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turd
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Formylation of para-methoxyphenol: failure due to diformylation
Let me interrupt your silly bickering with some honest cooking! Dilettante at work. 
Introduction
2C-B (http://www.erowid.org/library/books_online/pihkal/pihkal020....), one of Shulgin's magical half-dozen, is a phenethylamine with dramatic visual
effects. Due to its short duration and manageability, it is highly recommended for interested beginner psychonauts.
2-hydroxy-5-methoxy-benzaldehyde / 5-methoxy-salicylaldehyde is a key-precursor for the synthesis of 2C-B from OTC materials, necessary due to silly
social restrictions. Klute brought to our attention a high yielding Mg-mediated formylation reaction (https://www.sciencemadness.org/whisper/viewthread.php?tid=10...). The method has been succesfully applied for the synthesis of the
5-ethoxy-analogue by Ullmann: https://www.sciencemadness.org/whisper/viewthread.php?tid=12... (and other postings in this thread). The literature mentions near quantitative
yields for this reaction (Org. Biomol. Chem. 2483–2495 (2004)). Yet, some care has to be taken as the following failure demonstrates:
Experimental
80 ml MeOH (straight out of bottle) and 7.4 g Mg strips were stirred under exclusion of moisture using a "bubbler". The Mg showed serious signs of
corrosion. To start the reaction, three small I2 crystals had to be added and gentle heat had to be applied. Once the reaction started, heat was
removed. After evolution of H2 stopped, the flask was stoppered and left standing over night. There was lots of black crap from oxidized Mg.
The next day, 62 g p-methoxy-phenol was dissolved in 180 ml warm degassed toluene (straight out of the bottle).
The next day, spectacular crystals had formed, which were redisolved by applying gentle heat. The solution was added to the Mg(MeO)2 slush with
stirring and moisture protection (dark green solution). Additional 100 ml degassed toluene were added. The reaction was refluxed for 15 min
(white/grey precipitate) and the condenser replaced by a distillation bridge. 50 g of ground paraformaldehyde (directly out of bottle) were added over
the course of 1h30, while distilling off a MeOH/toluene azeotrope. At the end of the addition the internal temperature had risen to 85°C. The
reaction was then heated strongly to reach an internal temperature of 95°C in 15 min (Don't do that, see discussion below!!).
The reaction was cooled to RT and 400 ml 14% H2SO4 were added and stirred for 15 min. This is usually the nicest part of the reaction - weirdly the
green part was not observed. The reaction was extracted twice with toluene, the organics washed thrice with H2O (the last washing produced a nasty
emulsion which was broken by adding NaCl) and dried over Na2SO4. In total 400 ml of organic phase were obtained.
The volatiles were removed under vacuum and the residue distilled at reduced pressure. The first fraction distilled at 105-110°C. A yellow, intensely
staining oil with melting point below room temperature was obtained (spectacular yellow crystals in the freezer). The distillation was stopped when
the temperature suddenly shot up to >150°C. A few drops of the high temperature fraction were collected, which spontaneously crystallized.
The first fraction is probably the desired 5-methoxy-salicylaldehyde, 50 g (~66%), analytics not yet performed.
The second fraction was unambiguously identified as the diformylated product! There is a truckload of this stuff in the distilling flask! It
crystallizes and seems to be relatively pure. If it weren't for that diformylation, yields must be close to quantitative!
Discussion
1) p-methoxy-phenol is reactive - don't heat the sucker, what a shame! What a waste!
2) The literature gives widely varying melting points for 5-methoxy-salicylaldehyde. My putative product certainly melts below RT. Maybe there's an
azeotrope or something. The 5-ethoxy analogue was described as solid by Ullmann and I would expect the 5-methoxy to have a higher mp.
3) Argh! I'm pissed.
Edit: Fixed silly typo in title and in text.
[Edited on 23-3-2012 by turd]
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Nicodem
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Thank you for sharing your experience.
