Vanadium oxytrichloride

Vanadium oxytrichloride is the inorganic compound with the formula VOCl3. This yellow distillable liquid hydrolyzes readily in air. It is an oxidizing agent. It is used as a reagent in organic synthesis.[1] Samples often appear red or orange owing to an impurity of vanadium tetrachloride.[2]

Vanadium oxytrichloride
Names
IUPAC name
Vanadium trichloride oxide
Other names
  • Vanadyl chloride
  • Vanadyl trichloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.892
EC Number
  • 231-780-2
MeSH trichlorooxo+vanadium
RTECS number
  • YW2975000
UNII
UN number 2443
Properties
VOCl
3
Molar mass 173.300 g mol−1
Appearance yellow 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)
Decomposes
Vapor pressure 1.84 kPa (at 20 °C)
Structure
Tetrahedral
Hazards
GHS pictograms
GHS Signal word Danger
H301, H314
P280, P301+310, P305+351+338, P310
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity 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. hydrogen peroxideSpecial hazards (white): no code
1
3
3
Lethal dose or concentration (LD, LC):
140 mg kg−1 (oral, rat)
Related compounds
Related vanadiums
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Properties

VOCl3 is a vanadium compound with vanadium in the +5 oxidation state 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.[3] Neat VOCl3 is the usual chemical shift standard for 51V NMR spectroscopy.[4]

Preparation

VOCl3 arises by the chlorination of V2O5. The reaction proceeds near 600 °C:[5]

3 Cl2 + V2O5 → 2 VOCl3 + 1.5 O2

Heating an intimate (well-blended with tiny particles) mixture of V2O5, chlorine, and carbon at 200–400 °C also gives VOCl3. In this case the carbon serves as a deoxygenation agent akin to its use in the chloride process for the manufacturing of TiCl4 from TiO2.

Vanadium(III) oxide can also be used as a precursor:[2]

3 Cl2 + V2O3 → 2 VOCl3 + 0.5 O2

A more typical laboratory synthesis involves the chlorination of V2O5 using SOCl2.[6]

V2O5 + 3 SOCl2 → 2 VOCl3 + 3 SO2

Reactions

Hydrolysis and alcoholysis

VOCl3 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 to give alkoxides, as illustrated by this synthesis of vanadyl isopropoxide:

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.

V2O5 + 3 VCl3 + VOCl3 → 6 VOCl2

VO2Cl can be prepared by an unusual reaction involving Cl2O.[7]

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 adducts with various bases such as acetonitrile 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

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

References
  1. O'Brien, Michael K.; Vanasse, Benoit (2001). "Vanadyl Trichloride". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rv004. ISBN 0471936235.
  2. F. E. Brown, F. A. Griffitts (1939). "Hypovanadous Oxide and Vanadium Oxytrichloride". Inorganic Syntheses. Inorg. Synth. Inorganic Syntheses. I. pp. 106–108. doi:10.1002/9780470132326.ch38. ISBN 9780470132326.CS1 maint: uses authors parameter (link)
  3. A. Earnshaw, N. Greenwood (1997). The Chemistry of the Elements - Second Edition. pp. 513–514.
  4. Rehder, D.; Polenova, T.; Bühl, M. (2007). Vanadium-51 NMR. Annual Reports on NMR Spectroscopy. 62. pp. 49–114. doi:10.1016/S0066-4103(07)62002-X. ISBN 9780123739193.
  5. Holleman, Arnold Frederik; Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry. Academic Press. ISBN 9780123526519.
  6. G. Brauer "Vanadium oxytrichloride" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1264.
  7. 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.
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