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Author: Subject: Synthesis of malonic acid
jimmyboy
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[*] posted on 29-12-2006 at 15:09


if you can make malonic by oxidizing malic with dichromate then it should be possible to use permanganate as well - just mix it in a small quantity and keep at a very low temp (close to freezing) for a day or so - permanganate is much stronger - malonic decomposes to acetic acid with heat so it should be easy to figure out if you had any success
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[*] posted on 29-12-2006 at 16:13


In response to the one mentioning bZ oscillating reaction.

You know you do not need malonic acid for the BZ reaction. Other polycarboxylic acids will work too such as citric acid[this is pretty damn easy to come by]. However oxalic acid does not work at all. The color is not nearly as good as the malonic acid but as long as you can see the color change that is good enough.
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[*] posted on 29-12-2006 at 16:31


I'm also interested in malonic acid, I want it for the BZ oscillating reaction. (Which is very sensitive to Cl-, btw. I think you need fairly pure malonic acid, the 'pure enough for most purposes' in the Org Syn prep might not be pure enough for the BZ, don't know for sure.)

It seems stupid that they worry about barbituates, I also thought that nobody made these clandestinely. The legal issues are even more complicated for me, legally (Texas) I'd have to apply for a permit just to have malonic acid, and I don't like the idea of introducing my lab to the police. As someone said, that might not actually be a bad idea, but it still makes me uncomfortable.
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[*] posted on 29-12-2006 at 17:46


I second jimmyboy's suggestion. The oxidation of malic acid (by whatever means) is producing a keto-dicarboxylic acid as intermediate; in this C4 instance the carbonyl group is alpha to one end and beta to the other. So voila, decarboxylation, and you have your C3 dicarboxylic acid (malonic) instead of C4 dicarboxylic (malic is a hydroxysuccinic acid).

Where the old prep gets murky is in lack of clarity and in the (unnecessary IMO) complexity of the workup. It looks like all those steps and reagents are merely to quench the hexavalent chromium and isolate the acid. Why not look for a way to oxidize the malic acid in a nonaqueous solvent instead?

I realize I am not suggesting any specific solvent/oxidizer system but that is because one is impoverished by the wealth of choices. After all the malonic acid synthesis (from diethyl malonate and sodium ethoxide, to higher molecular weight compounds) also depends on just such a decarboxylation of a beta-carboxtlic acid. so why not review the workups normally used there and look for a method that eschews all that calcium hydroxide and lead acetate malarky?

Or, rather than making any salt of the malonic acid at all, why not just extract the malonic acid into an organic solvent that is impervious to the chromic acid or permanganate or whatever your choice of oxidizer is?

Then rotavap off the solvent.

Wash the product till it is completely free of traces of the chromic acid)
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Sauron
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[*] posted on 29-12-2006 at 17:47


Of course if you need a DEA form to buy malic acid too then you are back in the box.
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[*] posted on 29-12-2006 at 18:51


No, in the US malic acid is readily and cheaply available at health food stores and from some wine making suppliers.

Sauron I believe you have stated the correct mechanism and this is confirmed in my text by Fieser & Fieser. But I don't see where KMnO4 is an advantage over Na2Cr2O7, especially if you say that the dichromate is the milder oxidant. (Dessaignes specified room temperature and I never exceeded 33C. I didn't see as much CO2 evolution as I expected.)

Making the diethyl malonate per Vogel requires chloroacetic acid. Making this requires red P. So I'm screwed on that route.

Malonic acid esters are shown to be very useful for synthetic chemistry due to acidity at C2. I have an experimental procedure exploiting this. That is my only reason for wanting the diethyl malonate which I intended to make from malonic acid.

