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ssdd
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Caffeine Synthesis
So I was looking for an interesting organic synthesis of sorts and thought that producing caffeine would be fun.
I know that dimethyl urea malonic acid are needed but I can't seem to find how to actually run the synthesis.
Anyone have anything that may help me out, or perhaps a better synthesis to run. (looking for anything involving neurochemistry)
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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The_Davster
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A lot easier than synthesizing it: https://sciencemadness.org/talk/viewthread.php?tid=2234
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ergoamide
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True that would be easier but not nearly as challenging and rewarding as synthing it. I'm very interested in this synthesis to so if anyone does have
some more info on it's synthesis i'd be keen.
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ssdd
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Yea I was thinking the same thing, the few times I have ran extractions I have found it to be not nearly as fun nor gratifying than making something
from the ground up.
I'll keep looking but a patent search seems not to have turned up much...
Thanks
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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Sauron
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Try Merck Index.
Synthesis: Fischer, Ach, Ber. 28, 2473, 3135 (1895); Gepner, Kreps, J. Gen. Chem. USSR 16, 179 (1946); Bredereck et al., Ber. 83, 201 (1950); Crippa,
Crippa, Farmaco Ed. Sci. 10, 616 (1955); Swidinsky, Baizer, U.S. pats. 2,785,162 and 2,785,163 (1957 to Quinine Chem. Works); Bredereck, Gotsmann,
Ber. 95, 1902 (1962).
Only the patents are readily accessible in English.
The Fischer and Ach prep is readily available, but in German.
In northern Thailand, adjacent to the Golden Triangle where most of the amphetamines are now produced in this region, caffeine is restricted as it is
in great demand as an adulterant for amphetamines. But in the rest of Thailand it is an unrestricted commodity.
This is not a difficult preparation.
Attached are both of the 1895 Fischer and Ach papers and both of the 1957 US patents, in a zip file.
[Edited on 13-8-2007 by Sauron]
Attachment: caffeine.zip (1.1MB)
This file has been downloaded 1220 times
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ssdd
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Thanks Sauron.
Searching around for general chemical uses or experiments with caffeine I found the following I felt was useful:
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When moistened with strong nitric acid, or dissolved in chlorine water and evaporated on a water-bath, it leaves a reddish-yellow residue which, in
contact with ammonia in solution or vapour, becomes purple from formation of murexide, the ammonia salt of purpuric acid. With potassium hydroxide the
colour is discharged. The aqueous solution is not precipitated by Mayer's solution (distinction from other alkaloids except theobromine). With
solution of silver nitrate it gives a granular crystalline precipitate; and with mercuric chloride, long needles soluble in hydrochloric acid.
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-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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Sauron
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The US patents are improvements on a procedure by Traube published in Ber. in 1900, rather than that of Fischer and Ach.
I will ost the Traube paper here shortly, as the patents do not explain the preparation of the starting compound, a nitrosouracil, while the Traube
article will doubtless do so, or anyway reference it.
Sometimes there is no escaping the German lit.
The starting point for this prep is 1,3-dimethyl-5,6-diaminouracil obtained from the corresponding 6-nitroso compound. Traube reduced the nitroso with
ammonium sulfide and then forylated the diamon product and cyclized it, thus obtaining theophylline, which merely needed to be methylated to obtain
caffeine.
The 1957 patents improved on Traube's prep by using 5% Pd/C and 80-85% formic acid on the nitroso compound to reductively formylate it to the
immediate precursor to theophylline in one step.
So much is very clear (if it works). So the question is how to build the substituted uracil in the first place. For that we must launch ourselves into
the German literature.
I do not believe this involves malonic acid. Dimethyl ureau, yes. So far it appears that the other component is syanoacetic acid. I will report back.
It sure helps to know that harnstoff is urea.
In the US patents one of the arrows in the rxn scheme is backwards. It should proceed from III to IV not from IV to III.
The Fischer articles elucidate the prep of the uracils.
Fischer employed PCl3 and this is going to be a potential problem for anyone following his route.
1,3-dimethylurea + malonic acid (or ester) gives you domethylbarbituric acid. I bet dollars to donuts this is a DEA Scheduled controlled substance.
End of the line!!
"But, Your Honor, I was only making caffeine!"
Unless I find a route that does not proceed through a barbiturate, I am going to lose all interest in this prep.
