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Author: Subject: Synthesis of malonic acid
vulture
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Synthesis of malonic acid

The usual synthesis route for malonic acid is chloroacetic acid + NaCN.

Now, chloroacetic acid isn't the problem, but NaCN is. A rather large quantity is required and ordering is not really an option. Synthesis of that much NaCN is rather cumbersome and the reagents need to be fairly pure.

Are there any other synthesis methods, maybe archaic ones?

Doesn't matter if the yield is low and the reagents are cheap and/or easily available.

Before you say anything, the malonic acid is required for an oscillating reaction.

If I'd were to use it for barbiturates, I'd just buy it (it's bloody expensive) because the profit would easily cover the expense.

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Marvin
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I dont have much and IVe been looking for a good way for a long time. I want to try the BZ reaction myself, though I think ferroin will be more of a problem.

Only method that looks like it might be doable at home, is oxidation of malic acid with chromic acid mixtures. Its possible nitric acid might work though it could go furthur to oxalic acid, etc.

Still searching for a good way. Decomposition of barbituric acid, oxidation of b-propylene glycol etc are all unlikley at home.
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Just inital speculation thumbing through my chemical encyclopedia (un complicated by essentials such as seperation of products and reaction conditions)

Glycerol and magnesium sulfate react to form acrolein, this can be reacted to produce the 1,3-propylene glycol (I don't know excatly how it's done, under the entry for 1,3-propylene glycol it lists acrolein as what trimethylene glycol is derived from.) Then from here all you need is a good oxidizing agent, acidic dichromate, alkaline permanganate, etc. Thereby malonic acid is obtained.

Jeeze..... so much information is lacking from a complete picture, although glycerol, magnesium sulfate, and an oxidizing agent are easy starting materials to aquire so far...

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vulture
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Oi, it seems that propane-1,3-diol is even more expensive than malonic acid itself!

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Geomancer
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The glycerol->1,3 propanediol routes are what springs to mind. Unfortunately, glycerol seems to have a strong tendancy to dehydrate to acrolein, rather than making a nice long stop at the monodehydrated compound. Why is this? There might be a route there, though; trap the aldehyde as an EG acetal or something. Rehydrating acrolein seems roundabout.
Some bacteria are perfectly happy doing this conversion. It's being studied industrially apropos some new polyesters.
Turel
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NaCN

Hoffman Isonitrile Synthesis would work.

Aqueous ammonia and sodium hydroxide will react with chloroform to produce aqueous sodium cyanide and sodium chloride. It may require the aid of phase transfer catalysis, as chloroform and water are immiscible.

-T
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I think it would need the assistance of the Almighty to work very well. OTOH you can always see if there is a market for the formic acid that is produced by the hydrolysis of chloroform. If there is, then you can sell it and buy malonic acid.

Can you decarboxylate malic acid to give hydroxy propanoic acid then oxidise that to malonic acid?
I have a vague recollection that something like that is where malonic acid gets its name from. (Indirectly, from the latin name for apples)
Polverone
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funny you should mention that

I tried using this method to produce NaCN some time ago, and tried again just recently. I didn't use a PTC, just added enough 95% ethanol so that everything went into solution. I heated an excess of NaOH with chloroform and clear household ammonia solution (all added to the EtOH) for an hour or so. It formed a light-yellow solution with a foul smell. The liquid failed to give a positive Prussian blue test. Did the ethanol interfere?

Vulture: why is homemade NaCN a problem? The high-temperature route that uses sodium cyanate as an intermediate, which has been discussed here before, is easy to perform. The main impurity in your NaCN made this way will be Na2CO3, and that shouldn't interfere with your synthesis.

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Polverone
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further results

I tried the isonitrile method again, two different ways. In the first, I tried using some swimming pool "winter algaecide" that listed "ACTIVE INGREDIENT: Alkyl (C<sub>14</sub>, 58%; C<sub>16</sub>, 28%; C<sub>12</sub>, 14%) dimethyl benzyl ammonium chloride ... 40%" as a phase transfer catalyst. Where the liquid contacted a bit of solid NaOH clinging to the neck of the flask, it instantly darkened and eventually became almost black. In the liquid mixture of NaOH, CHCl3, and aqueous ammonia (no EtOH this time), it rapidly turned brown with agitation. The brown-gunk was selectively concentrated in the blobs of chloroform sitting in the flask. After moderate heating for 4 hours or so, the chloroform blobs had disappeared. There was considerable brown-black gunk floating on the surface. There was an unpleasant scent like when I ran the experiment with EtOH cosolvent, but it wasn't as strong.

