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Author: Subject: Potential uses of Citric Acid
UnintentionalChaos
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[*] posted on 4-5-2007 at 00:20


Dry method I can do, but I am just going to sleep here (4am) and have work in a disturbingly short number of hours. I probably won't be able to give it a go until Sunday since I am swamped with work at the moment.

Concerning "2." note that the esters react with aqueous ammonia. There is water present for breaking the ester bond at which point ammonia can come in and react. I doubt the process would proceed so easily with almost no water present to enable hydrolysis. Given that the reaction temp is directly at the decomposition point of urea, I imagine that the active reactant here is the ammonia and the urea is used solely because it can generate it in situ at an elevated temperature. Fluoresce under black light I assume? Excellent "titration" there. Fortunately I have a black light somewhere.




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[*] posted on 4-5-2007 at 01:51


No mention made of UV. Sunlight even indirectly ought to suffice (as it does for fluorscein.)

I think I will give this (dry method first) a go myself. Have citric, have NH4OH, have urea, and ammonium carbonate, so can try all three methods before moving on to the Aries process. Can't do the autoclave method till my Parr 4521 arrives, a coupld months by slow boat after truck from Michihan to SF CA.

Meanwhile will buy some ammonium citrate tribasic. Acros has dibasic, may settle for that. Also I want to try that "acetanhydrocitric acid" method, as well. I want to start to accumulate some citrazinic acid.

For one thing, I'd like to try the conversion of it to isonicotinic acid, which is by chlorinating the two hydroxyl groups then reducing them off. The original investigators uses phosphorus chlorides, I want to try my fave alternative reagent that someone thinks I mention too much - so I won't. :)^

[Edited on 4-5-2007 by Sauron]
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[*] posted on 4-5-2007 at 03:11


Phenolic OH groups can be reduced to hydrogens by distillation with zinc dust. Thus, phenol gives benzene when treated that way. If citrazinic acid can be reduced by zinc would have to be tried. Maybe the isonicotinic acid decarboxylates to pyridine in the process.



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Sauron
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[*] posted on 4-5-2007 at 05:30


Don't know about the Zn dust. However the two fellows who started all this in 1884 teach that citrazinic acid, chlorinated by two mols PCl5, is then stripped of those chlorines by reduction with aq I2 to give isonicotinic acid. The three relevant pages from Ber. are attached, the entire 20 page article being a bit ponderous. I will put it up on my 4-shared.com acct and post a link here if anyone wants the entire thing. File name Binder1.pdf but feel free to rename it to something more meaningful after you download it.

http://www.4shared.com/dir/2245331/5a78115f/sharing.html

Merck cites a later article I have not been able to obtain DOI for as yet.

Wibaut, Rec. Trav. Chim. 63, 141 (1944).

Same topic, 2,6-dichloroisonicotinic acid to isonicotinic acid.

It should not be lost on anyone that this opens up an OTC route from citric acid to isonipecotic acid - piperidine-4-carboxylic acid.


[Edited on 4-5-2007 by Sauron]

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smuv
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[*] posted on 4-5-2007 at 06:04


Garage Chemist, do you have a ref. for the removal of phenolic hydroxys? I would like to read more about it.
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Sauron
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[*] posted on 4-5-2007 at 07:38


I looked over the Aries patent again. If we are to believe it, then the polyols are indeed supposed to be inert solvents. The broad temperature range of 125-140 C is given but they teach for best results 130-133 C just as @UC said.

One thing that did strike me was scale.

I can easily run 1 mol ureau and 1 mol citric acid, as a dry melt, in a 1 L flask and maybe more than that. That's 210 g citric acid monohydrate or 192 g anhydrous, and 280 g urea. The urea is added in two stages, 180 g first and 100 g two hours later.

But if I proceed per Aries, I need 900 g solvent, that's a little more than 700 ml glycerol or c.800 ml ethylene glycol. For sure I'd need to run this in a 2L flask.

