ParadoxChem126
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Sodium Dichromate Substitute?
Does anyone know of an oxidizing agent with a similar strength to acidified sodium dichromate, but less toxic and not carcinogenic? Also, it would be
nice if it was not really expensive. I would like to make ethanal through the oxidation of ethanol, but I really don't want to have to deal with the
acidified sodium dichromate.
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Pyro
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http://en.wikipedia.org/wiki/Sodium_dichromate
it's not so bad. and I believe it is only carcinogenic by inhalation, not by ingestion or skin contact.
potassium dichromate is cheaper.
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ParadoxChem126
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Still, I don't have a fume hood and I really don't want to risk getting cancer.
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Pyro
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just wear a dust mask, it's not that mobile. anyway, the risks from one time exposure are reasonably small.
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DraconicAcid
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It's not the strength of the oxidizing agent that's important for most organic oxidations, but the kinetics. Atmospheric oxygen is more than strong
enough to oxidize ethanol to ethanal (and to acetic acid, and to carbon dioxide). Platinum wire will catalyze the oxidation of methanol to
formaldehyde at 40-60 oC (this is given as a demo in Chemical Curiosities), and I seem to recall reading that copper will catalyze the oxidation of
ethanol to ethanal under the right conditions (I'll try to find a reference later).
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Hexavalent
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I have used potassium dichromate many times before without the use of a fume hood. If anything, because it is suspected to be carcinogenic by
inhalation, and a hood can disperse fine powders, using one increases the risk!
Just wear a dust mask, try to buy fairly coarse crystals and use a spoon to transfer the material, as opposed to pouring out of the bottle. I always
like to wipe down the bench with a bisulfite solution when I'm done, just to clean up any remaining traces.
Do not fear chemicals: respect them, and use them carefully.
[NB - if you want to isolate the acetaldehyde, you'll need to be very careful as it easily oxidizes into acetic/ethanoic acid - you'll almost
certainly need to distill it out of the reaction flask as soon as it is formed.
[Edited on 10-4-2013 by Hexavalent]
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Adas
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Quote: Originally posted by DraconicAcid  | | It's not the strength of the oxidizing agent that's important for most organic oxidations, but the kinetics. Atmospheric oxygen is more than strong
enough to oxidize ethanol to ethanal (and to acetic acid, and to carbon dioxide). Platinum wire will catalyze the oxidation of methanol to
formaldehyde at 40-60 oC (this is given as a demo in Chemical Curiosities), and I seem to recall reading that copper will catalyze the oxidation of
ethanol to ethanal under the right conditions (I'll try to find a reference later). |
Copper can catalyze it at higher temperatures. You can find a lot of videos about it. Copper is also capable of dehydrogenating ethanol under anoxic
conditions and higher temps.
Rest In Pieces!
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