Vanadium oxytrichloride
Encyclopedia
Vanadium oxytrichloride is the inorganic compound
with the formula
VOCl3. This distillable liquid hydrolyzes readily in air and is a strong oxidant. It is used as a reagent
in organic synthesis
.
upon standing. It is soluble in nonpolar solvents such as benzene
, CH2Cl2, and hexane
. 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.
. The reaction proceeds at ca. 600 °C:
When the V2O5 is used as an intimate mixture with carbon
, the synthesis proceeds at 200-400 °C; in this case the carbon serves as a deoxygenation agent akin to its use in the Kroll process
for the manufacturing of TiCl4
from TiO2
.
Vanadium(III) oxide can also be used as a precursor:
A more typical laboratory synthesis involves the chlorination of V2O5 using SOCl2
.
and hydrochloric acid
. In the picture, orange V2O5 can be seen forming on the walls of the beaker. An intermediate in this process is VO2Cl:
VOCl3 reacts with alcohols especially in the presence of a proton-acceptor (e.g. Et3N) to give alkoxide
s:
Dioxovanadium monochloride can be prepared by an unusual reaction involving Cl2O.
At >180 °C, VO2Cl decomposes to V2O5 and VOCl3.
Similarly, VOCl2 also decomposes to give VOCl3, together with VOCl.
ic, as demonstrated by its tendency to form adducts with various bases such as MeCN and amines. In forming the adducts, vanadium changes from four-coordinate tetrahedral geometry to six-coordinate octahedral geometry:
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....
VOCl3. This distillable liquid hydrolyzes readily in air and is a strong oxidant. It is used as a reagent
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
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...
.
Properties
VOCl3 is a vanadium(V) compound and as such is diamagnetic. It is tetrahedral 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 Cl2Chlorine
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...
upon standing. It is soluble in nonpolar solvents such as benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
, CH2Cl2, and hexane
Hexane
Hexane is a hydrocarbon with the chemical formula C6H14; that is, an alkane with six carbon atoms.The term may refer to any of four other structural isomers with that formula, or to a mixture of them. In the IUPAC nomenclature, however, hexane is the unbranched isomer ; the other four structures...
. In some aspects, the chemical properties of VOCl3 and POCl3 are similar. One distinction is that VOCl3 is a strong oxidizing agent
Oxidizing agent
An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...
, whereas the phosphorus compound is not.
Preparation
VOCl3 is synthesized by the chlorination of V2O5Vanadium(V) oxide
Vanadium oxide is the chemical compound with the formula V2O5. Commonly known as vanadium pentoxide, this brown/yellow solid is the most stable and common compound of vanadium. Upon heating it reversibly loses oxygen...
. The reaction proceeds at ca. 600 °C:
- 3 Cl2 + V2O5 → 2 VOCl3 + 1.5 O2
When the V2O5 is used as an intimate mixture 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...
, the synthesis proceeds at 200-400 °C; in this case the carbon serves as a deoxygenation agent akin to its use in 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...
for the manufacturing of TiCl4
Titanium tetrachloride
Titanium tetrachloride is the inorganic compound with the formula TiCl4. It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. TiCl4 is an unusual example of a metal halide that is highly volatile...
from TiO2
Titanium oxide
Titanium oxide may refer to:* Titanium dioxide , TiO2* Titanium oxide , TiO, a non-stoichiometric oxide* Titanium oxide , Ti2O3* Ti3O* Ti2O* δ-TiOx...
.
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
Thionyl chloride
Thionyl chloride is an inorganic compound with the formula SOCl2. It is a reactive chemical reagent used in chlorination reactions. It is a colorless, distillable liquid at room temperature and pressure that decomposes above 140 °C. Thionyl chloride is sometimes confused with sulfuryl...
.
- V2O5 + 3 SOCl2 → 2 VOCl3 + 3 SO2
Hydrolysis and alcoholysis
Vanadium oxytrichloride quickly hydrolyzes resulting in vanadium pentoxideVanadium(V) oxide
Vanadium oxide is the chemical compound with the formula V2O5. Commonly known as vanadium pentoxide, this brown/yellow solid is the most stable and common compound of vanadium. Upon heating it reversibly loses oxygen...
and 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....
. 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 (e.g. Et3N) to give 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:
- VOCl3 + 3 ROH → VO(OR)3 + 3 HCl (R = Me, Ph, etc.)
Interconversions to other V-O-Cl compounds
VOCl3 is also used in the synthesis of VOCl2.- V2O5 + 3 VCl3 + VOCl3 → 6 VOCl2
Dioxovanadium monochloride 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 acidLewis 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,...
ic, as demonstrated by its tendency to form adducts with various bases such as MeCN and amines. In forming the adducts, vanadium changes from four-coordinate tetrahedral geometry to six-coordinate octahedral geometry:
- VOCl3 + 2 H2NEt → VOCl3(H2NEt)2