Unambiguously identified as in measuring its mp or some other type of characterization? Or unambiguously because you can't think of any other
possibility? Diformylation of phenols can usually be performed with the modified Duff reaction in trifluoroacetic acid. I did not check, but I can't
remember seeing it done with the Mg-mediated formylation with formaldehyde. It would be quite interesting though, if it would be possible and
effective. 2,6-Diformylphenols are of interest for the synthesis of the calixarenes and related compounds.
PS: 5-Methoxysalicylaldehyde is a liquid at room temperature. There are some erroneous mp reports in the literature which cause confusion.
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turd
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Melting point would be very ambiguous. It was characterized without any doubt as the 2,6-diformyl product. And there is lots of it!
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Magic Muzzlet
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WHy did you take so long? The reaction should be done in one go. I never get lower than 92% of product that performs well in a methylation or
ethylation.
You need to add the 4-methoxyphenol to the methoxide and then don't reflux it but distill off the methanol Azeotrope until the INTERNAL temperature is
95-97C and then begin paraformaldehyde addition. Don't add it too rapidly, the temperature must stay within that range.
The mixture gels at around 85 or so as the phenolate precipitates but keep heating it, don't add the paraformaldehyde until it hits the stated temp...
Takes about 20 mins to reach the correct temp if distilling at a reasonably rapid rate.
If you do it like that you don't need to vac distill but of course it is preferable.
I have heard if you don't hit that 95-97C range and start paraformaldehyde addition you will have lots of unreacted 4-methoxyphenol, but I am puzzled
how you got some diformyl material
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turd
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Doing too many things at the same time! 
| Quote: | The mixture gels at around 85 or so as the phenolate precipitates but keep heating it, don't add the paraformaldehyde until it hits the stated temp...
Takes about 20 mins to reach the correct temp if distilling at a reasonably rapid rate.
If you do it like that you don't need to vac distill but of course it is preferable. |
Well, I knew from the para-ethoxy-phenol that starting addition at 70°C internal temperature works - so why bother. 
| Quote: | | I have heard if you don't hit that 95-97C range and start paraformaldehyde addition you will have lots of unreacted 4-methoxyphenol
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Are you positive that this is also true for para-alkoxyphenols? Or maybe only for unsubstituted phenol? The reaction certainly proceeded well at
70-85°C. It's very unlikely, but maybe there is a paradox effect that more MeOH means a faster reaction due to some solubility effects?
| Quote: | | but I am puzzled how you got some diformyl material |
Must have been the "strong heating" at the end to reach an internal temperature of 95°C. That's what you get for being greedy - a sharp drop in
yield. Next time only with TLC control!
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Magic Muzzlet
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I'm telling you that information from my personal experience having done that formylation on 4-methoxyphenol many times, I've never had it fail and my
yields in consequent steps are normal. How do you know if the reaction "proceeded well" at the lower temperature? You cannot be sure.
I recommend to try it again with the better temp control, I tried addition of paraformaldehyde at the gelling point but the yield lowered to 85% or so
and methylation gave dimethoxybenzene contamination, calling for bisulfite purification. There is always SOME left over starting phenol, but there is
much more if you start addition at the lower temp.
Why bother, because this is a different substrate and performs differently in this formylation, it has been optimized.
You do not need to follow by TLC, take as long as needed for paraformaldehyde addition, then heat for 45mins to an hour and it will be done, but don't
heat it strongly. Remember, 95-97C the whole time. I use a water bath, others have said it doesn't work in the water bath, well it does as I do it all
the time! Maybe add some salt until you get the right temp in the boiling bath.
This also is no problem with water vapor if you are quick, just shield that particular neck...