Therefore for a given setup size, even if Aries process works I am going to obtain same amount of citrazinic acid, even though the yield is twice as good for the Aries process.

If I run this in my 5L flask I can get 5-7 mols in there without exceeding 50% of capacity once melted. Assuming a 25% yield, which is conservative, that's 1.25 to 1.75 mols product per batch. Roughly200-275 g citrazinic acid.

To get same amount by Aries method in same setup I'd have to do it twice.

Or go to a 12 L flask and mantle. that I don't have and would need to buy.

Given that citric acid and urea are about as inexpensive as you can get, while citrazinic acid is (per Acros) $3+/gram, the dry method looks pretty good to me. Sometimes yield doesn' tell the whole story.

Now I'm going to examine the Pfizer patent and see how much I can process per batch in my 1 L Parr autoclave. The working capacity is about 650 ml.

The Pfizer patent teached reaction of conc aq ammonia with anhydrous citric acid or preferably ammonium citrate in a pressure vessel @140 to 150 C or higher for 18-36 hours. The ammonia is employed in large excess and in concentrations from standard 28% to 53% made by adding ammonia gas to the concentrated ammonia at 0 C.

When 28% ammonia is used yields are 20-30% which is no improvement over prior art. Only by employing higher concentrations and large excess at pressure and temperature and lver a long time compared to the dry method, are the improved yields obtained, and these are somewhat less than transparent since they include about 1/3 of propduct retained in mother liquor, and recoverable by reusing said liquors. Best isolated batch tields are about 40% and that is about same as the "acetanhydrocitric acid" method described in the Sell and Easterfield series in J.Chem.Soc.

In my Parr 4521 1 liter autoclave I can at best run the Pfizer process on a half molar basis obtaining maybe 30 g product. I'd need a cylinder of NH3 and a regulator. Ouch!

In short this is not the way to go for a bench scale prep.

Both patents contain food for thought though.

[Edited on 4-5-2007 by Sauron]
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[*] posted on 4-5-2007 at 08:34


Quote:
Potential uses of Citric Acid


So far nobody mentioned the obvious: The Pechini method.

Admittedly it's neither organic nor plant chemistry.
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Sauron
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[*] posted on 4-5-2007 at 21:44


As I was saying the dry distillation (solventless melt) seems to be the most practical lab scale preparative method for making citrazinic acid. Sometimes it's not the best yield that counts, it's how much you can get out of a rxn you can run in the equipment you have!

So let's consider our options

Citric acid monohydrtate and urea

Anhydrous citric acid and urea

Ammonium citrate and urea

Citric acid monohydrate with ammonium carbonate

Citric acid, anhydrous with ammonium carbonate

Ammonium citrate with ammonium carbonate

Let's revisit Messers Sell & Easterfield.

While the Aries patent employs 55% excess ureau in their solvated scheme, Sell and Easterfield recommend 200% excess urea (540 g total) per mol citric acid. Okay, urea is cheap. Yield of citrazinamide claimed is 25%. The reaction is conducted at 155-160 C and takes about two hours, this is substantially faster than the Aries patent. A modification I would propose trying is to start the melt with half the urea and then add the other half after about 60-90 minutes, then continue heating till the mixture is semisolid.

----------------------------

The methyl and ethyl citrate esters are solids and have high boiling points. Ethyl citrate boils at 294 C for example. I found a literature procedure using dry hydrogen chloride as catalyst.

Ullmann's says ordinary acid catalysts such as sulfuric and p-toluenesulfonic acids.



[Edited on 5-5-2007 by Sauron]
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[*] posted on 5-5-2007 at 21:26


Apologies for double post, previous one getting cumbersome and this is a significant tangent.

Found a J.Org.Chem article concerning derivs of isonicotinic acid, in which they employed the citrazinic acid prep (from methyl citrate) then chlorinated with POCl3 (not PCl5) to obtain the 2,6-dichloroisonicotinic acid, then knocked off one Cl with hydrazine hydrate and CuSO4 and proposed to treat that with KSH to obtain the 2-thiol, in order to react with iodine to make the sulphide as an experimental tuberculostat.

