Vanadium oxytrichloride is the inorganic compound with the formula VOCl₃. This yellow distillable liquid hydrolyzes readily in air. It is an

oxidizing agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...

. It is used as a reagent in organic synthesis. Samples often appear red or orange owing to an impurity of

vanadium tetrachloride Vanadium tetrachloride is the inorganic compound with the formula V Cl4. This bright red liquid serves as a useful reagent for the preparation of other vanadium compounds. Synthesis, bonding, basic properties With one more valence electron than ...

Properties

VOCl₃ is a vanadium compound with vanadium in the +5 oxidation state and as such is

diamagnetic Diamagnetic materials are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force. In contrast, paramagnetic and ferromagnetic materials are attracted ...

. It is

tetrahedral In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ...

with O-V-Cl bond angles of 111° and Cl-V-Cl bond angles of 108°. The V-O and V-Cl bond lengths are 157 and 214 pm, respectively. VOCl₃ is highly reactive toward water and evolves

HCl HCL may refer to: Science and medicine * Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia * Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development * Hollow-cathode lamp, a spe ...

upon standing. It is soluble in nonpolar solvents such as

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...

, CH₂Cl₂, and

hexane Hexane () is an organic compound, a straight-chain alkane with six carbon atoms and has the molecular formula C6H14. It is a colorless liquid, odorless when pure, and with boiling points approximately . It is widely used as a cheap, relatively ...

. In some aspects, the chemical properties of VOCl₃ and POCl₃ are similar. One distinction is that VOCl₃ is a strong oxidizing agent, whereas the phosphorus compound is not. Neat VOCl₃ is the usual chemical shift standard for ⁵¹V NMR spectroscopy.

Preparation

VOCl₃ arises by the

chlorination Chlorination may refer to: * Chlorination reaction In chemistry, halogenation is a chemical reaction that entails the introduction of one or more halogens into a compound. Halide-containing compounds are pervasive, making this type of transform ...

of V₂O₅. The reaction proceeds near 600 °C: :3 Cl₂ + V₂O₅ → 2 VOCl₃ + 1.5 O₂ Heating an intimate (well-blended with tiny particles) mixture of V₂O₅, chlorine, and

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...

at 200–400 °C also gives VOCl₃. In this case the carbon serves as a

deoxygenation Deoxygenation is a chemical reaction involving the removal of oxygen atoms from a molecule. The term also refers to the removal of molecular oxygen (O2) from gases and solvents, a step in air-free technique and gas purifiers. As applied to orga ...

agent akin to its use in the

chloride process The chloride process is used to separate titanium from its ores. The goal of the process is to win high purity titanium dioxide from ores such as ilmenite (FeTiO3) and rutile (TiO2). The strategy exploits the volatility of TiCl4, which is readily p ...

for the manufacturing of TiCl₄ from TiO₂. Vanadium(III) oxide can also be used as a precursor: :3 Cl₂ + V₂O₃ → 2 VOCl₃ + 0.5 O₂ A more typical laboratory synthesis involves the chlorination of V₂O₅ using SOCl₂. :V₂O₅ + 3 SOCl₂ → 2 VOCl₃ + 3 SO₂

Reactions

Hydrolysis and alcoholysis

VOCl₃ quickly hydrolyzes resulting in

vanadium pentoxide Vanadium(V) oxide (''vanadia'') is the inorganic compound with the formula V2 O5. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because o ...

and

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

. In the picture, orange V₂O₅ can be seen forming on the walls of the beaker. An intermediate in this process is VO₂Cl: :2 VOCl₃ + 3 H₂O → V₂O₅ + 6 HCl VOCl₃ reacts with alcohols especially in the presence of a proton-acceptor to give alkoxides, as illustrated by this synthesis of

vanadyl isopropoxide Vanadyl isopropoxide is the metal alkoxide with the formula VO(O-iPr)3 (iPr = CH(CH3)2). A yellow volatile liquid, it is a common alkoxide of vanadium. It is used as a reagent and as a precursor to vanadium oxides. The compound is diamagnetic. It ...

: :VOCl₃ + 3 HOCH(CH₃)₂ → VO(OCH(CH₃)₂)₃ + 3 HCl

Interconversions to other V-O-Cl compounds

VOCl₃ is also used in the synthesis of

vanadium oxydichloride Vanadium oxydichloride is the inorganic compound with the formula VOCl2. One of several oxychlorides of vanadium, it is a hygroscopic green solid. It is prepared by comproportionation of vanadium trichloride and vanadium(V) oxides: :V2O5 + VO ...

. :V₂O₅ + 3 VCl₃ + VOCl₃ → 6 VOCl₂ VO₂Cl can be prepared by an unusual reaction involving Cl₂O. :VOCl₃ + Cl₂O → VO₂Cl + 2 Cl₂ At >180 °C, VO₂Cl decomposes to V₂O₅ and VOCl₃. Similarly, VOCl₂ also decomposes to give VOCl₃, together with VOCl.

Adduct formation

VOCl₃ is strongly Lewis acidic, as demonstrated by its tendency to form

adduct An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...

s with various bases such as acetonitrile and

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen Hydrogen is the chemical element wi ...

s. In forming the adducts, vanadium changes from four-coordinate tetrahedral geometry to six-coordinate octahedral geometry: :VOCl₃ + 2 H₂NEt → VOCl₃(H₂NEt)₂

VOCl₃ in alkene polymerization

VOCl₃ is used as a catalyst or precatalyst in production of ethylene-propylene rubbers (EPDM).

References

{{Vanadium compounds Vanadium(V) compounds Oxychlorides Metal halides Vanadyl compounds