In reference to your understandable feelings about the authorities attitude toward home labs, well, that is just a fact of life in the US today. Twenty, or even ten years ago that would not have been the case. Early in my time on this forum I proposed the very thing you mentioned, ie, go directly to the local police and state your case. One forum member promptly said that that was a completely idiotic idea. I decided that he might very well have a good point. I have not heard of anyone in the US that has actually done this. Even if someone did get a favorable reception I would think that this is something entirely local and immediately subject to change. For that reason I have chosen to keep a low profile. I feel that even though home chemistry is not illegal in the US they would find a way to close me down if they chose.




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Sauron
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[*] posted on 29-12-2006 at 19:53


All right then. Form a small business, incorporate, get an EIDN with the IRS and a business license from your city and state as a research laboratory. Depending on your zoning situation you might not be able to do this in your home. But then again you might. I can't overemphasize that this is not a formula for setting up a drug lab as the DEA and the local police etc do check up on commercial labs; they can audit your lab and if you are making a scheduled substance or have made one previously chances are they can find enough trace of it to be a problem. Don't buy drug precursors (especially direct ones like phenylacetone) although sometimes depending on what LEGITIMATE work you are doing this is unavoidable. Explosives are a sticky issue. ATF will have to license you and approve storage and local and state authorities may well have their own requirements, Doing this in a residence is very likely to be incompatible under the law.

In short to be a legitimate lab you must behave as a legitimate lab.

If you behave like a clandestine lab then even if you aren't making drugs, or explosives, or worse, you will certainly be seen as a clandestine lab and you will always have problems with suppliers of equipment and chemicals. The govt has put the burden legally on lab supply houses to know who they are dealing with and to report any and all suspicious activity. In short every supplier is now an informer. If the feds find that a supplier sold to a drug lab and did not rat them out, the seller goes to jail. In some locations it gets worse as there are vigilante groups like CAMP going after drug operations.

So keep your nose clean.

If you can't sly under the radar, make sure you have a transponder with IFF (that's Identify Friend or Foe.)
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[*] posted on 29-12-2006 at 20:08


BTW red P is not mandatory for chlorination of acetic acid, it merely accelerates the rate of the chlorination. Direct chlorination is UV mediated so you need reliable sunlight or preferably a UV reactor. OR chlorinate with CuCl2 (see thread) or N-chlorosuccinimide, both of which monochlorinate the alpha position of carboxylic acids I think. NBS does for sure and bromoacetic acid would work just as well,


Furthermore chloroacetic acid is cheao and as far as I know unrestricted. (Am I wrong?)

Where I am neither malonic acid not diethyl malonate are restricted. I haven't bought any but have obtained quotes on the latter. I did buy malononitrile without the slightest hassle. So you might want to look into malononitrile and then you can treat it with conc hydrochloric acid to obtain malonic acid.
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[*] posted on 30-12-2006 at 04:56
I thought you could


could also use sulfur for this chlorination as it generated
chlorides of sulfur which then chlorinated the acid.




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[*] posted on 30-12-2006 at 07:33


You could use sodium carbonate and Nitrogen. Sodium carbonate can come from even a chemistry set and nitrogen can come from fertilizer. To form the compound, they obviously use covalent bonds, so you could probably use a method similar to electrolysis.



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[*] posted on 30-12-2006 at 15:41


Quote:
Originally posted by Sauron
(cut) Where I am neither malonic acid not diethyl malonate are restricted. I haven't bought any but have obtained quotes on the latter. I did buy malononitrile without the slightest hassle. So you might want to look into malononitrile and then you can treat it with conc hydrochloric acid to obtain malonic acid.

If you treated malononitrile (the nitrile of malonic = propanedicarboxylic acid, NC-CH2-CN ) with concentrated HCl to hydrolyse it to malonic acid, HOOC-CH2-COOH, the byproduct would be mostly NH4Cl which is left in solution; but there is the possibility of side-reactions involving some decomposition to form HCN and ClCN, which are volatile and highly poisonous.
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[*] posted on 30-12-2006 at 16:09


i just suggested permanganate because it is so much easier to acquire and should work ..

our freedoms to experiment in science in the US are all but gone in chemistry -- either you hide what you have and risk getting harrassed or arrested for your desire of knowledge or you annually pay the government a few grand that you dont have and face the same bs.. no wonder our backwards country is so far behind everyone else - we punish innovation with our laws - but i am getting off subject

has anyone actually tried to the dichromate route and seen the results?
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Sauron
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[*] posted on 30-12-2006 at 18:42


Malonic acid by rxn of malononitrile with HCl (Conc) is an Org.Syn. prep. Not something I dreamed up. Classic procedure. Checked and verified, annotated and with safety notes and references.