The unpurified liquid (still containing gunk) was mixed with acidified Fe(II)/(III), and gave a handsome Prussian blue.

I repeated the experiment, but used no cosolvent and no PTC. The chloroform took considerably longer to disappear (and I think it mostly disappeared by volatilization from the flask). Only the scents of ammonia and chloroform were noted in the final liquid. It grew slightly cloudy but there was no discoloration. I failed to obtain Prussian blue when the liquid was put to the test.

So, at least when using dilute (household) aqueous ammonia, it appears that a PTC is very helpful, EtOH cosolvent somehow interferes to give something else, and chloroform reacts very little without PTC or cosolvent. It also appears that my expedient PTC choice was not very good, because it gives rise to a bunch of degradation junk. Perhaps a simpler PTC would not degrade.

Actually, I've controlled the variables so loosely, it's impossible to determine for sure what the sources of my successes and failures were. Still, I didn't want the details of my crude and imperfect trials to fade from memory. This was also exciting because it's the first time I've been able to see the effects (or apparent effects) of a PTC.

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Turel
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That PTCs only have effect during strong agitation or stirring, not while static. They aid homogenization, not facilitate it alone.

Very interesting results.

[Edited on 4-3-2004 by Turel]
Polverone
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Really?

I was hand stirring/shaking it at frequent intervals for an hour or so (I don't have any stirbars!) But my understanding was that PTCs aren't used to make the solution homogeneous, but to shuttle back and forth between the aqueous and nonaqueous phases, carrying the desired anion into the nonaqueous phase. I can see that this shuttling would be enhanced by greater contact area between the two phases, but I would expect some effect even if they remain placid. Is this not the case?

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Turel
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True

No, your description of the operation of PTCs is correct. However, as catalysts for two-phase solvated reactions, they are largely ineffective unless used in conjunction with strong agitation or stirring.

I have always been taught that PTCs are worthless while static. The polar PTCs are themselves attracted to the polar solution, so net static diffusion is minimal, and never reaches anything close to the high degree of diffusion created under agitation.

Can you make a stirrer out of plastic or steel? Rapid uneven stirring works best for solvents that are not ruined by aeration, as the cavitation produced causes a very high degree of ion diffusion from the PTC into the nonpolar solvent.

I have never done an isonitrile synthesis myself, I have only read about them. But I have read about them in many places, and I got the drift that they were highly effective in organic synthesis. In this reaction, iso-hydrogen cyanide would be the product, and it is very unstable, most especially in polar solution, where H2O easily removes hydrogen from electropositive nitrogen. The result is a solvated cyanide ion.

Since only 1 in 8 people on average can detect the smell of cyanide, I would not recommend smelling it as a test for it's presence. I too find it disheartening to hear of the failure of Prussian blue. Ethanol should not interfere.

-T
Polverone
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Thank you for the discussion of PTC use. My practical organic books are from before the common use of PTCs, and theory-oriented texts usually omit important practical details.

I will see what sort of stirrer I can improvise. I would hope magnetic stirring would work, if not be ideal, since I already have a magnetic stirrer and just need some stirbars for it... In this environment, I might be able to get away with using a paperclip, since it shouldn't be very corrosive to iron.

Summary of results, in case I expressed it unclearly before: Prussian blue test was positive with the batch using PTC, negative with ethanol cosolvent, negative with "plain" mix using no cosolvent and no PTC.

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Magpie
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This is an old thread concerning the synthesis of malonic acid but vulture's question was left unresolved.
 Quote: Are there any other synthesis methods, maybe archaic ones?

I also wanted to know the answer so tracked down an archaic reference, ie, that of von Dessaignes in Ann., 107, p.251, 1858, "Ueber eine durch Oxydation der Aepfelsaure erhaltene Saure." A friend was kind enough to provide me a summary in english.

The article provided no quantities which made my synthesis attempts difficult. Here's how it went on my 2nd attempt:

1. Dessaignes: oxidize the aqueous malic acid at room temperature with acidic potassium dichromate. Me: mix 50mL DI water, 1mL con H2SO4, 1.34g Na2Cr2O7*2H2O, and 0.91g malic acid in a 250 mL beaker. Temperature max = 16C. Noted some small amount of bubbling which I assumed was CO2. Color was green with hint of orange. pH = 1-2. Brought temperature up to 33C using a water bath.

