Niklas
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Synthesis of vanadyl acetylacetonate
Alright everyone, hello again.
Today I‘ve once again come to experience the horrors of yellow chem, and had the reactions regarding one of my larger projects turn into a some
shitty tar. So, to get over this pain, I thought of finally doing a simpler, visually appealing inorganic synthesis I‘ve been setting aside for a
while now, making vanadyl acetylacetonate.
Fig.1: Structure of vanadyl acetylacetonate
As my vanadium source I‘m using ammonium metavanadate, which can be converted into the desired product in three steps [1][2].
Fig:2: Synthesis of vanadyl acetylacetonate
All chemicals used in this preparation were purchased from reputable chemical suppliers, primarily Merck and S3-Chemicals.
The first step usually results in quantitative yields, so I didn’t take much effort documenting the exact quantities used of each reagent.
Vanadium(V)-oxide:
To start off a random amount of ammonium metavanadate was added to an erlenmeyer flask and suspended in just enough destilled water to result in a
free flowing slurry. Under constant stirring fuming hydrochloric acid was carefully dripped into the suspension until no more color change could be
observed. The product was finally removed by vacuum filtration, washed with additional destilled water, and dried in a vacuum desiccator. The
vanadium(V)-oxide was collected as a black solid with an metallic shine.
Fig.3: Suspension of ammonium metavandate
Fig.4: Precipitate consisting of vanadium(V)-oxide
Vanadyl sulfate:
0,38 g of the previously prepared vanadium(V)-oxide was suspended in a mixture of 1 ml destilled water, 2 ml absolute ethanol and 0,7 ml of 96%
sulfuric acid. A reflux apparatus was set up and the mixture was heated for 30 minutes, during which time the solid dissolved and a dark blue solution
containing the desired vanadyl sulfate remained. This solution can directly be forwarded to the next step without any isolation of the intermediate.
Fig.5: Suspension of vanadium(V)-oxide
Fig.6: The apparatus used in this preparation
Fig.7: Solution of vanadyl sulfate
Vanadyl acetylacetonate:
To the previous solution of vanadyl sulfate 1 ml of acetylacetone was added, causing the mixture to quickly darken. While stirring, a solution
consisting of 1,6 g of sodium carbonate dissolved in 10 ml of destilled water is prepared, and slowly dripped into the reaction mix. During this time
a teal solid gradually precipitated, which was removed using vacuum filtration and dried in a vacuum desiccator. For further purification the product
was recrystallized from anhydrous chloroform. The vanadyl acetylacetonate was collected as small teal / cerulean crystals.
Fig.8: Precipitate consisting of vanadyl acetylacetonate
Fig.9: Crude vanadyl acetylacetonate collected by vacuum filtration
Fig.10: Recrystallized vanadyl acetylacetonate at 4x magnification
0,705 g ; 63,6% yield, 75-83% in lit. (V2O5->VO(acac)2)
Literature:
[1] https://doi.org/10.1002/9780470132364.ch30
[2] https://patents.google.com/patent/CN109336177B/en
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Pumukli
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Great preparation, nice pictures! I like the colorful chemistry of complexes.
Could you highlight some potential uses of the product? I mean, colorful chemistry is one thing, if you can use your product (as a highly efficient
catalyst e.g.) in an entirely different reaction that is real "coolness"! 
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Niklas
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Quote: Originally posted by Pumukli  | | Could you highlight some potential uses of the product? I mean, colorful chemistry is one thing, if you can use your product (as a highly efficient
catalyst e.g.) in an entirely different reaction that is real "coolness"!
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Oh yeah, absolutely! That’s the reason I love making metal acetylacetonates, they aren’t just beautiful to look at, but actually useful as
affordable catalysts.
Most notably vanadyl acetylacetonate allows for selective epoxidation of allylic alcohols in the presence of t-BuOOH:
There is a bunch more niche applications as well though, some of which can be found on the following page:
https://www.chemicalbook.com/ChemicalProductProperty_EN_CB06...
Personally I‘m particularly interested in its ability to perform asymmetric oxidations of disulfides, which I may make use of in a future project on
making allicin from glycerin:
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EF2000
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Transition metal acetylacetonates are currently studied as catalysts for safer "green" hypergolic rocket propellants, with high test peroxide as
oxidizer. For example, in this paper manganese acetylacetonate is used: https://doi.org/10.1002/prep.201700268
Since hydrogen peroxide is not hypergolic with most "green" fuels, it needs a catalyst. Acetylacetonates has the advantages over inorganic salts: they
are partly combustible and they dissolve well in organic solvents.
Theoretically, vanadyl acetylacetonate should perform a bit better than manganese(II) acac, since V is lighter that Mn (less effect on the specific
impulse). So that cerulean powder can have a celestial application.
If you have a concentrated peroxide, you can (very carefully) test whether it's hypergolic with solution of vanadyl acetylacetonate in ethanol. It's
usually done by dropping a tiny amount of one component into a tiny amount of another.
Edit: attached paper
[Edited on 7-8-2024 by EF2000]
Attachment: Effect of Alcohol Carbon Chain on Enthalpy of Combustion and Ignition Delay.pdf (917kB)
This file has been downloaded 107 times
Wroom wroom
"The practice of pouring yourself alcohol from a rocket fuel tank is to be strongly condemned encouraged"
-R-1 User's Guide
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