I think anyone competent would recognize that adding a nitrile to mineral acid might release HCN and therefore, this is a procedure to be done in a GOOD HOOD. ClCN less likely but same caution. GOOD HOOD. If you were to attempt this on a larger scale I would say GOOD HOOD, SCBA, and CAUSTIC SCRUBBER, the oversize scrubber interposed between the reaction flask and the hood exhaust.
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[*] posted on 31-12-2006 at 00:12


hmm yet another interesting route -- lets see - cyanoacetic acid + ammonia -> cyanoacetamide + phosphorus oxychloride -> malononitrile + HCL -> malonic acid + HCN

hmm i think thats right anyway

cyanoacetates can be found in superglues - solvents
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[*] posted on 31-12-2006 at 02:40


Superglue is an ester of cyanoacrylic acid not cyanoacetic acid. Methyl cyanoacrylate it I recall.
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[*] posted on 31-12-2006 at 03:45


Adding HCl to nitriles does not release any HCN at all.
I have done the hydrolysis of benzyl cyanide with H2SO4 and trust me, there was not the slightest bit of HCN smell. I even did it outside my fume hood.
What happens is that the C-N triple bond gets cleaved completely (hydrolysis) and the nitrogen ends up as ammonium ion. Neither the C nor the N atom does change oxidation state here.
Liberation of HCN would require C-C bond fission which will simply not happen because there is no oxidiser present.




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[*] posted on 31-12-2006 at 07:55


Quote:
Originally posted by Sauron
I second jimmyboy's suggestion. The oxidation of malic acid (by whatever means) is producing a keto-dicarboxylic acid as intermediate; in this C4 instance the carbonyl group is alpha to one end and beta to the other. So voila, decarboxylation, and you have your C3 dicarboxylic acid (malonic) instead of C4 dicarboxylic (malic is a hydroxysuccinic acid).

Where the old prep gets murky is in lack of clarity and in the (unnecessary IMO) complexity of the workup. It looks like all those steps and reagents are merely to quench the hexavalent chromium and isolate the acid. Why not look for a way to oxidize the malic acid in a nonaqueous solvent instead?

I realize I am not suggesting any specific solvent/oxidizer system but that is because one is impoverished by the wealth of choices. After all the malonic acid synthesis (from diethyl malonate and sodium ethoxide, to higher molecular weight compounds) also depends on just such a decarboxylation of a beta-carboxtlic acid. so why not review the workups normally used there and look for a method that eschews all that calcium hydroxide and lead acetate malarky?

Or, rather than making any salt of the malonic acid at all, why not just extract the malonic acid into an organic solvent that is impervious to the chromic acid or permanganate or whatever your choice of oxidizer is?

Then rotavap off the solvent.

Wash the product till it is completely free of traces of the chromic acid)


Check this out:
http://cgi.ebay.com/The-Fascinating-Oscillating-Kit-Kits_W0Q...
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[*] posted on 31-12-2006 at 13:01


Quote:
Originally posted by joeflsts
Check this out:
http://cgi.ebay.com/The-Fascinating-Oscillating-Kit-Kits_W0Q...


Tempting. I'm trying to decide how to deal with the fact that shipping would nearly double the cost ($10 to $18). Even 5g of malonic acid is a lot better than wat I got now.

BTW - I am thinking that permanganate oxidation of malic acid will yield only oxalic acid and not malonic acid.

My reasoning... (Forgive the fact that I don't know organic chem very well so I may be totally off.)

