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guy
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[*] posted on 14-3-2007 at 21:39
Pyruvic acid synthesis?


Can acetone be oxidized to pyruvic acid?

(CH3)2CO <---> CH3C(OH)CH2

The enol form can be oxidized? (as in the oxidation of acetaldehyde to glyoxal)

CH3C(OH)CH2 ---H2O---> CH3C(O)CH2OH ----> CH3C(O)CHO ---> CH3C(O)COOH
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Sauron
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[*] posted on 14-3-2007 at 22:15


Rather than hunting the wily enol, I think it would be more reasonable to prepare hydroxyacetone (probably from chloroacetone or bromoacetone, nasty) and oxidize that. That you might have a good shot at success with.
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guy
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[*] posted on 14-3-2007 at 22:22


Hmm good idea. I have cupric chloride but no lithium chloride. Can magnesium chloride be used instead since Mg2+ and Li+ are similar sizes?

edit:
In case you were wondering, those are for chlorination acetone.

[Edited on 3/14/2007 by guy]
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Sauron
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[*] posted on 14-3-2007 at 22:38


The best reagent for brominating acetone is bromine.

The best reagent for chlorinating acetone is chlorine.

Hydroxyacetone is better known as acetol and is prepare from bromoacetone by condensing it with potassium formate then treating with methanol.

Pyruvic acid is easily prepared in 50+% yield from tartaric acid (over the counter in grocery stores) and potassium bisulfate.

See Org.Syn. for details of both (online for free, www.orgsyn.org).

I believe they have a prep for bromoacetone. Use a hood, or do it outdoors, and wear a respirator and protect your eyes. Not only is Br2 nasty but bromoacetone is worse. An early tear gas.
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guy
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[*] posted on 14-3-2007 at 22:57


I thought chlorine and acetone alone yields a mixture of polychlorinated acetone. The chlorination using CuCl2 and LiCl catalyst is the most accessible and clean route for me. I probably could get some LiOCl and convert that to LiCl, but I was just wondering if MgCl2 could also do the job.

http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/h...
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Sauron
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[*] posted on 14-3-2007 at 23:01


Sorry, I don't read designer-drugs. I drew the line at Rhodium.
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guy
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[*] posted on 14-3-2007 at 23:12


Quote:
Originally posted by Sauron
Sorry, I don't read designer-drugs. I drew the line at Rhodium.


LOL, I have the official journal publication from ACS.

Anyway, so let's get past the chloroacetone. After I get chloroacetone, what do I do to convert to hydroxyacetone?
My guess is reaction with hydroxide.
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not_important
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[*] posted on 15-3-2007 at 00:12


Quote:
Originally posted by guy
Hmm good idea. I have cupric chloride but no lithium chloride. Can magnesium chloride be used instead since Mg2+ and Li+ are similar sizes?

[Edited on 3/14/2007 by guy]


Similar ionic size, and similar in some chemical properties, but aqueous MgCl2 is likely to go to a hydrated oxychloride while LiCl2 stays just that.

While you could use LiOCl to make LiCl, it might be cheap to by pottery grade Li2CO3; this may have some sodium and potassium carbonates in it but is pretty low in other metal content. Weigh some out, put it in a plastic or glass beaker/bowl with enough distilled water to dissolve the equivalent amount of LiCl. To a second beaker add enough tech hydrochloric acid to convert the carbonate to chloride. Put both beakers in a plastic container and close but don't seal - you want a pinhole leak in it. Leave it alone for a few days, the HCl will diffuse over to the LiCO3 container and react, all the iron and other crap in the tech acid stay behind in its beaker. If all the carbonate is gone, add a little more - you want a little left. Boil the LiCl solution for a little while, let cool to 30C or so, and filter it from the remaining carbonate which will retain most of the non-alkali-metals as carbonates, hydroxides, and so on.

Converting the chloroacetone to hydroxyacetone. You don't want a strong base around ketones, you'll make a bunch of gorp. However in the case of hydroyacetone, water and acid or base can lead to condensation trash, it's just not a very stable material.

