Polverone
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oddball methods for pyruvic acid
This doesn't really belong in the dry distillation thread, but I thought it interesting enough to post.
Probably not more practical than methods already under consideration, but somewhat interesting due to lack of acids:
| Quote: | Decomposition of Tartaric Acid in the Presence of
Glycerol at a High Temperature. M. K. JOWANOWITSCH.
Eight parts of tartaric acid and ten parts of glycerine yield on distillation at 180o a small quantity of acrolein ; at 200o an oily liquid yielding
crystals arid at 260o products, with very penetrating odor. During the whole operation CO2 is given off. The crystals on purification are found to be
pyruvic glyceride, cannot be distilled without decomposition, are easily soluble and yield, on boiling with water and CaCO3, glycerol and calcium
pyruvate.
The mother liquor of the crystals is a mixture of water, glycerol, acrolein and pyruvic acid. (Monatshefte fur Chemie, 6,467.)
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Of course there are many older references that speak of distilling tartaric acid by itself and fractionating the obtained acids to obtain pyruvic acid
in pure form. But that sounds like too much work and waste, even if foaming isn't so bad.
If you have easy access to lactic acid or its salts -- much cheaper than pyruvic acid -- it might be worthwhile attempting its oxidation to pyruvic
acid. According to "The Chemical Synthesis of Vital Products and the Interrelations Between Organic Compounds," available on Google Books, "lactic
acid gives pyroracemic (pyruvic) acid on oxidizing the calcium salt with potassium permanganate (Beilstein and Wiegand, Ber. 17, 840)." Other sources
indicate an excess of lactate must be used, because permanganate oxidizes pyruvate.
A tantalizing snippet from Rodd's Chemistry of Carbon Compounds says "Careful oxidation with permanganate, or palladium dehydrogenation in the
presence of a hydrogen acceptor such as quinone, yields pyruvic acid." I'd have to go into the library to recover more than that one line from Google
Books.
If dealing with ester intermediates is an acceptable complication, Organic Syntheses has a prep of ethyl pyruvate from ethyl lactate with KMnO4 in 50%
yield, Coll. Vol. 4, p.467 (1963); Vol. 31, p.59 (1951).
Activated MnO2 with lactic acid, perhaps? That would be a real research project and not just tuning a known method, though.
If you obtain calcium pyruvate, either commercially or by your own hand, I think it can be usefully converted to the free acid with oxalic acid. I
have prepared (for example) pure tartaric acid by grinding an oxalic acid solution with a slight excess of calcium tartrate in hot water. The
solubility of the source calcium salt is low, but calcium oxalate is much less soluble still, and the mixture did not become a horrible mush as more
concentrated calcium solutions may do when precipitated.
PGP Key and corresponding e-mail address
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not_important
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Dealing with an ester might be the best route, as the free acid is supposed to be difficult to keep around for extended periods.
If you have access to ether, treating a slight excess of calcium pyruvate with concentrated hydrochloric acid, and then adding the reaction mix to
ether should work, leaving a ppt of the calcium salts and an ether solution of the free acid.
200 C isn't too bad, and there appears to be a wide temperature range that is acceptable before other reactions hurt the yield. The mother liquor
might be reusable, with some dehydration by distilling out water first, which could raise the overall yields.
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Sauron
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But there's the indescribable joy of working with byproduct acrolein, which is one of the tiny number of proven human carcinogens. (as opposed to
animal carcinogens or other classes of cancer suspect agents.)
Glycerin here is just being used as a heating medium, I'd look for some other high boiler that will be even more inert so that you get no acrolein and
no pyruvic ester, just pyruvic acid.
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Organikum
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Wasn´t that glycolic acid from the patent I posted? I mean not only heating medium but also dehydrating?
Isn´t it a mild dehydrating agent whats needed, mild and stable up to 180°C?
Also the reference in the Ullmann spoke of glycolic acid, isnt it possible that it was NO typo that they wrote ethylene glycol?
I think I might give this a try. The glycol.
PS: A quick look into the Merck makes me think that IF AT ALL then diethylene glycol might be the better choice.
[Edited on 28-5-2007 by Organikum]
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S.C. Wack
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Quote: Originally posted by Polverone  |
A tantalizing snippet from Rodd's Chemistry of Carbon Compounds says "Careful oxidation with permanganate, or palladium dehydrogenation in the
presence of a hydrogen acceptor such as quinone, yields pyruvic acid." |
The KMnO4 part, here: http://books.google.com/books?id=NUXOAAAAMAAJ&pg=PA259
Bull. Soc. 259, (1908)
The yields suck, and it calls for phenylhydrazine for isolation.
A un mélange refroidi vers —2° de 10 gr. d'acétone et de 36 gr. de permanganate de potassium dissous dans 1800 gr. d'eau, on ajoute en une fois
une solution de 5 gr. de soude dans 50 gr. d'eau également à — 2°. Pendant une 1/2 heure environ on maintient cette température, puis on la
laisse remonter à 3° ou 4°. 1 h. 1/4 après le début de l'expérience, la teinte rouge du permanganate a disparu. Le liquide est rapidement
essoré, acidulé par HCl et additionné d'une solution de chlorhydrate de phénylhydrazine. La phénylhydrazone pyruvique se précipite; on l'essore
et on la fait cristalliser dans l'alcool bouillant. On en obtient 2.3 g.
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unome
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Maybe grab some Dalopon (sodium 2,2-dichloropropionate) and perform the hydrolysis thereon?
Hydrolysis of aqueous solutions of sodium 2,2-dichloropropionate under self-induced alkaline conditions
Fred S. Tanaka, Ronald G. Wien]/i]
J. Agric. Food Chem., 1973, 21 (2), pp 285–288
DOI: 10.1021/jf60186a007
| Quote: | Abstract
Aqueous solutions of sodium 2,2-dichloropropionate were previously reported as having an approximate pH of 5 to 6. The data obtained in this study
shows that freshly prepared solutions of greater than about 0.9m concentration exhibit a basic pH. Upon standing however, these salt solutions become
acidic due to the hydrolysis of the 2,2-dichloropropionate to yield pyruvate and hydrochloric acid. The approximate pH of the sodium
2,2-dichloropropionate solutions is estimated at different concentrations, and the rates of pH change due to hydrolysis are reported for dilute,
intermediate and high concentrations of material under mildly alkaline conditions. |
BTW If anyone can get that into ref's I'd appreciate a copy of the article by PM
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UnintentionalChaos
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Just a thought I'd like to interject on the subject-
Given the success of the nitric acid oxidation of 1,3-propanediol to malonic acid (a fairly sensitive substrate) and given the ready availability of
lactic acid, is it possible that pyruvic acid could be prepared in an analagous manner?
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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