DDTea
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Reduction of Phosphate Esters
My Organic Chemistry professor told an interesting story during class the other day. I don't remember what his point was, but in it he mentioned
how he was once given the task of reducing a phosphate triester to a trialkyl phosphate using Zinc dust:
O=PR3 --(Zn)--> PR3
The story goes that he was having no luck, but it was a proven procedure from 1887. So finally he asks his instructor what he's doing wrong...
The instructor looks at his equipment and reagents, then dumps the Zinc powder on the floor and shuffles all over it. "Sweep it up and try
again," he says. The reaction worked beautifully with the addition of the "catalytic crud," as he called it.
In 1887, they did not have pure reagents--it was mostly stuff they'd made themselves. So whatever was on the floor helped my professor's
zinc powder out 
But that aside, this is a very interesting reaction. Trialkyl Phosphates are fairly unreactive in the ways I'd like ;-), boring, and
aren't so hard to get [although they are possible carcinogens]:
Ag3PO4 + RI --> R3PO4 + AgI
But conversion to a Phosphite gives a direct precursor to toxic organophosphates. From there, an Alkyl Halide could be reacted with it to form a
Phosphoryl bond, according to the Arbusov Reaction.
So of course I want to know the details of how his Zinc reduction worked, but I dared not ask. When he drew the structure "O=PR3" on the
board, I assume the R's weren't meant to represent Phosphorus-Carbon bonds, but P-O-C bonds.
After class, I promptly went to the chemistry library to find whatever information I could on this reaction, but could find nothing...
So, what do you all think? Any ideas on how to approach this?
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
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The_Davster
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Well, I do not know much about the chemistry here, but couldent you email your professor from a fake hotmail one to ask? It would work well if you
have a large lecture class, but not as well as a small one where the proff attempts to get to know everyones names.
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DDTea
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Unfortunately, it is just that kind of small class--the special organic chem class for chemistry majors, so of course our professor wants to know us.
That's not so bad, only we are on odd terms which I don't feel like getting into I might just ask though.
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
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DDTea
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I asked my teacher after class today to clarify the reaction he mentioned earlier. He says it only works with phosphine oxides, not
phosphoric acid esters. Phosphine Oxides are compounds where carbon chains are bonded directly to the central Phosphorus atom.
Therefore, this reaction can't be used in the way I imagined earlier. Oh well.
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Madandcrazy
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Maybe interested to this topic,
some phosphine chemicals are liquids and can be use for any
syntheses, subtitutions or recations to convert water.
examples:
dichlorophenylphosphine
dichlorodiphenylphospine oxide
hexamethyltriaminophosphine
[Edited on 3-5-2006 by Madandcrazy]
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