morsagh
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Glyoxylic acid by magnesium reduction
There´s very nice video by chemplayer (hi if you read this)
https://www.youtube.com/watch?v=kwsZlH2l_oQ
Does anybody knows how effective is this reduction? Couldn´t be magnesium oxalate filtred off and than extracted pure glyoxylic acid in water
solution by adding phosphoric acid and filtring off insoluble magnesium phosphate?
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careysub
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Seems like it is making the magnesium salt of glyoxylic acid?
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Waffles SS
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I tried this method several times and each time i got unchanged oxalic acid
reference of that video:
https://www.sciencemadness.org/whisper/viewthread.php?tid=14...
Oxidation of Glyoxal is best method for synthesis of glyoxylic acid
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morsagh
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Anybody who has tried and get some product?
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unionised
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The bubbles of hydrogen are a give away here. What is reduced by the magnesium is water.
There may be some small yield of other products but it doesn't seem worthwhile.
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Waffles SS
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I attached all possible way for synthesis of glyoxylic acid.
Attachment: glyoxylic acid.pdf (1.7MB)
This file has been downloaded 1455 times
One of interesting way that i tried is Decomposition of N-Chloro- Glycine in Alkaline Medium.(reaction of Glycine with sodium hypochlorote and Sodium
hydroxide)
I was unsuccessful in scaling up of this method
| Quote: |
Decomposition of N-Chloro-a-amino Acids in Alkaline Medium
X. L. Armesto, M. Canle, M. Losada and J. A. Santaballa"
Universidad de la Coruiia, Facultad de Ciencias, Departamento de Quimica Fundamental e Industrial,
A Zapateira, sin 15071 La Coruiia, Spain
J. CHEM. SOC. PERKIN TRANS. 2 1993 page 181
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[Edited on 12-6-2016 by Waffles SS]
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morsagh
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In the paper about Mg reduction was written they were trying this for Adamkiewicz reaction of tryptophan and glyoxylic acid and they were succesful,
how were you testing your solutions after reduction?
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Waffles SS
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I did Brady's test
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morsagh
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If i´ll have time tomorow in lab i´ll try this. Maybe try exact titration. Is iodine reduced by oxalic acid? If no then i´ll try to do iodometry.
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chemplayer...
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Hi back. The reaction definitely generates 'something' aldehyde-like because the reaction mixture ends up with a strong aldehyde (like acetaldehyde
but slightly different, smoother and less sharp) aroma.
But as others have commented, most of the hydrogen is just given off as gas rather than reducing the acid.
The reference is 'Stanley Benedict - Notes on the Preparation of Glyoxylic Acid'. If there were a way to separate magnesium oxalate from glyoxylate
then you could test to see what sort of % gets converted but we couldn't find a way to do this. We can't recreate the original suggestion from the
paper that the product solution gives "no trace of oxalate".
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Waffles SS
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Glyoxylic acid is unstable compound and has different odor than most of aldehydes.it has yellow color and density of 1.3
It use as 50% solution.
Concentrating of it under vacuum and below 60c lead to precipitation of Glyoxylic acid monohydrate(above 60c it will decompose)
Neutralization of it should be done with carbonate or cold dilute base otherwise Cannizzaro reaction happen and most of glyoxylic acid decompose.
Testing method of glyoxylic and oxalic acid by titration:
| Quote: |
CONTENT OF Glyoxylic acid(GA) (Testing Method)
Take 0.5gm Sample in a 100 measuring flask, constant volume.Take 10ml of this to the Iodine flask, add 10ml 1.0mol/l NaOH. Shake well and Waiting
30mins. Then add 25ml 0.05mol/l I2, wait another half an hour,then add 20ml 0.5mol/l H2SO4, using starch as indicator, and titration with 0.1mol/l
Na2S2O3, until the solution from blue to colorlessness.Meanwhile, do the Blank experiment(V0)
Calculation:
GA(%) = [(V0-V1) ×C×3.7] ×100%/0.1×G
V1 = Volume of 0.1mol/l Na2S2O3 for the sample test
V0 = Volume of 0.1mol/l Na2S2O3 for the blank test
C= Factor of 0.1mol/L Na2S2O3
G= Wt. of sample
3.7 is the gram-equivalent weight of Glyoxylic Acid
CONTENT OF oxalic acid(OA) (Testing Method)
Take 5.0gm of sample in a 100ml beaker, add 50ml DD water,drop (1:1) Ammonia, until the PH reaches 5-6. Then add CaCl2 until deposit appears, Stir
continuously, then leave it for 120 mins under room temperature for filtration, wash up until no Cl- left. Then put the deposit with the filter paper
to a 250ml beaker, add 50ml (8+92) H2SO4, using standard KMnO4 for titration. Heat to 65 degree when it’s almost end, and keep dropping until
solution become light pink and stay for 30 secs.