2. Dessaignes: add an excess of milk of lime, filter, and save the filtrate . Me: added NaOH to pH = 9 as I was afraid of Ca malonate precipitation*; filtered, centrifuged filtrate, and saved final centrifugate.

3. Dessaignes: Add lead acetate to precipitate the malonic acid. Me: Added a total of 6.7g Pb(OAc)2*3H2O (which seems like too much) to the 80 ml of centrifugate. Color was pea soup green at first but eventually supernate became almost clear with a purple tint when all Pb(OAc)2 added. pH =6.

4. Dessaignes: Add dilute HNO3 but only enough to dissolve the malonic acid leaving the rest of the ppt. Me: Added 6N HNO3 to pH = 2 (about 9 mL).

5. Dessaignes: Filter, saving the filtrate. Me: filtered discarding the green ppt and keeping the dark blue tinted filtrate.

6. Dessaignes: Add ammonia to "3/4 saturation." Pb malonate crystals will reform. Me: added ammonium hydroxide to pH=8. Never got any crystals even after reducing the filtrate volume by at least half.

*(milk of lime [Ca(OH)2] was used on the 1st attempt with same results, ie, ultimately no crystals of Pb malonate.)

I'm sorry if this long dissertation has become tedious but I thought that only through providing all detail could I hope for any constructive suggestions. Although I have spent a lot of energy on this already I'd be willing to do more experimentation if I could get some encouraging suggestions about what to do differently. Your discussion and suggestions are welcomed.

The single most important condition for a successful synthesis is good mixing - Nicodem
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 Quote: Originally posted by Polverone I tried using this method to produce NaCN some time ago, and tried again just recently. I didn't use a PTC, just added enough 95% ethanol so that everything went into solution. I heated an excess of NaOH with chloroform and clear household ammonia solution (all added to the EtOH) for an hour or so. It formed a light-yellow solution with a foul smell. The liquid failed to give a positive Prussian blue test. Did the ethanol interfere?

I got that several times and it really made me mad to waste a lot of my chemicals.

I got it to work once. Ethanol seems to be the culprit.

You probably know this, but water causes to formation of formate, and ethanol screws it up. What other solvents are good for this, preferbly OTC?

Sauron
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I have some malononitrile on hand but no malonic acid at present.

Malonic acid $43 250 g from Acros or$18/100 g

Malononitrile same source $70 500g so it is a bit cheaper. Maybe not enough to bother with for the effort of the -CN to -COOH transformation. 1,3-propanediol same source$48 250 ml

Acros is a Belgian outfit. Connected with Fisher in USA. Sell worldwide, I buy from them here.

There's a series of rxns in Org Syn that will get you where you want to go but I don't remember if they start with glycerol, or with acetone. If halogenation of glycerol not so bad but if s,3-dihaloacetone, very nasty stuff, vesicant, crosslinks DNA strands I bet just like sulfur or nitrogen mustards, sym-dichlorodiethyl ether or lewisite. Carcinogens, mutagens, evil in molecular form, A direct assault on the genome.
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I checked in Org,Syn. and unfortunately no prep of trimethylene glycol. The prepsgiven in references in their malonic acid prep include hydrochloric acid oxidation of malononitrile and a carboxylation of carbon suboxide - which does not seem very practicable unless you have a cylinder of that on hand.

If diethyl malonate is cheaper than the acid you might saponify that,

There is a prep of 1,3 dichloroacetone by dichromate oxidation of 1,3-glyceroldichlorohydrin. Abd a prep for that too. But then you will have to figure out how to get rid of that 2-OH group, then hydrolyze to the glycol then oxidize to the acid. Sounds like 5 steps from glycerin and one of then undocumented.

How much malonic acid do you need?
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There's an alternate route but no advantage as you are still starting from chloroacetic acid or sodium chloroacetate. First prepare sodium cyanoacetate from NaCN; liberate the free acid in hod with HCl. Esterify with 95% ethanol. Use the ethyl cyanoacetate to prepare cyanoacetamide. Condense the cyanoacetamide to malononitrile. The Org.Syn. procedures use either PCl5 or POCl3 for this. Treat malononitrile with conc HCl, and you have your malonic acid. The only economy I can suggest is that CC can replace the phosphorus chlorides in the amide to nitrile step. (Cyanuric chloride),)

