands

TiCl4 is a Lewis acid
Lewis acid
]The term Lewis acid refers to a definition of acid published by Gilbert N. Lewis in 1923, specifically: An acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. Thus, H+ is a Lewis acid, since it can accept a lone pair,...

 as implicated by its tendency to hydrolyze
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

. With the ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...

 THF, TiCl4 reacts to give yellow crystals of TiCl4(THF)2. With chloride salts, TiCl4 reacts to form sequentially [Ti2Cl9], [Ti2Cl10]2− (see figure above), and [TiCl6]2−. Interestingly, the reaction of chloride ions with TiCl4 depends on the counterion. NBu4Cl and TiCl4 gives the pentacoordinate complex NBu4TiCl5, whereas smaller NEt4+ gives (NEt4)2Ti2Cl10. These reactions highlight the influence of electrostatic forces on the structures of compounds with highly ionic bonding.

Redox

Reduction of TiCl4 with aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 results in one-electron reduction. The trichloride (TiCl3) and tetrachloride have contrasting properties: the trichloride is a solid, being a coordination polymer, and is paramagnetic. When the reduction is conducted in THF
Tetrahydrofuran
Tetrahydrofuran is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. This heterocyclic compound has the chemical formula 4O. As one of the most polar ethers with a wide liquid range, it is a useful solvent. Its main use, however, is as a precursor...

 solution, the Ti(III) product converts to the light-blue adduct TiCl3(thf)3.

Organometallic chemistry

The organometallic chemistry
Organometallic chemistry
Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character...

 of titanium typically starts from TiCl4. An important reaction involves sodium cyclopentadienyl
Cyclopentadiene
Cyclopentadiene is an organic compound with the formula C5H6. This colorless liquid has a strong and unpleasant odor. At room temperature, this cyclic diene dimerizes over the course of hours to give dicyclopentadiene via a Diels–Alder reaction...

 to give titanocene dichloride
Titanocene dichloride
Titanocene dichloride is the organotitanium compound with the formula 2TiCl2, commonly abbreviated as Cp2TiCl2. This metallocene is a common reagent in organometallic and organic synthesis. It exists as a bright red solid that slowly hydrolyzes in air...

, TiCl2(C5H5)2. This compound and many of its derivatives are precursors to Ziegler-Natta catalyst
Ziegler-Natta catalyst
A Ziegler–Natta catalyst is a catalyst used in the synthesis of polymers of 1-alkenes . Three types of Ziegler–Natta catalysts are currently employed:* Solid and supported catalysts based on titanium compounds...

s. Tebbe's reagent
Tebbe's reagent
The Tebbe reagent is the organometallic compound with the formula 2TiCH2ClAl2. It used in the methylenation of carbonyl compounds, that is it converts organic compounds containing the R2C=O group into the related R2C=CH2 derivative...

, useful in organic chemistry, is an aluminium-containing derivative of titanocene that arises from the reaction of titanocene dichloride with trimethylaluminium
Trimethylaluminium
Trimethylaluminium is the chemical compound with the formula Al26, abbreviated as Al2Me6, 2 or the abbreviation TMA. This pyrophoric, colorless liquid is an industrially important organoaluminium compound...

. It is used for the "olefination" reactions.

Arene
Arene
Arene or Arênê or Arène may refer to:*an aromatic hydrocarbon*Arene , a genus of marine snails in the family Areneidae*Arene , the wife of Aphareus and mother of Idas and Lynceus in Greek mythology...

s, such as C6(CH3)6 react to give the piano-stool complexes [Ti(C6R6)Cl3]+ (R = H, CH3; see figure above). This reaction illustrates the high Lewis acidity of the TiCl3+ entity, which is generated by abstraction of chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

 from TiCl4 by AlCl3.

Reagent in organic synthesis

TiCl4 finds limited but diverse use in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

, capitalizing on its Lewis acid
Lewis acid
]The term Lewis acid refers to a definition of acid published by Gilbert N. Lewis in 1923, specifically: An acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. Thus, H+ is a Lewis acid, since it can accept a lone pair,...

ity and its oxophilicity. Illustrative is the Mukaiyama aldol reaction. Key to this application is the tendency of TiCl4 to activate aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

s (RCHO) by formation of adduct
Adduct
An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species...

s such (RCHO)TiCl4OC(H)R. It is also used in the McMurry reaction
McMurry reaction
The McMurry reaction is an organic reaction in which two ketone or aldehyde groups are coupled to an alkene using titanium chloride compound such as titanium chloride and a reducing agent. The reaction is named after its co-discoverer, John E. McMurry. The McMurry reaction originally involved the...

 in conjunction with zinc, LiAlH4
Lithium aluminium hydride
Lithium aluminium hydride, commonly abbreviated to LAH or known as LithAl, is an inorganic compound with the chemical formula LiAlH4. It was discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters,...

. These reducing agents generate Ti(III) derivatives that couple ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

s, leading to alkenes.

Toxicity and safety considerations

Hazards posed by titanium tetrachloride generally arise from the release of hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...

 (HCl). TiCl4 is a strong Lewis acid
Lewis acid
]The term Lewis acid refers to a definition of acid published by Gilbert N. Lewis in 1923, specifically: An acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. Thus, H+ is a Lewis acid, since it can accept a lone pair,...

, exothermically forming adducts with even weak bases such as THF
ThF
Follicular B helper T cells , are antigen-experienced CD4+ T cells found in the B cell follicles of secondary lymphoid organs such as lymph nodes, spleens and Peyer's patches, and are identified by their constitutive expression of the B cell follicle homing receptor CXCR5...

and explosively with water, releasing HCl.

General reading

  • Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.

External links

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