DFliyerz
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Distillation Over Metal Dust
A very old (and still fairly useful) method of deoxygenating hydrocarbons is distilling the material with zinc dust, such as in the deoxygenation of
phenol to benzene. I am wondering, is zinc the only metal that this process can be performed with? Could copper, nickel, etc. be used instead, or just
zinc? Would aluminum explode?
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unionised
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Part of the answer may be that zinc was readily obtained as "dust".
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blogfast25
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Granulometry should only affect kinetics, not actual reductive capacity.
I think Mg powder might work very well here. Perhaps Al shavings or turnings too.
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unionised
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You seem to have missed the point.
Powdered gadolinium probably works too, but you couldn't get it from the smelting works in 1900.
It might be interesting to try it with pyrophoric iron.
Also, three's kinetics and kinetics.
it's plausible that the rapid reaction with the dust happens quicker than, for example, some rearrangement but that if you have to work slowly because
the metal is in big lumps, the rearrangement is quicker so you would get a different product.
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DFliyerz
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I don't know why it took me so long to realize (even though I have cooled molten zinc in water), but zinc doesn't react with water. Therefore I could
probably precipitate a decently fine powder of it by dissolving impure zinc in HCl and displacing it with aluminum metal. I'll be sure to try it when
I get home today, and report on my results.
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byko3y
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https://en.wikipedia.org/wiki/Rieke_metals
Also, as you may know, zinc is the only metal capable of reducing ketones directly to hydrocarbons in Clemmensen reduction. However, mechanism of the
reaction is complicated and for complex compounds can give unexpected product (double bound reduction, cleavage, etc.).
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UC235
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Zinc is fairly unique in that it is easy to powder finely without significant oxide formation. Supposedly, it is very brittle above about 210C, but
below its melting point at 420C, and beating/pounding it crushes it into dust.
The easiest way to get this temperature range is probably to melt it, cool, and start crushing as soon as it's solid.
Zinc does react with water, though it may not be apparent from quenching the metal in large chunks. The finer the material, the more rapid it's
oxidation, such that attempting to displace it from liquid would probably produce a mess containing significant hydroxide content..
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subsecret
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Distillation from magnesium turnings is a good way to dry some solvents that react with alkali metals.
Fear is what you get when caution wasn't enough.
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Oscilllator
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Quote: Originally posted by UC235  | | Zinc is fairly unique in that it is easy to powder finely without significant oxide formation. Supposedly, it is very brittle above about 210C, but
below its melting point at 420C, and beating/pounding it crushes it into dust. |
That's very interesting. I have noticed when melting down Aluminium chunks that the aluminium also becomes extremely weak and crumbly a little below
its melting point, so perhaps that same method could also be used for Aluminium.
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