[Edited on 14-8-2007 by Sauron]
[Edited on 14-8-2007 by Sauron]
Attachment: Traube.pdf (1.2MB)
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ssdd
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Thanks for everything Sauron, I guess this one is off the list of things I can pull off. (seems barbiturates would be a bad thing to make as you
pointed out.) Though I find it interesting in the link between Caffeine and Barbiturates. (I guess since they both interfere with the brains functions
and the neurotransmitters?)
Anyway I'll move along to the Biochemistry section of the forum where there is some discussion of Caffeine extraction. (I found Caffeine Citrate while
reading there and it sounds very very easy to make.) If anyone has any suggestions of any other cool and legal  synthesis please inform me.
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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bio2
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......."1,2-dimethylurea + malonic acid (or ester) gives you domethylbarbituric acid. I bet dollars to donuts this is a DEA Scheduled controlled
substance.".......
No, but the non-active barbituric acid is a controlled substance so they would most likely view this as an analog
therefore controlled as well under the Analog/Designer Drug
Act.
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Sauron
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GOOD NEWS
Only Fischer & Ach went via barbituric acids.
Traube used dimethylurea and ethylcyanoacetate to prepare cyanoacetyl-N,N'-dimethylurea which cyclizes to 5-amino-1,3-dimethyluraciluracil
He then prepared the 6-nitroso derivative in the usual manner (sodium nitrite, HNO2 in situ) and reduced that to the 5,6-diamino derivative,
formylated the 6 position, dehydrated that to get to theophylline, and methylated that to get caffeine.
NO BARBITURATES ANYWHERE AROUND.
The US patent drops the ammonium sulfide reduction and eliminated an intermediate step, instead using reductive formylation with 5% Pd/C and 80-85%
formic acid which gives the 6-formyl product to then dehydrate to theophylline, hence to caffeine with MeI.
So you need
Dimethylurea (1,3-dimethylurea)
cyanoacetic acid (not the ester)
pyidine
phosphorus oxychloride
sodium ethoxide
sodium nitrite
acetic acid glscial
5% Pd/C
85% formic acid
dimethyl sulfate
I may have missed some details, am still studying Traube
Will come back and fill in, and add a reaction scheme drawn properly.
[Edited on 14-8-2007 by Sauron]
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Sauron
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The following is OCR'd out of the patent pdf. The procedure described goes straight from the dimethyl-4-amino-5-nitrosouracil to theophylline in one
pot, the catalyst is then filtered out for re-use, and the same pot used for the methylation step. The inventors used dimethyl sulfate rather than
methyl iodide as per Traube and did not specify the caustic. Traube used sodium ethoxide.
Example I.-Preparation of caffeine
A JTljxture of 100 g. of I monohydrate (.5 mole) and
950 cc. of water were stirred vigorously atroomtemperature.
A slurry of 4.00 g. of 5% palladium charcoal
in 50-cc. of water was added next and finally 90
cc. of 85% formic acid.·" The reaction is exothermic
and carbon dioxide is evolved. The temperature rises
to 33-40° (in about 1 hour). The mixture is then
heated slowly to 40-45 ° and kept at that ,ange until III
starts" to precipitate and most of I has disappeared (in
abotH 1 hour). The evolution of carbon dioxide abates.
The temperature is raised slowly to 75° (in about 1 and
~
hour) and kept there until the pink color of I has
completely disappeared and complete solution (except for
the catalyst) is obtained (in about 30 minutes); Then
the mixture is brought toboHing, diluted somewhat and
filtered to recover the catalyst for re-use. Strong caustic
is added to the filtrate to bring the pH to about
12-13. The solutionis boiled for one hour, cooled and
methylated with dimethylsulfate in the usual manner.
The pH is adjusted and the first crop of caffeinerecovered
from a volume of 1000 ml. The second crop is
recovered from about 250 m!. The combined weight of
these two crops, after drying .to constant weight at 110°
is 84.9 g. (87.3% based on n. The color is offcwhite
and the melting point is above 230° (can:.). The melting
point of caffeine given in the United States Pharmacopeia
XIV (1950) is 235 to 237.5°. Chloroform extraction
of the mother liquor yielded an additional quantity
of crude caffeine. Use of methylating agents other
than dimethylsulfate such as methyl chloride, methyl
iodide and the like, is also feasible. If desired, the process
may be interrupted to isolate the theophylline.
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Sauron
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And here is the overall reaction scheme. The nitrosouracil is compound I in the patent. All the steps to that are from Traube, q.v. All after that
are from the patent.
Traube's use of POCl3 as a condensing agent in the cyclization of cyanoacetydimethylurea may be a trouble spot for most of us. I will hunt up some
other uracil preps that are parallel and see if I can find a non CWC substitute.
