guy
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iron/glycerol compound
Fe2O3, NaOH, and glycerol were added into a crucible and heated in an open flame. The mixture started to boil with lots of smoke evolving. Then
water was added to the mixture was cooled down and filtered. What wa left was a clear(as in no particles) dark, red-brown solution. This compound is
stable even when highly diluted (giving a golden-brown solution).
Other notes: I tried just Fe2O3/glycerol and it didn't work.
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I just found out that glycerol decomposes to the toxic Acrolein. I accidently breathed some of the smoke, will I die?
[Edited on 8/11/2006 by guy]
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not_important
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Not from a trace : http://www.atsdr.cdc.gov/tfacts124.html
as for the less pressing issue of the complex, you may be getting some air oxidation of the glycerol with the base there.
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Nicodem
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The conditions were extreme enough and oxygen was present so to allow traces of sodium ferrate (IV) or (VI) to have formed (Na2FeO3 and Na4FeO5). I
don't know what's the color of ferrate salts, but I could guess they are red. However I would have imagined the ferrates are strong enough oxidants to
oxidize glycerol. Perhaps glycerol actually did get oxidized to some acids which on turn dissolved some Fe2O3 forming a red solution.
Anyway, your experiment does not demonstrate the formation of a complex.
PS: You are more likely to get cancer from acrolein in fried potatoes in your favorite fast food by chronic exposure than a one time acute exposure in
such an experiment. Anyway, acrolein has a sharp odor to warn you about its presence.
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guy
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| Quote: | Originally posted by Nicodem
Anyway, your experiment does not demonstrate the formation of a complex.
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So do you think it is regular Fe3+? Adding NaOH to it causes NO precipitate. Ferrate(VI) ions will decompose rapidily if not in high pH.
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not_important
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guy, check these
http://www.freepatentsonline.com/7034172.html
http://www.deas.harvard.edu/environmental-chemistry/publicat...
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chemoleo
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No way it's going to be ferrate. Read the thread on it. It's violet, highly unstable, and would undoubtedly oxidise any of the glycerol. Even BaFeO4,
which is insoluble, isn't exactly stable.
| Quote: | | So do you think it is regular Fe3+? Adding NaOH to it causes NO precipitate. Ferrate(VI) ions will decompose rapidily if not in high pH.
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Guy, this means nothing, as your solution is already highly basic anyway. Check the pH first, then neutralise.
Did you weigh things? Or just chuck it together randomly?
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Nicodem
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Yes, I stand corrected. Indeed, there is no way any ferrate could form in such a reductive ambient when the oxidative potential of ferrates is
considered.
Guy, try the same thing with NaOH/glycerol only. I bet the solution will become brown-red.
Solutions of NaOH in EtOH become red if left standing exposed to air in a couple of days at room temperature (the color indeed reminds of some Fe(III)
salts or oxide). I always thought it was because the ethoxide ions would be easily oxidized by oxygen forming compounds that would self condense in
basic conditions to some brown-red, indefinable crap. Some brown tar actually begins to precipitate if left standing several days. I would assume
something similar would happen to glycerol as well, especially if the oxidation is catalyzed by the presence of Fe(III) and speeded by heat.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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not_important
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Guy's results may be related to the Guerbert reaction, part of a set of reactions taking place at elevated temperatures in the prescence of strong
base. These give branched alcohols built up from simplier alcohols, and carboxylic acids from those alcohols
http://www.zenitech.com/documents/guerbet_chemistry.pdf
Coming into play with compounds that can give unstatured carboxylic acids, although generally at a bit higher temperature, is the Varrentrapp and
related reactions, which sometimes affect saturated acids as well.
Nicodem's example may be related to the oxidation shown in the Guerbet PGF, oxidation of alcohols in the presence of strong base shows up in other
cases.
edit - use the correct names of people, duh.
[Edited on 12-8-2006 by not_important]
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guy
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| Quote: | Originally posted by Nicodem
Yes, I stand corrected. Indeed, there is no way any ferrate could form in such a reductive ambient when the oxidative potential of ferrates is
considered.
Guy, try the same thing with NaOH/glycerol only. I bet the solution will become brown-red.
Solutions of NaOH in EtOH become red if left standing exposed to air in a couple of days at room temperature (the color indeed reminds of some Fe(III)
salts or oxide). I always thought it was because the ethoxide ions would be easily oxidized by oxygen forming compounds that would self condense in
basic conditions to some brown-red, indefinable crap. Some brown tar actually begins to precipitate if left standing several days. I would assume
something similar would happen to glycerol as well, especially if the oxidation is catalyzed by the presence of Fe(III) and speeded by heat.
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I tried NaOH and glycerol only and nothing happened. Was your color very dark?
And how can ethanol and NaOH becomoe colored? Was your's pure ethanol?
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not_important
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Alcohols can be oxidised, even by air, when hydroxide is present, aldehydes or ketones and acids can be formed. Aldehydes and base go to condensation
products, get enough carbonyls and double bonds and you have colour.
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guy
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| Quote: | Originally posted by not_important
Alcohols can be oxidised, even by air, when hydroxide is present, aldehydes or ketones and acids can be formed. Aldehydes and base go to condensation
products, get enough carbonyls and double bonds and you have colour. |
Oh that's interesting. What would the mechanism be? The formation of an alkoxide, then oxidation of the alkoxide by oxygen? 2RCH2O- + O2 --->
2RCHO + 2OH-
And if you happen to have any sources on that it would be cool.
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JohnWW
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Ferrate (VI) can be made by oxidation of alkaline Na or K ferrite (III) by Cl2 gas, hypochlorite, or reagents like plumbate or bismuthate, or
electrolytically. The color of ferrate (VI) salts is magenta; resembling permanganate, but somewhat more reddish, due to the intense charge-transfer
absorption band in the visible part of the spectrum.
If perferrate (VII) could be made (and it probably could be, by electrolysis of cold alkaline ferrate solution at sufficiently high voltage), the
charge-transfer band would be shifted to a still longer wavelength and be even more intense, and it would probably be an intense bluish-purple color
(bluer than permanganate).
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not_important
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Sorry, guy, no good references. Almost everything that gives any detail relates to fusion or at least elevated temperatures with strong aqueous
solutions; the more room temperature ones have all been of the "this reaction happens" mention. I suspect that it is slow enough and leads to such a
mess of products that it's attracted little attention, showing up only in such publications as the Wallachian Journal of Natural Philosophy or Annals
of the Technical Arts in Ragusa.
The Guerbert pdf has a reference or two for caustic fusion oxidations.
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