Good luck
Edit: forgot to say I cover the bath in foil to prevent evaporation issues and such, maybe this accounts for the higher temp, at any rate it is the
best solution for the spot on temperature and you can control it finely by making some vents if it becomes too hot
[Edited on 23-3-2012 by Magic Muzzlet]
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peach
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Ha! I just found the 10 or so grams of it I made last year sitting around in a container of odd bits. I thought I may as well try something with it or
bin it so I could have the flask back. So I ran the Reimer Tiemann formylation with it last week.
-------------------------------------------------------------------------
I made up a solution of 26g NaOH in 32g of water. Whilst it was still hot, I tried rinsing the original flask out into something larger. Which didn't
go well, as it re-solidifies immediately on contact with a cool surface. I upturned the flask and then gently warmed the glass to run it into a 250ml
flask.
I determined the mass change as 9.8g. But I'd call that 9.5 since some of it probably ended up stuck on the walls of the funnel etc.
Warmed it to just over 70C. This is the point at which the contents melt. Began stirring. Not super effective since it tends to form a skin on it's
surface and a crust on the cooler areas of the walls, but it's not too bad. I had wrapped the top hemisphere of the flask with wool. Setup for reflux
and began dripping 13ml of chloroform in over 3h. Establishing a constant drip rate over that length of time is next to impossible, so I'd drip it for
a while, switch it off, back on. The contents quickly go from a soft warm yellow to brown / black. Wondering about the stirring, I occasionally picked
the flask up to give it a swirl by hand. It would foam up, almost to the base of the condenser, as the contents are above the boiling point of the
chloroform.
I continued heating for an hour after the end of the addition, took it off, capped it, ran it under the tap to cool it down and then left it in the
refrigerator overnight. Next morning I gradually acidified it with sulphuric to a pH of 5; the contents are all now in a liquid state, an oily layer
appears atop the aqueous, it's all dark brown / black.
In the Reimer Tiemann example I was using, they steam distilled. I decided to try solvent extraction instead. I noted table salt sized solids within
and thought it best to remove them because they'd only make the separations messier; vacuum filtered, few grams of solid in the cake. Rinsed the flask
out with hot water and poured through.
Retained the filtrate and moved it to a sep funnel. A considerable amount of organic material was sticking to the walls of the filter funnel, the
filter flask and sep funnel.
I decided to try using cyclohexane to wash it all towards the sep funnel (filter cake -> filter flask -> sep funnel). This didn't shift much. I
then shook the resulting hexane with the filtrate and separated. The hexane was a yellow tone.
I set this aside and, suspecting the hexane (having zero polarity) wasn't picking up the material well enough, repeated the process with methylene
chloride. This did a far superior job. It required around 100ml to 150ml to adequately move it all along and the organic phase was now black.
Keeping the two separate, I then removed the solvents and vacuum distilled the results.
From the cyclohexane I retrieved 1.7g of a yellow oil. From the methylene chloride, 3.85g. For a total of 5.6g.
It'd have probably been better ran under some inert gas. No emulsion problems with either solvent. Can be tricky to see the boundary with methylene
chloride without holding it up to a light, due to the intense discolouration of both.
This was not something I was planning to do, and I haven't gotten round to checking precisely what's going on with the results as of yet, but I
thought that may be of some interest to you. I'll see if I can get some TLC scans of it at some point; have been busy drawing graphs for the diethyl
ether thread.
-------------------------------------------------------------------------
Before acidification:
The delightful separation:
The crude yellow oil that results:
[Edited on 24-3-2012 by peach]
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turd
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Quote: Originally posted by Magic Muzzlet  | | I'm telling you that information from my personal experience having done that formylation on 4-methoxyphenol many times, I've never had it fail and my
yields in consequent steps are normal. How do you know if the reaction "proceeded well" at the lower temperature? You cannot be sure.
|
True that. To be sure I would have to do TLCs. But it looked exactly as it should: dissolution of the phenoxide, yellow/orange solution. Clearly the
thing is reacting already at lower temperatures, even if not to completeness.
| Quote: | | You do not need to follow by TLC |
Well, given that our results are so completely contradictory, I think redoing the reaction with TLC control is certainly called for. Now that I have
genuine samples of the un-, mono- and diformylated products, it should be easy to do. But the 50 g aldehyde I got are enough for a long time, so it's
quite down on my list of priorities.
