Vanadyl acetylacetonate
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| Names | |
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IUPAC name
oxobis(2,4-pentanedionato)vanadium(IV)
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| Other names
VO(acac)2, VO(pd)2
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| Identifiers | |
| ECHA InfoCard | 100.019.628 |
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PubChem CID
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| Properties | |
| C10H14O5V | |
| Molar mass | 265.157 g/mol |
| Appearance | blue-green |
| Density | 1.50 g/cm3 |
| Melting point | 258 °C (496 °F; 531 K) |
| Boiling point | 174 °C (345 °F; 447 K) at 0.2 torrs (27 Pa) |
| CHCl3, CH2Cl2, Benzene, CH3OH, CH3CH2OH | |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
Vanadyl acetylacetonate is the chemical compound with the formula VO(acac)2, where acac– is the conjugate base of acetylacetone. It is a blue-green solid that dissolves in polar organic solvents. The coordination complex consists of the vanadyl group, VO2+, bound to two acac– ligands via the two oxygen atoms on each. Like other charge-neutral acetylacetonate complexes, it is not soluble in water.
The complex is generally prepared from vanadium(IV), e.g. vanadyl sulfate:
It can also be prepared by a redox reaction starting with vanadium pentoxide. In this reaction, some acetylacetone is oxidized to acetic anhydride.
The complex has a square pyramidal structure with a short V=O bond. This d1 compound is paramagnetic. Its optical spectrum exhibits two transitions. It is a weak Lewis acid, forming adducts with pyridine and methylamine.
It is used in organic chemistry as a catalyst for the epoxidation of allylic alcohols by tert-butyl hydroperoxide (TBHP). The VO(acac)2–TBHP system exclusively epoxidizes geraniol at the allylic alcohol position, leaving the other alkene of geraniol untouched. By comparison, m-CPBA, another epoxidizing agent, reacts with both alkenes, creating the products in a two to one ratio favoring reaction at the alkene away from the hydroxyl group. TBHP oxidizes VO(acac)2 to a vanadium(V) species which coordinates the alcohol of the substrate and the hydroperoxide.
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