NOTE: in the scheme below I mistakenly drew ethyl cyanoacetate rather than cyanoacetic acid. THIS IS WRONG. Traube used the free acid.
[Edited on 14-8-2007 by Sauron]
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ergoamide
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Thanks sauron i think i found my next project anyway. I'm surprised that caffiene is a common adulterant really. It and it's salts arent terribly
water soluble I thought. It's citrate salt which is the most soluble i thought and is only 40g/100mL i think.
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Sauron
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I am not an expert on abuse drugs but I think amphetamines are usually smoked in Thailand. The local term is yaa baa (crazy drug) whereas in the
Phillipines it is called shabu shabu.
Another common adulterant locally is strychnine, which complicates withdrawal significantly.
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ssdd
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Its not as bad a synthesis as I thought it would be. The issue now being how to obtain those chemicals. (perhaps wait till the fall till I get to
college and use their labs...)
But in the mean time while researching caffeine alot in the past few days, as ergoamide pointed out, some of the caffeine salts look like thy could be
fun and easy to make.
I will synthesize this at some point, just need those chemicals. (Or a way to make those...) Time for a search engine once more... 
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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Sauron
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I just corrected a mistake, cyanoacetic acid and not ethyl cyanoacetate is employed in the condensation with dimethylurea.
If it is any help you make cyanoacetic acid from chloroacetic acid and KCN or NaCN, and you can make your own chloroacetic acid by chlorinating
glacial acetic acid in sunlight in presence of one of the usual halogen carrier catalysts (like red P.) Chloroacetic acid is however pretty easy to
obtain.
The Pd/C can be reused. And you don't need much. 4 g of the 5% Pd?c on a half molar scale (100 g of starting material.)
So if you get 10 g of it and your mechanical losses are not too high you can get many runs out of it.
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ssdd
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Ok, well that eliminates one thing I would need to find, I know for a fact that I have access to all of the things needed to make chloroacetic acid,
and I'm sure theres some kind of cyanide around I can get... A trip to my old high schools lab and I am set. (The teacher will still let me in if I
wanted to make something. I knw they have all these things because I did the inventory on the room.  )
Have you tried this yet sauron, or intend to, I'd be interested in hearing how it turns out. (photos would be amazing.)
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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Sauron
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Org.Syn., as one might expect, has been very helpful. I found a prep of 4,5-diaminouracil from urea and ethyl chloroacetate that employs in-situ
sodium ethoxide (from Na metal and absolute ethanol) as condensing agent, to get to the 4-aminouracil, then sodium nitrite in AcOH to get the
5-nitroso compound, then Na2S2O4 to make the 4,5-diaminouracil.
Just omit the last step to get your starting material for the patent procedure and of course start with dimethylurea instead or urea.
No POCl3 around.
Do not let the structure throw you. That is just the enol form of uracil, a tautomer, which cannot form when the urea nitrogens are substituted. This
uracil is the same as the substituted pyrimidine shown in Traube, and the uracil shown in patent. Compare.
[Edited on 14-8-2007 by Sauron]
Attachment: CV4P0247.pdf (140kB)
This file has been downloaded 1424 times
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Sauron
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And here is prep of ethyl cyanoacetate (and cyanoacetic acid) starting with chloroacetic acid, which is made into sodium chloroacetate, metathesized
to sodium cyanoacetate, the acid liberated and optionally esterified.
You can save a step by obtaining sodium chloroacetate rather than chloroacetic acid
[Edited on 14-8-2007 by Sauron]
Attachment: CV1P0254.pdf (124kB)
This file has been downloaded 1805 times
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ssdd
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I think dealing with chloroacetic acid seems simpler in the end, it is a simpler prep and seems like less steps when you look at the prep for the
sodium chloroacetate.
But then again being I am learning a good deal in just reading this stuff I may have misread something.
Sauron thanks again, learning quite a bit from you.
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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Sauron
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IIRC it is necessary to convert chloroacetic acid to the salt, prior to treating with alkili cyanide. You can't treat the acid directly with the
cyanide. My suggestion was to buy sodium chloroacetate rather than prepare it. Or just buy cyanoacetic acid or ethyl cyanoacetate and skip the whole
drill. Otherwise use a good hood, chloroacetic acid is hazardous, as a cyanides. Wear gloves and goggles.
I pulled up two JACS articles referenced from the Org.Syn. paper on diamouracil. Between those three there is a lot of detailed description of the
reaction of dimethylurea and ethyl cyanoacetate using Na and EtOH to make NaOEt in situ to condense them. Be careful with the sodium.