On temperature control: my thermometer is quite long and certainly extended far into the solution (which can become a nuisance in viscous solutions,
because the stir bar tends to smash into the thermometer). Unless I read it wrong - it's absolutely puzzling that I get massive diformylation in 15
min @ 85-95°C, when you get unconverted product with >1h at 95°C. Maybe I added the paraformaldehyde too quickly? What I did note though, was
that when reaching 95°C the solution was getting quite turbid, so maybe it was already getting too concentrated. Maybe I miscalculated/mismeasured
the amount of toluene?
@peach: That's very brave that you try the infamously dirty Reimer-Tiemann, when there's the clean Mg-mediated formylation! I don't think inert
atmosphere will help a lot. IIRC I came across some references of Reimer-Tiemann with the same substrate giving close to quantitative yields. Was this
one of the procedures you followed? And yes, your yellow oil is what my first fraction looks like - don't get it on your fingers - it stains nearly as
badly as HNO3. 
Edit: to/too typo
[Edited on 24-3-2012 by turd]
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peach
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| Quote: Originally posted by turd |
@peach: That's very brave that you try the infamously dirty Reimer-Tiemann, when there's the clean Mg-mediated formylation! I don't think inert
atmosphere will help a lot. IIRC I came across some references of Reimer-Tiemann with the same substrate giving close to quantitative yields.
[Edited on 24-3-2012 by turd] |
It's satisfying to go from such a mess to something approaching clean.
The reference I used yielded around 74%. After acidification they transferred the organic layer to some clean water and steam distilled. I expect some
of the losses occurred just doing that, as it's a rather clingy affair. The same is true of solvent extracting. If I did it again, I think I could
improve on that.
| Quote: | | don't get it on your fingers - it stains nearly as badly as HNO3.
|
Too late, it's already been on whilst cleaning the glass. And you're right.
| Quote: | RIEMER-TIEMANN FORMYLATION OF 4-METHOXYPHENOL (Org. React. Vol 28 p16)
Into a 2000ml three neck flask was placed 125g (1 mol) 4-Methoxyphenol and a still hot solution of 320g (8 mol) NaOH in 400ml H2O (Addition while hot
helps the phenol to dissolve and avoid carbonate formation). The flask was set with a reflux condenser, dropping funnel and thermometer (using a
Claisen adaptor) and mechanical stirrer then heated to ~70°C on the oil bath. When this temperature had been reached, chloroform (160ml, 2 mol) was
added dropwise (and portionwise) over the course of 4 hrs while maintaining the stirring and temperature, over this time the rxn became a very dark
brown with a yellow green froth and a heavy brown precipitate (the sodium phenolate product). The reaction was allowed to stir for a further hour at
the same temperature, allowed to cool and then transfered to a 5000ml flask with the aid of some hot water and subsequently acidified with H2SO4
(150-200ml 10 N). Acidification causes the product to rise to the top as a black oil. The black oil was transferred into a flask with some clean water
and steam distilled (collect ~5000ml distillate). Quite a volume of black tar remains after this distillation. The yellow oil in the distillate was
extracted with DCM and evaporated to yield 112g (74%) 2-hydroxy-5-methoxy-benzaldehyde, can be further purified by vacuum distillation under nitrogen
(bp 133°C/15mmHg).
This material was sufficiently pure for methylation to 2,5-Dimethoxybenzaldehyde and gave a 76% yield with Dimethylsulfate in aqueous NaOH.
Note: The alkali salts of this salicylaldehyde are quite prone to atmospheric oxidation. |
Have you got the reference you mentioned?