Calculation:
OA%=V×C×4.502×100%/M
V- Volume of KMnO4
C- Factor of KMnO4
M- Wt. of sample
4.502 is the gram-equivalent weight of Oxalic Acid
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[Edited on 13-6-2016 by Waffles SS]
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morsagh
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Hi, today i didn´t have enought time to do titration, but i tried reaction of oxalic acid with magnesium according to chemplayer, filtred magnanese
oxalate off and added solution to fehling, (made testing sample with oxalic acid just for sure) and the test was positive. I tried adding solution to
iodine-NaOH solution and waited for 5 minutes, after which i acidified it (turned yellow quite like diluted iodine) but after addition of strach,
there was no blue color so again test was positive for aldehyde.
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morsagh
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And chemplayer, it should be easy to separate oxalic acid by adding some weak base like K2CO3 and than CaCl2 (until precipitating stops) to
precipitate all oxalic acid by filtring off calcium oxalate. You should end up with solution of pottasium glyoxylate
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gravityzero
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If anyone cares to shed a little more light on the separation technique.
Let's say one attempted electrolysis of oxalic acid in dilute sulfuric acid, which is a known method for producing glyoxylic acid.
How would one purify the resulting glyoxylic acid?
One book I read says to add barium hydroxide to precipitate the sulfuric acid and remaining oxalic acid. I assume creating insoluble barium sulfate
and barium oxalate.
Then after filtering, it suggests to add calcium carbonate to precipitate out calcium glyoxylate.
My question is why barium glyoxylate isn't formed in the beginning, along with the other precipitates?
Could one not just distill the entire catholyte solution under heavy vacuum?
Water and glyoxylic acid should come over fairly close together, then the distillation is stopped, leaving behind oxalic acid and sulfuric acid.
Does anyone have any suggestions? Does this look about right?
The reason I mention heavy vacuum is glyoxylic acid decomposes at higher temps. Or so it appears in the literature.
[Edited on 9-8-2016 by gravityzero]
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Waffles SS
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Quote: Originally posted by gravityzero  | If anyone cares to shed a little more light on the separation technique.
Let's say one attempted electrolysis of oxalic acid in dilute sulfuric acid, which is a known method for producing glyoxylic acid.
How would one purify the resulting glyoxylic acid?
One book I read says to add barium hydroxide to precipitate the sulfuric acid and remaining oxalic acid. I assume creating insoluble barium sulfate
and barium oxalate.
Then after filtering, it suggests to add calcium carbonate to precipitate out calcium glyoxylate.
My question is why barium glyoxylate isn't formed in the beginning, along with the other precipitates?
Could one not just distill the entire catholyte solution under heavy vacuum?
Water and glyoxylic acid should come over fairly close together, then the distillation is stopped, leaving behind oxalic acid and sulfuric acid.
Does anyone have any suggestions? Does this look about right?
The reason I mention heavy vacuum is glyoxylic acid decomposes at higher temps. Or so it appears in the literature.
[Edited on 9-8-2016 by gravityzero] |
US3779876
US0798920
http://www.prepchem.com/synthesis-of-glyoxylic-acid/
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gravityzero
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Thanks Waffles SS.
I actually got more out of those articles than some of the previous ones I've read.
It would appear there are several options.
1 - Attempt to precipitate the sulfuric acid with a hydroxide. I still wonder why this doesn't react with the glyoxylic or oxalic acid, but this
isn't stated.
2 - Use hydrochloric acid instead, which should be easily removed to near completion via gentle evaporation. It could probably be done quicker using
a decent vacuum.
3 - Several articles mention not using a inorganic acid at all, albeit with low yields. This would not concern me as much, if it produced a clean
product.
I would like to achieve a clean product. This stuff appears to be expensive.
It would also be a cool way to produce glycolic acid, which is also expensive.
They have a use as facial peels apparently.
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clearly_not_atara
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Does glyoxylic acid give a bisulfite adduct? Couldn't this be used to purify it?
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Waffles SS
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You dont need to use H2SO4 or HCl.just use US3779876 workup in example 2
Barium glyoxylate is soluble in water but calcium salt is almost insoluble in cold water
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SHADYCHASE54
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I have UTFSE & UTFSE to no avail. I would have sworn someone posted a practical method to partially oxidate glyoxal into glyoxylic acid. The only
post that comes up is one that is based on a patent ref. Where a solution of glyoxal, hydrochloric acid and a small amount of 1-2% glyoxylic acid
reacts with conc. nitric acid; my issue is that as my target compound is glyoxylic acid I have none to add to start the reaction. Has someone
performed this reaction or a similar (H2O2) method? I would appreciate a reference or an expert with mole amounts reaction time etc.
Thanks in advance for any help your willing to provide.
Best regards.
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