The POCl3 is much more easily prepared than PCl5. It can be made from P2O5 by either treating with oxaclyl chloride, or some suggest fucing with NaCl. (The latter suggestioin was from Gattermann).

References for the chlorination and for the dechlorination are provided therein and I have requested these three articles. This will complete the citric acid to isonicotinic acid preparative route, as an alternative to the permanganate oxidation of 4-picoline, which may not be so easily obtained by some.

The JOC article is attached.

[Edited on 6-5-2007 by Sauron]

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[*] posted on 20-5-2007 at 08:03


Here is an article (a fucking recent article) on the use of my very favouritest 'ghetto' style, oh so bloody OTC, reagent (shit, I am turning into Sauron) - trichloroisocyanuric acid for the esterification of carboxylic acids:

http://www.4shared.com/file/16312738/cfc4e930/Acylation_of_A...

I swear to god, I don't search for trichloroisocyanuric acid - I just seem to find the stuff whatever the fuck I search for, honest...:P

tup

PS For those wondering how this is on topic, at least one of Nicodem's articles refers to the reaction of ammonia with the methyl/alkyl ester of citric acid... Thus, a good way to get to that ester is provided in the article (although, whether it will work properly with a tricarboxylic monster like this is anyones guess)




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[*] posted on 20-5-2007 at 12:39


The rxn of ammonia with methyl or ethyl citrate to give citrazinic acid was popular in the first half of the last century but as of the mid 50s was largely supplanted by use of citric acid directly or by citric acid with urea in a polyol solvent.

So a new way to prepare citrate esters is sort of an answer to a question no one asked.

But thanks for the article. I am always interested in new things to do with TCCA and TCT.
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[*] posted on 31-7-2010 at 14:37
Citric acid reactions


I have big amount of citric acid and I want to do some experiments with it. I don't know much about organic chemistry, but I suppose that's the way of learning it. Are there some interesting experiments with it?
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[*] posted on 31-7-2010 at 16:37


using citric acid as a catalyst in HMTD production can be fun-
until you lose your fingers, that is.........
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[*] posted on 31-7-2010 at 23:09


Thanks for suggestion, though I am not interested in blowing my head currently :)
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[*] posted on 5-8-2010 at 07:04


Ummm, pentachloroacetone (see attached paper) and then either the 1,1,1-trifluoro-3,3,3-trichloroacetone (from completing the chlorination to the 1,1,1,3,3,3-hexachloroacetone & then fluorinating it) or 1,1,1-trifluoroacetone by dehalogenation and then fluorination (IIRC).

Cleavage of that (or better reaction of the the ketone with amino acids to give the N-trifluoroacetate) to trifluoroacetic acid.

[Edited on 5-8-2010 by un0me2]

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[*] posted on 21-10-2010 at 01:14


Is there something I can do in organic chemistry with citric acid? Maybe some useful product?
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[*] posted on 22-10-2010 at 08:51


I don't know if your question is serious or you are just trying to entertain us, but in case you haven't realized it, this very thread is all about that topic already. So start reading it from the first post onward.
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[*] posted on 22-10-2010 at 11:09


Well, I looked, but citrazinic acid looks like citric acid to me, nothing very special :(
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[*] posted on 23-10-2010 at 00:41


Quote: Originally posted by Random  
Well, I looked, but citrazinic acid looks like citric acid to me, nothing very special :(

If that is the case then you should perhaps change your hobby and find a better pastime more suitable to your needs.
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[*] posted on 25-10-2010 at 10:25


This hobby is interesting and I am not changing it, I just wanted to know if there were some other things to do with it..