Malic acid structure: HOOC-CH2-CHOH-COOH
I think the alcohol group will first oxidize to ketone. (Not sure though.) My books describe the mechanism of KMnO4 oxidation as going through the enol form of the ketone, i.e.

Malic acid oxidized to ketone: HOOC-CH2-C(=O)-COOH
This might form the enols as:
A: HOOC-CH=C(-O)-COOH, or
B: HOOC-CH2-C(-O)=COOH
But B can't happen because the last (rightmost) carbon already has all four hands full with the acid group, and can't spare one to make the enol, so only A can happen.

KMnO4 then grabs onto the double-bonded enol carbons, and further mechanism breaks the chain there, turning both of the enol carbons into carboxylic acid groups, thus yielding:
HOOC-COOH and HOOC-COOH, i.e. two molecules of oxalic acid.

However, as soon as the new year passes, I hope to stop by my local brewing supplier, which I hope will have malic acid, and I will try oxidizing it, to see what happens.

Questions:
1- How can one distinguish oxalic from malonic acid? I think malonic will decarboxyate under heating, forming acetic acid (someone mentioned this already), while oxalic won't. That is one test, but I'd like more.

2 - In Magpie's prep, if malonic acid was formed in the first oxidation step, why wouldn't it precipitate with 'an excess of milk of lime' as calcium malonate?

[Edited on 31-12-2006 by pantone159]
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Sauron
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[*] posted on 31-12-2006 at 13:29


Better have a look at the behavior of beta-kto acids.

Furthermore, it is quite simple to distinguish between oxalic and malong acid.

Melting points. ALl you need is a Thiele tube, some melting-point capillaries, and mineral oil for medium. And a heat source. And patience. First you need to crystallize the acid and keep recrystallizing till you obtain a constant m.p.. Also you can obtain an authentic sample of each acid. If you mix small equal amounts of the product and the acid you want, if they are same acid the m.p. remains same, if they are different the m.p. will be lowered.

Derivatives: esters, amides, chlorides etc. Diethyl oxalate and diethyl malonate have different b.p.'s. The amides are usually solids. Oxalic acid forms oxalyl chloride with cyanuric chloride, this reaction fails for malonic acid.

This is first year organic practical lab stuff. See Vogel's book.

[Edited on 31-12-2006 by Sauron]
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[*] posted on 31-12-2006 at 14:29


Quote:
Originally posted by garage chemist
Adding HCl to nitriles does not release any HCN at all.
I have done the hydrolysis of benzyl cyanide with H2SO4 and trust me, there was not the slightest bit of HCN smell. I even did it outside my fume hood. What happens is that the C-N triple bond gets cleaved completely (hydrolysis) and the nitrogen ends up as ammonium ion. Neither the C nor the N atom does change oxidation state here. Liberation of HCN would require C-C bond fission which will simply not happen because there is no oxidiser present.

I would not be so sure, in view of a particular case in point. The compound with one less C than malonic acid, namely oxalic acid, (COOH)2, is fairly easily decomposable by heating to CO2 and H20, by C-C bond fission (which is why rhubarb, which contains it, has to be cooked before eating), because of the repulsion due to the two vicinal highly polar groups. The same would apply to a slightly lesser extent to the corresponding nitrile, which in fact is cyanogen, (CN)2, the thermal decomposition of which in the presence of HCl would certainly result in formation of some HCN (prussic acid) and ClCN (cyanogen chloride). So, although the repulsion of the polar groups would be significantly less in malononitrile, it is likely to be still sufficient for decomposition involving C-C bond rupture if the hydrolysis by HCl was done at a sufficiently high temperature.
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[*] posted on 31-12-2006 at 14:44


Quote:
Originally posted by Sauron
Melting points. ALl you need is a Thiele tube, some melting-point capillaries, and mineral oil for medium. And a heat source. And patience. First you need to crystallize the acid and keep recrystallizing till you obtain a constant m.p.. Also you can obtain an authentic sample of each acid. If you mix small equal amounts of the product and the acid you want, if they are same acid the m.p. remains same, if they are different the m.p. will be lowered.
[Edited on 31-12-2006 by Sauron]


All I currently lack is the Thiele tube, the capillaries, and the authentic malonic acid sample. (And possibly the patience :) )

However, I did decide to get one of those kits, and the seller also had a Thiele tube, so I added that, so I soon should have 2 of 3.