[Edited on 24-3-2012 by peach]
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turd
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Oh, I thought they were fairly stable. It's probably enough to degas your solvent(s) and add a bubbler.
I had a look again - it's some Chinese stuff with an amine as base/catalyst. Never mind. BTW: Don't you have a university library nearby? The
chemistry department often provides access to SciFinder/Beilstein/Gmelin...
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Nicodem
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Perhaps this one reference to Huaxue Xuebao posted by Smuv or this other form Huaxue Shiji? However, they are supposed to be para regioselective modifications. Are you sure that a tertiary
amine catalyzed Reimer-Thiemann formylation of p-methoxyphenol was described anywhere?
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turd
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| Quote: Originally posted by Nicodem | | Perhaps this one reference to Huaxue Xuebao posted by Smuv or this other form Huaxue Shiji? [...]. Are you sure that a tertiary amine catalyzed Reimer-Thiemann formylation of p-methoxyphenol was
described anywhere? |
No, no and no.
Could also be an erroneous database entry or me imagining things. Both have happened before. I'll send the reference by U2U, maybe you can do
something with it - I neither have access to the journal, nor can read Chinese!
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DJF90
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| Quote: | | 62 g p-methoxy-phenol |
Thats a questionable scale there sir...
| Quote: | | The solution was added to the Mg(MeO)2 slush with stirring and moisture protection (dark green solution). Additional 100 ml degassed toluene were
added. The reaction was refluxed for 15 min (white/grey precipitate) and the condenser replaced by a distillation bridge. 50 g of ground
paraformaldehyde (directly out of bottle) were added over the course of 1h30, while distilling off a MeOH/toluene azeotrope. At the end of the
addition the internal temperature had risen to 85°C. The reaction was then heated strongly to reach an internal temperature of 95°C in 15
min |
whereas the order of things should be:
| Quote: | | You need to add the 4-methoxyphenol to the methoxide and then don't reflux it but distill off the methanol Azeotrope until the INTERNAL temperature
is 95-97C [b}and then begin paraformaldehyde addition. Don't add it too rapidly, the temperature must stay within that range.
|
| Quote: | | The second fraction was unambiguously identified as the diformylated product! |
And what exactly is unambiguous? If the compound is known and in the literature you can probably get away with 1H, 13C NMR and a melting point. If you
have characterisation data, why don't you share it?
I dont mean to come across as rude or nit-picking, I just want answers. You might also want to work on a smaller scale in future, given the nature of
the compound in question, and the active dose of your target material. One might mistake this example for "commercial production".
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turd
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1) You don't even know what my target is. It's not any of the 2C-X nor any other scheduled substance.
2) Yes - dilettante at work, see introduction - I didn't follow the published procedure. And found something unexpected. I knew that when I was
opening this thread - there is no point in repeating this.
3) I'll share my data with people who a) can use it and b) I trust and c) don't appear condescending. I certainly don't have to prove anything to you.
I couldn't care less whether you believe me or not.
[Edited on 28-3-2012 by turd]
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DJF90
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Based on your intro I was led to believe you were aiming for 2C-B, especially as you make the following statement:
| Quote: | | But the 50 g aldehyde I got are enough for a long time, so it's quite down on my list of priorities. |
I said I didnt mean to come across as rude (or condescending for that matter), I just think if you're after this material for a legitimate use (and
hence scale is not really a factor) then why bother with the babble about drugs to start with. If its not 2C-X then why not share what you're working
on? Why so secretive? I'm sure myself and others would be interested to see stuff done with this material, being how easily made it is. There will be
many people here who are capable of using your data, so why not just put it up. You're saying you've made something, I'm saying prove it. This is how
things are done in the scientific world my friend.
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turd
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Look, I have zero motivation to discuss non-chemistry related things in this thread. If I don't want to post my data to a public message board, then I
will have my reasons. If someone is in the extremely unlikely situation of having use for my data, they can contact me by U2U.
