Vanadium oxytrichloride

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Vanadium oxytrichloride
Ball and stick model of vanadium oxytrichloride
Sample of vanadium oxytrichloride in a beaker
Identifiers
CAS number 7727-18-6 YesY
ChemSpider 10613097 N
EC number 231-780-2
UN number 2443
MeSH trichlorooxo+vanadium
RTECS number YW2975000
Jmol-3D images Image 1
Properties
Molecular formula VOCl
3
Molar mass 173.300 g mol−1
Appearance Vivid orange, transparent liquid
Density 1.826 g mL−1
Melting point −76.5 °C (−105.7 °F; 196.7 K)
Boiling point 126.7 °C (260.1 °F; 399.8 K)
Solubility in water Decomposes
Vapor pressure 1.84 kPa (at 20 °C)
Structure
Molecular shape Tetrahedral
Hazards
GHS pictograms The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The skull-and-crossbones pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H301, H314
GHS precautionary statements P280, P301+310, P305+351+338, P310
EU classification Toxic T
R-phrases R14, R25, R34
S-phrases S26, S27, S36/37/39, S45
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g., fluorine Special hazards (white): no codeNFPA 704 four-colored diamond
LD50 140 mg kg−1 (oral, rat)
Related compounds
Related vanadiums
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

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.[1]

Properties[edit]

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 HCl 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.[2]

Preparation[edit]

VOCl3 is synthesized by the chlorination of V2O5. The reaction proceeds at c. 600 °C:[3]

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 involves the chlorination of V2O5 using SOCl2.[4]

V2O5 + 3 SOCl2 → 2 VOCl3 + 3 SO2

Reactions[edit]

Hydrolysis and alcoholysis[edit]

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 reacts with alcohols especially in the presence of a proton-acceptor (e.g. Et3N) to give alkoxides:

VOCl3 + 3 ROH → VO(OR)3 + 3 HCl (R = Me, Ph, etc.)

Interconversions to other V-O-Cl compounds[edit]

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.[5]

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[edit]

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

VOCl3 in alkene polymerization[edit]

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

References[edit]

  1. ^ M. O'Brien, B. Vanasse (2001). Encyclopedia of Reagents for Organic Synthesis. 
  2. ^ A. Earnshaw, N. Greenwood (1997). The Chemistry of the Elements - Second Edition. pp. 513–514. 
  3. ^ A. Holleman, E. Wiberg (2001). Inorganic Chemistry. 
  4. ^ S. Tyree (1967). Inorganic Syntheses Volume IX. p. 80. 
  5. ^ Oppermann, H. (1967). "Untersuchungen an Vanadinoxidchloriden und Vanadinchloriden. I. Gleichgewichte mit VOCl3, VO2Cl und VOCl2". Zeitschrift für anorganische und allgemeine Chemie 351 (3-4): 113–126. doi:10.1002/zaac.19673510302.