careysub
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Substituting POBr3 fro POCl3
Would one reasonably expect that POBr3 could be substituted for POCl3 in most syntheses?
This question occurs to me since Elemental Scientific currently has PBr3 as a special order chemical, from which POBr3 can be made through various
oxidation processes, but they do not have PCl3 or PCl5 (or POCl3 itself).
Phophoryl chloride is a versatile reagent but seems hard to get these post-9/11 days, what with being an important G-agent nerve gas precursor and
all.
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gdflp
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Just an idea, but you could ask tomholm if he could add it to his special order list. POCl3 seems to be much cheaper than PBr3.
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careysub
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Quote: Originally posted by gdflp  | | Just an idea, but you could ask tomholm if he could add it to his special order list. POCl3 seems to be much cheaper than PBr3.
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Well, he can't ship PCl3, so I assumed this would apply to POCl3 as well.
If POBr3 is not a reasonable substitute then the Tarbutton synthesis from NaCl and P4O10 (>250 C) looks promising. I see discussion of it, but has
anyone on this forum ever actually done it?
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JAVA
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What is the Tarbutton synthesis ?
It's easy to convert organic acids into acyl bromides with PBr3, I don't should know how to prepare POBr3 from PBr3
or POCl3.
Red phosphorus in DCM and slowly add waterfree bromine into the mixture, it's straightforward and cheap.
[Edited on 30-9-2014 by JAVA]
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Metacelsus
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. . . if you can easily get red phosphorous.
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Chemosynthesis
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Carey, I believe the answer is yes, though yields may be reduced depending on what you are doing. Other than just generalizing on the
interchangeability of halogens in reactions, the basis for my answer comes from schemes 1 and 2 of PMCID: PMC2613833 and/or pages 28-30 of The
Chemistry of Heterocyclic Compounds, The Naphthyridines By Desmond J. Brown, Jonathan A. Ellman and Edward C. Taylor.
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careysub
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| Quote: Originally posted by JAVA | What is the Tarbutton synthesis ?
It's easy to convert organic acids into acyl bromides with PBr3, I don't should know how to prepare POBr3 from PBr3
or POCl3.
Red phosphorus in DCM and slowly add waterfree bromine into the mixture, it's straightforward and cheap.
[Edited on 30-9-2014 by JAVA] |
Tarbutton synthesis, well I described it in the sentence where I used the name, but here is a thread that also contains the original 1940 article
attached:
http://www.sciencemadness.org/whisper/viewthread.php?tid=9&a...
Phosphorus is unavailable for all practical purposes in the US, so it does not matter how straightforward it is. "Cheap" it ain't if you can't buy the
reagent.
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Nicodem
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Thread Moved
1-10-2014 at 22:26 |
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