The nitroso compound forms rapidly (almost instantly) and the precipitate is voluminous and stirrer may need to be stopped. Use an overhead stirrer as
a magnetic one won't hack this. A heavy duty overhead stirrer with a SS or teflonn shart (unbreakable) will be preferable to a pyrex shaft, if these
are available. If the motor won't turn even at low speed (higher torque) turn it off. The JACS articles describe what to do.
You will not be using the hydrosulfite reduction, but proceeding directly to the Pd/C reductive formylation and the conversion to theophylline.
According to the patent those are about 5 hrs worth of procedures.
If for some reason the patent does not work (this happens!) you have several alternative reductions to try:
Ammonium sulfide (Fischer/Ach, and Traube)
Sodium hydrosulfite (Org.Syn. and references)
others referenced from patent
And then formylation and dehydration stepwise.
I suppose it is worth emphasizing that the initial formation of the uracil (pyrimidine) is a variant of the classical active methylene reactions
(acetoacetic ester, malonic ester.) Cyanoacetic ester is in same class. You might care to review the mechanism, so that you are proceeding with
understanding of the steps, if you are not already well familiar with this kind of reaction.
You mentioned earlier being surprised at the connection between caffeine and the barbirurates structurally. But this is often the case. Nicotine is
another example, being closely akin to the vitamin Niacin (nicotinamide). Powerful medicines and powerful poisons alike are often structurally close
to some vital and necessary benevolent compound.
Just as an example, the cancer chmotherapeutics are mostly mofifications of nitrogen mustards - deadly chemical warfare agents. It's an ill wind that
blows no good. The CW agents came first.
The uracil ring is a biologically important one, main portion of uridine, the nucleoside and is also the parent of 5FU, a potent anticancer drug,
5-fluorouracil.
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Sauron
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Just a short note on nomenclature
Some of the lit. on this prep refers to the intermediates as substitutes pyrimidines and some as substituted uracils. While these are the same
structure they are numbered differently and to those not familiar with both heterocyclic ring numbering and the conventions of biochemistry and
molecular biology this can be a little confusing.
Pyrimidines are numbered from a nitrogen and the numbering proceeds so that the second ring nitrogen has the lowest possible number (3 not 5). Thus
the cyclized condensation product of dimethyl urea and ethyl cyanoacetate is according to IUPAC
6-amino-1,3-dimethyl-1H-pyrimidine-2,4-dione.
Uracil, a purine base, is numbered not as a heterocycle but from the first carbonyl carbon which is usually drawn at the 12 o'clock position, and
numbering proceeds so that the second carbonyl is 3 not 5
So our compound is named
5-amino-2,4-dimethyluracil
They are the same compound.
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ssdd
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OK so I am gona see if I can manage to work out exactly what steps there are in this synth... I'll post back later with results...
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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Sauron
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I found a different route which is interesting but the yields are poor.
While uracil is usually obtained by hydrolysis of nucleic acids, it can be synthesized from urea and maleic acid catalyzed by sulfuric acid or
polyphosphoric acid. The yield is 20%
Substitute 1,3-dimethylurea and you have dimethyluracil.
Nitrate that with fuming nitric acid (d 1.5) and you have 6-nitro-1,3-dimethyluacil which reduced to the 6-aminodimethyluracil we are already familiar
with.
Hit that with sodium nitrate and fou have the 5-nitroso-6-aminodimethyluracil, rose red color.
From there proceed as per patent cited upthread.
The cyanoacetyldimethylurea route is better. But it is nice to have alternatives.
I will add references to this tomorrow, time for some sleep now.
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ssdd
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Alright, so I've reread everything that has been posted so far and heres my guess as to what needs to be done, let me know how on track I am.
Step 1. Take 100g of nitrosouracil (produced by any method... I like the one that you just posted even with the low yields.) And mix this with ~950ml
of water.
2. Add to this a 5% mix of Pd/C slurry.
3. Next add the 90ml of Formic Acid.
4. When CO2 is done evolving raise the temperature to 75* C?
5. Filter the solution to recover the pd/c and raise the ph with NaOH to about 13.
6. Add dimethylsulfate and recover the caffeine. (raise the ph again and repeat this step.)
I think this is the base of which we are working off of, now as I read on and on you have provided some great shortcuts depending as to what I can get
my hands on.
Sauron, thank you thank you thank you... Its been a great learning experience over the ast few days working on this thread with you.
-ssdd
All that glitters may not be gold, but at least it contains free electrons.
-- John Desmond Baernal
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