Vanadium oxytrichloride
From Wikipedia, the free encyclopedia
| Vanadium oxytrichloride | |
|---|---|
 |
|
| General | |
| Systematic name | Vanadium(V) oxide trichloride |
| Other names | Vanadium oxytrichloride Vanadyl chloride Vanadyl trichloride |
| Molecular formula | VOCl3 |
| SMILES | VOClClCl |
| Molar mass | 173.30 g/mol |
| Appearance | Yellow to brown liquid |
| CAS number | [7727-18-6] |
| Properties | |
| Density and phase | 1.84 g/cm3, liquid |
| Solubility in water | Decomposes |
| Other solvents | chlorinated solvents |
| Melting point | -76.5 °C |
| Boiling point | 126–127 °C (400 K) |
| Viscosity | ? cP at ? °C |
| Structure | |
| Molecular shape | Tetrahedral |
| Dipole moment | ? D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | Toxic, hydrolysis to HCl |
| NFPA 704 |
1
3
3
|
| R/S statement | R: R14 R25 R34 S: S26 S27 S28 S36/37/39 S45 |
| RTECS number | YW2975000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related vanadium compounds |
Vanadium(V) oxide Vanadium tetrachloride Vanadium oxytrifluoride |
| Related compounds | Phosphorus oxytrichloride |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
Vanadium oxytrichloride is VOCl3. It is a distillable liquid, which hydrolyzes readily in air (see picture). VOCl3 is a vanadium(V) compound and as such 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 1.57 and 2.14 Å, respectively.
Contents |
[edit] Properties
VOCl3 is highly reactive toward water and evolves Cl2 upon standing. Although VOCl3 reacts with hydroxylic solvents (see below), it is soluble in hydrocarbons such as benzene, CH2Cl2, and hexane.
In many aspects, the chemical properties of VOCl3 and POCl3 are similarly shaped molecular compounds. One distinction is that VOCl3 is a strong oxidizing agent, whereas the phosphorus compound is not.
[edit] Preparation
VOCl3 is synthesized by the chlorination of V2O5. 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, 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:
-
- 3 Cl2 + V2O3 → 2 VOCl3 + 0.5 O2
A more typical laboratory synthesis entails chlorination of V2O5 using SOCl2.
-
- V2O5 + 3 SOCl2 → 2 VOCl3 + 3 SO2
[edit] Reactions
[edit] Hydrolysis and alcoholysis
Vanadium oxytrichloride quickly hydrolyzes resulting in vanadium pentoxide 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:
- 2 VOCl3 + 3 H2O → V2O5 + 6 HCl
VOCl3 react with alcohols especially in the presence of a proton-acceptor (e.g. Et3N) to give esters
-
- VOCl3 + 3 ROH → VO(OR)3 + 3 HCl (R = Me, Ph, etc.)
[edit] 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.
[edit] Adduct formation
VOCl3 is strongly Lewis acidic, 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
[edit] Oxidation reactions
The oxidizing power of VOCl3 is exploited in its use for the oxidative coupling of phenols as well as oxidative decarboxylations and deoxygenations.
[edit] VOCl3 in alkene polymerization
VOCl3 is used as a catalyst or precatalytst in production of ethylene-propylene rubbers (EPDM).
[edit] References
- A. Earnshaw, N. Greenwood (1997). The Chemistry of the Elements - Second Edition.
- M. O'Brien, B. Vanasse (2001). Encyclopedia of Reagents for Organic Synthesis.
- A. Holleman, E. Wiberg (2001). Inorganic Chemistry.
- S. Tyree (1967). Inorganic Syntheses Volume IX.
- H. Oppermann, "Gleichgewichte mit VOCl3, VO2Cl, VOCl2" Zeitschrift für Anorganische und Allgemeine Chemie, vol. 331. 113-126 (1967)
