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Author: Subject: Glyoxylic Acid Synthesis
Chainhit222
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shocked.gif posted on 11-8-2010 at 20:23
Glyoxylic Acid Synthesis


So, I attempted to create glyoxylic acid via this route taken from a patent:
( http://www.patentstorm.us/patents/4698441/fulltext.html )
EXAMPLE 2

154 g of 45% nitric acid was added dropwise to 435 g of an aqueous solution containing 19.96% of glyoxal, 0.49% of glyoxylic acid and 10.02% of hydrochloric acid, at a temperature of 40° C., over four hours, whereby glyoxal was oxidized at 40° C. with an oxidizing agent composition formed in situ. After one hour, at the same temperature, from the completion of the addition of nitric acid, a reaction solution containing 16.58% of glyoxylic acid and 0.007% of nitric acid was obtained. This reaction solution also contained 0.84% of glyoxal, 7.34% of hydrochloric acid and 3.31% of oxalic acid. The conversion of glyoxal was 94.7%, the selectivity for glyoxylic acid was 84.7% and the yield was 82.1%.

http://img130.imageshack.us/img130/8813/gly1q.jpg
(the setup)

I scaled down the synthesis by 50% and ran the reaction (addition took 1.5 hours and it was left to run by itself for 1.5 hour, not optimal conditions but I think is close enough). The reagents were ultrapure JT baker nitric acid, muratic hardware store hcl, and glyoxal from a photography place. The patent mentioned that the glyoxal need not be pure.

After the reaction finished, I vacuum distilled it under heavy magnetic stirring at about 100mmhg. The first fraction came over at a low temperature, It was probably a mixture of residual glyoxal and water, so it was discarded. The mixture then started coming over at around 51-53c (I am using a alcohol thermometer). I got like 90 ml of distilate on this fraction, I stopped the distillation when the temp started rising to 60c or so. I assume the stuff in this fraction is a mixture of water and glyoxylic acid? Shows up as a low ph acid on ph paper.

The distilling flask residue is a thick viscous liquid, somewhat similar to honey in consistency. I am not sure what this is. Could this perhaps be the glyoxylic acid?

I put the thick liquid from the distilling flask into the freezer for 15 min, and it is now a extremely thick gel. I poked it with a knife and gave it the knife a lick (does not really stick to the knife, its too viscous when cold), but the knife tasted pretty sour.

Has anyone delt with this stuff before? Which fraction do you think is the glyoxylic acid?


p.s. please dont post alternative synthesis routes in this thread, start your own thread if you want to discuss other methods of producing it. This thread is about making glyoxylic acid from glyoxal and hno3.


Glyoxal bp = 50c
glyoxylic acid bp = 111c (depends where you look though)

using sigma's nomograph and my vacuum pressure I got 48c, but I'm guessing it was coming over with water. I will distill that 90ml fraction with a vigruex column next, in order to reach higher purity.

[Edited on 12-8-2010 by Chainhit222]




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bbartlog
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[*] posted on 12-8-2010 at 07:07


Quote:
I assume the stuff in this fraction is a mixture of water and glyoxylic acid?


Does not sound like a good assumption based on the bp you observed. The obvious conclusion would be that this is unreacted glyoxal, possibly with some other stuff.

If your product is bp 111C and you stop distillation at 60C, then it isn't clear why you would expect to find it anywhere other than in the residue. I don't know that further distillation will be useful, however, since HCl has an azeotrope with water right near the bp of your product (107C IIRC). Maybe add just enough NaOH to turn the HCl to NaCl and then distill? This would also have the advantage that you aren't leaving a bunch of HCl in solution to possibly promote acid condensation reactions.

One other thing, I notice that in the patent they start with 0.49% glyoxylic acid as one of the reagents. Did you? It would be unusual to mention it if it didn't play some role.
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Chainhit222
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thumbup.gif posted on 12-8-2010 at 11:51


Quote: Originally posted by bbartlog  
Quote:
I assume the stuff in this fraction is a mixture of water and glyoxylic acid?


Does not sound like a good assumption based on the bp you observed. The obvious conclusion would be that this is unreacted glyoxal, possibly with some other stuff.

If your product is bp 111C and you stop distillation at 60C, then it isn't clear why you would expect to find it anywhere other than in the residue. I don't know that further distillation will be useful, however, since HCl has an azeotrope with water right near the bp of your product (107C IIRC). Maybe add just enough NaOH to turn the HCl to NaCl and then distill? This would also have the advantage that you aren't leaving a bunch of HCl in solution to possibly promote acid condensation reactions.

One other thing, I notice that in the patent they start with 0.49% glyoxylic acid as one of the reagents. Did you? It would be unusual to mention it if it didn't play some role.


It was a vacuum distillation... I mentioned 100mmhg and nomographs. I think they are just using crude glyoxal that has residual glyoxylic acid because it was probably over oxidized by nitric acid during production from oxalic acid, and not economical for the manufacture to distill out 1% impurity.

[Edited on 12-8-2010 by Chainhit222]




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Chainhit222
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cool.gif posted on 12-8-2010 at 18:59


http://pubs.acs.org/doi/abs/10.1021/i360020a012

"the product when cooled to room temperature is a colorless, very viscous liquid"

It looks like thats my glyoxylic acid. Color must be from residual HCl (in the journal its prepared from ozone)

http://img180.imageshack.us/img180/7882/viscousliquid.jpg



[Edited on 13-8-2010 by Chainhit222]




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[*] posted on 13-8-2010 at 16:49


I am very interested in glyoxylic acid for synthesizing vanillin.

You could make the glyoxal from TCCA and ethylene glycol. The BP is 51 degrees while the over and under oxidized variations are much higher This makes it easy to remove from the reaction as its formed.




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Chainhit222
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[*] posted on 13-8-2010 at 22:42


Quote: Originally posted by mr.crow  
I am very interested in glyoxylic acid for synthesizing vanillin.

You could make the glyoxal from TCCA and ethylene glycol. The BP is 51 degrees while the over and under oxidized variations are much higher This makes it easy to remove from the reaction as its formed.


That is a nice OTC method, but you can buy it for 20$ a pint from photography places.

[Edited on 14-8-2010 by Chainhit222]




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[*] posted on 28-7-2014 at 04:39


you could also examine the attached article procedure, which describes the use of Mg powder to reduce Oxalic acid... Certainly the most practicable route I can imagine or even dream of:D

Attachment: Benedict.A.Note.on.Preparation.of.Glyoxylic.Acid.pdf (529kB)
This file has been downloaded 1304 times





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[*] posted on 30-7-2014 at 18:50


That's amazing, just react it with magnesium. Are there any other references? This one is over 100 years old.



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[*] posted on 7-10-2014 at 18:53


Well since the thread has been recently revived...

Chainhit...Were you ever able to isolate glyoxylic acid by this method?
If so, in what yield? Was it confirmed by TLC, bp, or mp of the salt?

Also, aliced...have you performed the reaction with magnesium metal? Unable to find any other mention of magnesium used this way in the literature.

Very interested in the preparation of this compound..expect a full write up in the near future if an effective method is decided upon.
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