I told you already that I don't care if you think I'm making this up. I also don't care what you think I'm doing and whether that is "legitimate" or
not. So please stop derailing this thread - either post some chemistry or move it to one of the "Non-chemistry" fora.
[Edited on 28-3-2012 by turd]
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DJF90
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I don't think you're making anything up, I just think its bad scientific form that you claim to have made something "unambiguously" yet you don't even
report a melting point of the material, assuming you took one. If you're to say it coincides with a literature value, then who am I to say you're
lying. Its just the fact you present no scientific evidence for your claims. If you have spectral data, then post it, either in the
form of an attachment, image or even a list of peaks. There need not be anything to affiliate you with any of your sources for analytical data.
I couldn't care less if you're making questionable substances. Its not my problem if you wish to ingest them yourself either. I just wish to see good
scientific method. You say it was characterised without doubt. Perhaps you should give others the chance to make their own interpretations of the data
and (hopefully) agree with you.
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Lambda-Eyde
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| Quote: Originally posted by turd | Look, I have zero motivation to discuss non-chemistry related things in this thread. If I don't want to post my data to a public message board, then I
will have my reasons. If someone is in the extremely unlikely situation of having use for my data, they can contact me by U2U.
I told you already that I don't care if you think I'm making this up. I also don't care what you think I'm doing and whether that is "legitimate" or
not. So please stop derailing this thread - either post some chemistry or move it to one of the "Non-chemistry" fora.
|
You are expected to follow scientific discourse on a science forum. Refusing to hand out data such as melting points or spectroscopic data, while
claiming you have "unambiguously" identified the compound (implying you obviously have relevant data that you refuse to share) is quite frankly
not the behavior that I (or any other) expect in scientific communications.
But you probably already know this, you are aware how serious science works, so why are you acting like this? If you actually didn't unambiguously
identify your compound, but rather deduced it from some preliminary results (color, amount of reagent used etc.) then just say so. No reason to act so
stubborn, what we're asking is to tell the whole story (as is expected) and not to become agressive when people ask you politely for something as
trivial as a melting point...
Also, I really don't care if your ultimate target compound is scheduled or not; if it is a psychedelic, stimulant or something related then your scale
of work isn't really acceptable here, whether or not it's actually illegal.
Edit: DJF90 beat me to it (mostly).
[Edited on 28-3-2012 by Lambda-Eyde]
This just in: 95,5 % of the world population lives outside the USA
You should really listen to ABBAPlease drop by our IRC channel: #sciencemadness @ irc.efnet.org
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Nicodem
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Before this curiosity goes too personal, I will say that I checked the product identity evidence that turd so kindly provided me via U2U. I can
witness that what he said about it being "characterized without any doubt as the 2,6-diformyl product" is absolutely true. I can tell you that his
analysis data truly leave absolutely no doubt and would be sufficient to convince even the strictest reviewer. Turd consistently demonstrated his
strictness in regard to the scientific method since he joined the forum. I don't know why he does not share the data publicly, but I trust he has his
own reasons, so we should respect his decision. We should nevertheless be grateful for his contribution to the science of synthesis which will
doubtlessly be useful to several other researchers as well. He could have kept the information for himself and avoid all this unpleasant questioning,
yet he did what any scientist should.
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DJF90
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I appreciate he may not share printouts of data due to the fact that sometimes institutional details are also present and he may not wish us to know
with whom his is affiliated with. However, even a melting point range would be acceptable, yet he declines even this simplest of characterisation
data. How revealing would it be to say his material "melts at xxx*C (lit. value yyy*C)"? I acknowldege that not many of us have access to NMR
facilities as amatuers so every effort should be made to provide strong enough evidence for the constitution of a compound. While he has made this
accessible to yourself, Nicodem, I think that if he's willing to provide experimental details publically then the supporting info should also be
available, especially if he has access to something more rigorous than mp/bp ranges.
