TheChemiKid
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Pinacol Synthesis Variations
I am interested in attempting the synthesis of Pinacol from Acetone.
It entails using Magnesium and Mercuric Chloride, then water to react with Acetone to form Pinacol. I was wondering if anything could replace the
Mercuric Chloride, such as Gallium?
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Dr.Bob
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Try searching google for "catalyst pinacol acetone", I found lots of catalysts:
http://www.chemtube3d.com/RAD-pinacolcoupling.html
http://www.organic-chemistry.org/namedreactions/pinacol-coup...
http://www.arkat-usa.org/get-file/42209/
http://chem.ccnu.edu.cn/klpcb/www/wuanxin/UpLoad/20079101882...
http://books.google.com/books?id=NYYMD-KYZb4C&pg=PA284&a...
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TheChemiKid
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Thank you so much!
I would presume the Magnesium would need the surface cleaned for this reaction. Would Iodine work for that?
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Dr.Bob
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Depends on the conditions used. I prefer to just grind up the Mg fillings in a mortar and pestle just before use, and then maybe even wash them with
ether once. If they are freshly ground up some, they often work well. Just don't try to grind them in a blender, that can lead to bad fires.
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TheChemiKid
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Thanks for that.
I have one more question. In the chemtube procedure, it specifies to use benzene. I have very limited amounts of benzene, so I was wondering whether
toluene or xylene could be used in its place.
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Electra
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Never done this particular reaction myself but in my research into Vanadium I remember frequently running into it being used as a Pinacol coupling
catalyst in the VCl3 form.
http://www.ncbi.nlm.nih.gov/pubmed/16209617
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Dr.Bob
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Quote: Originally posted by TheChemiKid  | | In the chemtube procedure, it specifies to use benzene. I have very limited amounts of benzene, so I was wondering whether toluene or xylene could be
used in its place. |
I almost any reaction, toluene or xylene can be used as the solvent, as long as they are non-reactive (which they should be in an aldol reaction), and
the BP will change, so the temperature of reflux will go up, which may speed up the reaction. There are some few cases where they cannot be
interchanged, but in most cases that works fine.
I rarely use benzene now, the only case I found where it was absolutely necessary was in purifying a compound by chromatography, where the Rf
difference between two aromatic compounds was much larger in benzene than in toluene, likely due to benzene's symmetry making it slightly less polar
than toluene, which has a larger dielectric constant. Toluene also forms different azeotropes than benzene, but that can often be dealt with proper
selection of solvents.
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TheChemiKid
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Thank you, when I have tried this reaction, I will post a detailed writeup, though it may also be put in prepublication. If so, I will post a link.
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