As Sauron said, one route to it is via the haloacetone, reaction with alkali format or acetate, and hydrolysis of that with an alcohol. Search OrgSyn for ACETOL

An alternative route is the dehydrogenating of propylene glycol. Kind of messy and it can be frustrating getting the reaction conditions correct, but the raw material is pretty cheap.

Another route to pyruvic acid is, again as Sauron said, dehydration of tartaric acid; not very atom efficient but fairly simple. If you're not in a rush, you can take up wine making and gather potassium tartarate as a side product.
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Sauron
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[*] posted on 15-3-2007 at 00:23


@guy, hydroxyacetone = acetol, it's in Org.Syn.

Here it is as an attachment.

The pyruvic acid prep from destructive distillation of tartaric acid is easy. 600 g freshly fused KHSO4 and 400 g tartaric acid are ground together in a mortar to make an intimite mixture. Place in a 3L RB flask fitted with a condenser for downward distillatioin, which is filled with water but the water is not circulated or flowing. Heat with an oil bath regulated to 210-220 C. Collect till no more liquid comes over. Fractionate product under vacuum, the pyruvic acid comes over at 75-80 C / 25mm. Yld 117-128 g.

Given the cheapness and availability of the reagents this is really rather hard to beat. Dry distilling tartaric acid alone also works but with lower yield, you might consider that if you can't conveniently fuse the potassium bisulfate. The KHSO4 was chosen from a variety of dehydrating agents tried, and the above conditions were optimized.

So unless you want to break "new" ground, I'd drop the acetol route (even though I suggested it). but I put those quote marks there because you'd better see ref. 5 in that Org.Syn. piece.

Pastureau, Bull.Soc.Chim. 4, 5, 227 (1909)

Direct oxidation of acetone with Baeyer-Villager acetone-peroxide reagent gives acetol and pyruvic acid.

In other words 98 years too late.

[Edited on 15-3-2007 by Sauron]

Attachment: CV2P0005.pdf (116kB)
This file has been downloaded 722 times

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[*] posted on 15-3-2007 at 02:25


Mono-chloroacetone can be had by adding acid (the halogenation of acetone is acid and base catalyzed since it's the enolate that reacts, however if a base is used then polyhalogenation will undoubtly occur), cooling to sub-zero temperature and then adding 1 mol eqvivalent of liquid chlorine produced by condensing Cl2 (g) by means of dry ice in acetone. The addition is done with a Pasteur pipette and intense stirring.



\"Those who say do not know, those who know do not say.\" -Lao Tzu
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[*] posted on 15-3-2007 at 10:51


With all the posts on acetone chlorination with TCCA on this forum, you just have to bring out chlorine, even liquid chlorine!
Guy, is your intention to prepare pyruvic acid? If so then stick to the original preparation from tartaric acid. There is nothing simpler than this.
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[*] posted on 15-3-2007 at 18:21


I have a question about the fused NaHSO4. Fused means melted, correct? I'm afraid my glassware will crack when the solid cools.
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[*] posted on 15-3-2007 at 19:18


Quote:
Originally posted by guy
I have a question about the fused NaHSO4. Fused means melted, correct? I'm afraid my glassware will crack when the solid cools.


Melt the KHSO4, then pour it onto a thick metal plate or stone slab where the melt will quickly cool. Knock it loose, break it up a bit and bottle, or grind it to poder and use right away.
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[*] posted on 15-3-2007 at 19:55


Quote:
Originally posted by not_important
Quote:
Originally posted by guy
I have a question about the fused NaHSO4. Fused means melted, correct? I'm afraid my glassware will crack when the solid cools.


Melt the KHSO4, then pour it onto a thick metal plate or stone slab where the melt will quickly cool. Knock it loose, break it up a bit and bottle, or grind it to poder and use right away.


OK, can I ask though why does it need to be fused?
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Sauron
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[*] posted on 15-3-2007 at 20:45


To thoroughly dessicate it before it is mixed with the tartaric acid.

Fusing drives off water of crustallization. You fuse it then break up the melt and powder it then grind it with the acid. No lumps!
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