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turd
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Nothing special, but someone might find it useful, so I pluck it here:
2,5-Dimethoxybenzaldehyde
To a stirred suspension of 82 g K2CO3 (dried over night at 250°C and ground to a fine powder) and 50 g of the above 2-OH-5-MeO-benzaldehyde in 480 ml
DMF was added 37 ml Me2SO4 in 5 aliquots. After the last addition the internal temperature had risen to 60°C. The reaction was stirred for 16h and
poured into 1.5 l of ice water. The tan precipitate was filtered off and dried in a warm (~30°C) place to obtain 46.3 g of crude
2,5-diMeO-benzaldehyde. The filtrate was diluted to 4 l with water and cooled over night at 6°C, whereby 0.6 g of huge needles of
2,5-diMeO-benzaldehyde formed (see pretty pictures thread). The total nominal yield is 46.9 g (86%), but the product still contained appreciable
amounts of water, which was observed by drops condensing on the walls of the container it was stored in. Furthermore, it is not very pure, giving a
sharp drop in yield in the next step. Therefore the crude 2,5-diMeO-benzaldehyde should be recrystallized.
Ethylenediammonium diacetate
To a stirred solution of 40 g ethylenediamine in 200 ml n-PrOH, 80 g AcOH was added dropwise in such a way to keep the solution from boiling. At the
end of the addition the solution darkened considerably. No precipitate occurred during the addition. The solution was then slowly cooled to room
temperature to obtain needles of ethylenediammonium diacetate. The precipitate was filtered off and washed with MEK until colourless to give 110 g of
slightly off-white product.
2,5-Dimethoxy-beta-nitrostyrene
44 g of 2,5-diMeO-benzaldehyde and 5 g ethylenediammonium diacetate were dissolved in 220 ml IPA by gentle application of heat. Minor impurities did
not dissolve, but were not filtered off (big error!). 20.5 g MeNO2 was added and the solution stirred at RT. The solution progressively darkened and,
probably due to the impurities acting as crystallization nuclei, at the 1h30 point the whole reaction suddenly precipitated. The crude orange
nitrostyrene was filtered off and deemed of inferior quality and therefore recrystallized from EtOAc (cooling must be performed very slowly, because
the nitrostyrene tends to crash out of the solution) to obtain 37 g (67%) of large needles of 2,5-diMeO-beta-nitrostyrene (see pretty pictures
thread).
With the exception of dimethylsulfate all chemicals are available to the amateur.
PS: Thanks to all the people who participated in this thread without whining!
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turd
National Hazard
Posts: 800
Registered: 5-3-2006
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Alright, finally got around to redo the Mg-mediated formylation of p-methoxyphenol. Again, the Mg(OMe)2 was prepared a week in advance which
lead to a brick that took very long to dissolve on addition of paraformaldehyde, but eventually did dissolve completely. This time addition was
started at 85°C, temperature kept at 95°C during addition and for ~30 min after addition. At the end, the reaction became turbid, presumably due to
precipitation Mg-phenoxide.
And indeed, there was only very little high boiling fraction, not enough to bother isolating it. So apparently I really went overboard with additional
heating the first time around. I still have the diformylated product as proof that I am not crazy.
Edit: typo
[Edited on 25-11-2012 by turd]
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chemrox
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Hey Turd,
Could you post the paper here?
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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turd
National Hazard
Posts: 800
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Not sure what you mean...?
I'm just repeating the work of Methyl.Magic (https://www.sciencemadness.org/whisper/viewthread.php?tid=10...) and Klute (https://www.sciencemadness.org/whisper/viewthread.php?tid=10...) in my characteristic dilettante way. The original paper is posted in the first
linked thread.
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lullu
Hazard to Self
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Registered: 2-3-2012
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Did anyone experience that the aldehyde won't solify under 4°C?
Even thin layers on a beaker wall in the fridge won't crystallize, toluene was removed by vacuum destillation and the product has a yellow/orange
color.
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