I have zipped up the Org.Syn.pdf's and attached the zip file below. But I think you will be better off buying the malonic acid or maybe malononitrile rather than doing all this laborios prep work.
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 Quote: Originally posted by Polverone I will see what sort of stirrer I can improvise. I would hope magnetic stirring would work, if not be ideal, since I already have a magnetic stirrer and just need some stirbars for it... In this environment, I might be able to get away with using a paperclip, since it shouldn't be very corrosive to iron.

try the plastic coated paperclips and put a drop of super-glue (cyano acrylate) on each end.
it should work as a temporary fix

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Sauron
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Zip file attached

[Edited on 29-12-2006 by Sauron]

Attachment: malonic acid.zip (577kB)

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 Quote: Originally posted by Sauron There's an alternate route but no advantage as you are still starting from chloroacetic acid or sodium chloroacetate. First prepare sodium cyanoacetate from NaCN; liberate the free acid in hod with HCl. Esterify with 95% ethanol. Use the ethyl cyanoacetate to prepare cyanoacetamide. Condense the cyanoacetamide to malononitrile. The Org.Syn. procedures use either PCl5 or POCl3 for this. Treat malononitrile with conc HCl, and you have your malonic acid. The only economy I can suggest is that CC can replace the phosphorus chlorides in the amide to nitrile step. (Cyanuric chloride),)

Why so damn difficult? Why don't you just treat the cyanoacetic acid with HCl to get your malonic acid?

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Sauron
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Damed if I know. Don't kill the messenger, I am only reporting what I found in Org.Syn. The same procedure is in Vogel - as I am sure many have noticed he cribbed a lot from Org.Syn. and just changed to scale, usually downward.
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@Sauron: I would be happy with 100g of malonic acid or diethyl malonate. That Acros price is reasonable but as an individual I cannot buy from the major supply houses. The acid is available over the internet but the seller requires a DEA form. I don't have anything to hide but I don't want a knock on the door either. If I want this bad enough I can synthesize some NaCN and use the method in Vogel. The Dessaignes method is at first glance so attractive as it uses relatively safe reagents readily available.

I have a gut feeling that the Dessaignes method would work in the hands of a skilled old-school chemist. That's what makes this such an intriguing challenge.

The single most important condition for a successful synthesis is good mixing - Nicodem
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I suppose the concern is about clandestine barbiturate manufacture, but I was blissfully aware that there is any such these days. The only one around here addicted to barbiturates is my dog, he's an epileptic. And his vet prescribes those.

How about malononitrile? Same dilemna or no?

This really is a ridiculous situation. Do you have to put up a billboard and take out a newspaper ad that says THIS IS NOT A CLANDESTINE LAB?

Ever try talking to the concerned authorities (local, state, federal) and simply explaining that you are an amatuer experimental chemist and would like advice on how to proceed without sending out false alarms. Don't wait for a knock on the door. Invite them. If they see you aren't making drugs (or othings of concern like explosives or chemical weapons, then they will lose all interest. Worth a try? Assuming you an an upstanding citizen with roots in your community and no criminal record or radical affiliations. The DEA employs a lot of chemists, you know. There will be sympathetic souls around.

I dunno. It depends on where you live and what your situation is. I haven't lived in the US for two decades and am 10,000 miles away geographically. I can't judge.
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I have a feeling that the Dessaignes method is not a laboratory method for the preparation of malonic acid.
If I had gotten this german article if I was in need of malonic acid I would never have attempted this synthesis. It just screams out "This will end up in a mess and wasted chemicals".
I know other preparations from which I can say by looking at them that I'll never get them to work, even if I have all the chemicals and apparatus.

Tell me, what is this synthesis for which you need diethyl malonate? Maybe we can find another way to make the target compound without use of malonic acid.

It indeed is a stupid situation to be deprived of chemicals because of nonsensical laws (who makes clandestine barbiturates anyway?).
In those situations you have to remind yourself that you have nothing to hide and therefore can fill out any forms necessary for the procurement of the substances.
When i bought acetic anhydride I also had to fill out forms about my lab and especially what I intended to do with the chemical. I simply stated the truth (cinnamic acid, cumarin, acetylcellulose), and that worked.

If malonic acid is still your target, I'd investigate the manufacture of NaCN from commercial ferrocyanides. There are ways to do this without dealing with gaseous HCN:

Simple heating of ferro- or ferricanides with charcoal powder under exclusion of air (loosely stoppered test tube) furnishes a mixture whose only water- soluble compound is KCN.
However, most of the cyano groups in the ferrocyanide are lost as N2 in the process.
The best method is still the one with gaseous HCN.

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 Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Synthesis of malonic acid Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues