Axt
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Vanadium Oxytrinitrate
Im looking for information on VO(NO3)3, there is a listing in Fedoroff which I have included, its properties seem interesting. I haven't been able to
access any of the references given. The full references for those given in Fedoroff are below for those interested and may have access to them:
<font size="1">
<center><img src="http://www.sciencemadness.org/scipics/axt/vonitrate.jpg"></center>
1) Gmelin, Syst No 48, Teil A & Teil B (Lieferung 1 & 2) (1967); Teil A (Lieferung 1) & Teil A (Lieferung 2) (1968);& Erganzungwerk
(Band2)(1971)
4) M. Schmeisser, "Angewandre Chemie", (1955) 67, pg. 495 and 499 & "Chemical Abstracts", (1955), 49, 10873
19) L. Bretherick, Ed, “Hazards in the Chemical Laboratory”, Royal Society of Chemistry, London,
Engl (1979), pg. 1160</font>
Im particularly interested in the HNO3/V2O5/C2H2O4 route.
My Experimental: 17% nitric acid was saturated with oxalic acid at 10°C, unmeasured amount of vanadium pentoxide was added and heated to 90°C for 1
hour. The solution turned dark greeny-blue as wanted, solution was decanted off the undissolved V2O5. When chilled to -10°C no precipitate formed.
When added to ethanol, no precipitate or reaction was observed.
Solution was boiled to half its volume and a large precipitate of purplish-red stuff formed (decomposed?).
Addition of ammonia resulted in a fine fluffy dark brown precipitate of ...?
When decanted and evaporated in sun, the reddish deposit was left as well.
When reddish crap was heated, evolved orangy fumes and decomposed to a bit of residue.
When reddish crap was added to water it was insoluble.
Colour of V oxides are:
VO: Grey
V2O3: Grey-black
V2O4: Blue
V2O5: Orange
NOTE: straight 70% HNO3 and 17% HNO3 (without oxalic acid) heated with V2O5 produces no reaction, 17% HNO3 solution become slightly greeny-yellow.
What part does the C2H2O4 play? any ideas on extraction?
Disturbingly, the only google reference to VO(NO3)3 is <a
href="http://www.rsc.org/CFCart/displayarticlefree.cfm?article=8-9%223%24%5C%5B.B!8'%5D%5C%5D(%3C%5C%23S5%3DX3P%40%40%3D29%23%3C%0A">here</a>
, which gives it as a yellow liquid (MP 2°C) that decomposes in water when made via N2O5. Therefore the "green-blue crystals" referenced in Fedoroff
are ???
[Edited on 18-9-2004 by Axt]
[Edited on 9-12-2005 by Axt]
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JohnWW
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I have an idea that some basic salts of V(V) - "vanadyl" - may be of [VO2]+, e.g. (VO2)2NO3. This compound should exist, but it would be
made by a different method from VO(NO3)3 if the latter (requiring an excess of HNO3 or N2O5) exists. However, almost all 15 results for a Google
search for "vanadyl nitrate" give the formula VO(NO3)3.
As for the color of V(V) oxy-compounds, the charge-transfer band giving rise to intense color should lie at a shorter wavelength than that of CrO3 and
chromates (which are yellow-orange, reflecting maximum absorbance in the blue and violet), but at a longer wavelength than that of TiO2 and titanates
(which are colorless, reflecting maximum absorbance in the near-ultra-violet; by contrast, in Mn(VII) compounds which are purple, the charge-transfer
absorption maximum is in the middle of the visible spectrum)). So V(V) compounds should be pale yellow, with maximum absorbance at the upper boundary
of the visible spectrum. In these valence states of these metals, all valence electrons are utilized, so no color can be due to transitions of
unpaired 3d electrons.
John W.
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Marvin
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Mellor seems to predate the production of solid vanadyl nitrate, but you might find this interesting.
"J.J. Berzelius (2) found that when hydrated lower oxides of vanadium, or vanadium tetraoxide were dissolved in dil. nitric acid, a blue solution
is obtained with which is not furthur oxidised even by boiling nitric acid; but when spontaniously evaporated, the solution becomes green and deposits
red crystals which still retain a little nitric acid. According to A Guyard, the tetroxide is oxidised by nitric acid to the pentoxide, and a mixture
of nitric acid and alcohol does not reduce vanadium pentoxide. He added that a solution of vanadyl nitrate can be obtained by double decomposition
between silver or barium nitrate and vanadyl chloride or sulphate repectivly. If the solution be evaporated the nitrate is decomposed with the
seperation of the pentoxide "
(2) J.J. Berzelius, Acad. Handl. Stockholm, 1, 1831; Schweigger's Journ., 62, 323, 1831; 63, 26, 1831; Pogg. Ann. 22. 1, 1831; Ann. Chim. Phys,
(1), 47, 337, 1831; Phil. Mag. (2), 10, 321 1831; (2), 11, 7, 1832; A. Guyard, Bull. Soc. Chim. (2) 25, 352, 1876.
I think this clears things up. Blue crystals didnt shout V(V) they shouted V(IV). The blue solution is vanadium(IV) and vandyl sulphate is +IV not
+V. When it evaporates it disproportionates into vandium pentoxide, which is the red solid, and leaves Vanadium(III) which is green. In the oxalic
acid description we have a vanadium pentoxide, a reducing agent, and an oxidising agent only capable of reoxidising to the +IV stage.
For me the blue crystals cannot be VO(NO3)3 anyway, but they could be VO(NO3)2, and if you were to shout out 'vanadyl nitrate' in an
assembly hall you'd get both compounds standing up and looking at eachother nervously.
The RSC link was broken when I tried it, I think this is the correct one,
http://www.rsc.org/ej/DT/1999/D9806710.PDF
Edit,
It is of course still possible that the yellow liquid in the rsc paper when frozen turns blue/green but to me this looks like information from
references for 2 different compounds being put together.
[Edited on 18-9-2004 by Marvin]
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neutrino
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Have you tried extracting the compound from the solution with any of the solvents listed in the references section
(CH<sub>2</sub>Cl<sub>2</sub>, CH<sub>3</sub>NO<sub>2</sub>, CCl<sub>4</sub>,
CFCl<sub>3</sub> and cyclohexane)?
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Axt
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<img src="http://ww1.altlist.com/~58717/pulse.altlist.com/images/vnmextract.jpg" align="right">
Yep, that description correlates exactly to the result I recieved. The "purpley-red stuff" I put into water has now completely reverted back
to orange V2O5. Also explains the "orange fumes" when heated being V2O5. So the process does seem to be one of those "If its too good
to be true, its probably not" things. Though the fact that its referenced as "needles" suggests that it can be isolated somehow, even
if only VO(NO3)2.
That wasn't the page I was trying to link to, as I was searching for "vanadium oxytrinitrate" first link on google for that term will
give the article titled "Vanadium(V) oxytrinitrate, VO(NO3)3. A powerful reagent for the nitration of aromatic compounds at room temperature
under nonacidic conditions".
Extraction with nitromethane results in a fine suspension, of what I assume to be V2O5, picture --->
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