Edit:

On BromicAcid's page I saw that citric acid can precipitate powdered nickel from it's water soluble salts:

Quote:

Nickel powder can be formed in a number of ways, most notably by the reduction of a soluble nickel salt in an aqueous medium by zinc powder or citric acid. Additionally it can be formed as is shown at left by the decomposition of nickel oxalate formed by the displacement reaction between sodium oxalate and a soluble nickel salt.


Is this true and can I precipitate some other metals with citric acid from their water soluble salts too like zinc?


[Edited on 25-10-2010 by Random]
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[*] posted on 28-2-2011 at 07:39


I now got urea and learned actually what can be done with citrazinic.

I want to do this reaction:

citric acid + urea --heat--> citrazinic acid --hoffman degradation--> isonicotinic acid --decarboxylation--> pyridine

I would like to perform it on test tube scale, just to see how the preparation is possible and also to see how pyridine can smell bad :D
Also I would like to learn some practical chemistry with that too.

Now, does someone know what should I do, how much urea to use and citric acid? If I would do it on test tube scale using candle and 2 grams of each substance, how long would I need to heat it? Because citric acid could decompose.

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[*] posted on 28-2-2011 at 07:59


Quote: Originally posted by Random  
I now got urea and learned actually what can be done with citrazinic.

I want to do this reaction:

citric acid + urea --heat--> citrazinic acid --hoffman degradation--> isonicotinic acid --decarboxylation--> pyridine

I would like to perform it on test tube scale, just to see how the preparation is possible and also to see how pyridine can smell bad :D
Also I would like to learn some practical chemistry with that too.

Now, does someone know what should I do, how much urea to use and citric acid? If I would do it on test tube scale using candle and 2 grams of each substance, how long would I need to heat it? Because citric acid could decompose.



Citrazinic acid is actually 2,6-dihydroxy-4-pyridinecarboxylic acid. Hofmann rearrangement on citrazinic acid would do nothing (although the nitrogen is formally an imide so maybe something would happen to the ring). Hofmann rearrangement of the citrizinamide would give 2,6-dihydroxy-4-aminopyridine. The hydroxyls will basically be impossible to remove just like you'd be hard pressed to turn phenol back to benzene.




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'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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[*] posted on 28-2-2011 at 08:19


Oh yes, I forgot that to make isonicotinic I need POCl3 and then reduce that with hydrazine.

Also maybe by decarboxylation of citrazinic acid we could get 2,6-Dihydroxypyridine. By the way, what would we get by decarboxylation of citric acid? Maybe we could make some other organic compounds from 2,6-Dihydroxypyridine.

But anyway, I want to make citrazinic acid, because I know I will be able to do something with it.
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[*] posted on 28-2-2011 at 10:40


This is a bit late, but citric acid is also an alternative to hydrazine as a reducing agent for graphite oxide. If you want to make some diy graphene paper or try and jury-rig an old inkjet to make printable circuits.

See:

"Environmentally friendly approaches toward the mass production of processable graphene from graphite oxide"

J. I. Paredes, S. Villar-Rodil, M. J. Fernández-Merino, L. Guardia, A. Martínez-Alonso and J. M. D. Tascón

J. Mater. Chem., 2011, 21, 298-306
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[*] posted on 27-7-2011 at 03:47


I did the experiment yesterday. Into the test tube I put equal amounts of citric acid and urea and then I heated that test tube using candle. Soon as it melted the mixture started producing gas, after some time I observed very weak blue color in the previously colorless melt. Then I left it heat even more as It turned to blood red-brown melt that If I remember correctly became solid. When it cooled, half of the test tube was filled with solid sticky mass that on the sides was green, while inside was blood red-brown color. I was slowly filling the test tube with NaHCO3 solution and it dissolved the residue slowly (some gas, maybe CO2 was also slowly produced). Then I wanted to precipitate that with vinegar, but with excess vinegar added the solution was already 150mL so it looks citrazinic acid was dissolved. It was left to evaporate in hope some citrazinic acid will precipitate, further results will be reported.
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