Another test, btw, for malonic acid vs oxalic acid ought to be if the oscillating reaction works or not.

P.S. Based on the ingredients list, the kit is probably the Briggs-Rauscher reaction (see Shakhashiri, Chemical Demonstrations, Vol 2, 7.1) with sulfamic acid substituted for sulfuric acid.


[Edited on 31-12-2006 by pantone159]
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[*] posted on 31-12-2006 at 15:38


Malonate and oxalate would both be precipitated with Ca++ and that is why I tried NaOH vs Dessaignes' milk of lime [Ca(OH)2]. Oxalate is especially insoluble. Dessaignes does say that oxalates are byproducts. This would be the advantage of using Ca++, ie, it would take them out. If I try this again I would use milk of lime but have enough volume to keep the slightly soluble malonate in solution.

Fieser & Fieser in Introduction to Organic Chemistry, 1957, p. 251 do say that the oxidation proceeds through the ketone and then elimination of the C=0 as CO2 to give malonic acid.

As a side note sugar beets (or beets in general) are supposed to be rich in Ca malonate, with the total organic acid content being around 2.6%. It sounds like another interesting (and time consuming :( ) challenge to try to isolate malonic acid from that source.

Edit:

I wanted mention that a really slick way to help identify an organic acid is through titration. By titrating you determine the molecular weight. ;)

[Edited on 1-1-2007 by Magpie]




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[*] posted on 31-12-2006 at 19:17


Malonic acid is soluble in Et2O

Oxalic acid (anhydrous) is only slightly soluble in Et2O

Malonic acid is soluble in water @20 C 1400 g/L

Oxalic acid (anhydrous) is soluble in water only 90 g/ @20 C.

Malonic acid melts at 130-135 C

Oxalic acid (anhydrous) sublimes at 101-157 C and melts at 185-198 C

There are other differences in physical and chemical characteristics.

(Acros tech data sheets q.v.)

See also Aldrich catalog, Merck Index, Vogel's chapter on dicarboxylic acids. Many other reference works. CRC Handbook.

Obviously these two are not at all difficult to distinguish from each other, without the need to resort to exotic solvents or derivatization.

I bet the crystalline structures are also distinctly different. I know what oxalic acid crystals look like. Cubic and translucent. Haven't seen any for about 40 y\s but it's a clear memory. Don't recall what malonic acid crystals look like but it will be in the Merck Index monograph.

On points like this it is best to forget Kantian pure reason and go for the facts.
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[*] posted on 31-12-2006 at 19:31


Merck Index 12th Ed:

Malonic acid: small crystals mp c.135 C with decomposition; sublimes in vacuo. 1 g dissolves in 0.6 ml water; in 2 ml alcohol; in 1.1 ml methanol; in 3 ml propanol; in 13 ml ether; in 7 ml pyridine.

Oxalic acid: crystallized from glacial acetic acid forms orthorhombic crystaks, the shape being pyramidal or elongated octahedra. Hygroscopic, mp 189.5 C (dec); sublimes best at 157 C.
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[*] posted on 1-1-2007 at 11:21


Quote:
Originally posted by Sauron
Malonic acid is soluble in water @20 C 1400 g/L

Oxalic acid (anhydrous) is soluble in water only 90 g/ @20 C.


Are you sure about these numbers? (I.e. a ratio of 15.6, not 1.56.) If so, then oxalic and malonic ought to be easily separable by dissolving in a limited amount of water, the malonic would dissolve but the oxalic not.
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