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Author: Subject: Acetaldehyde synthesis
clearly_not_atara
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[*] posted on 16-9-2020 at 06:21


In reality producing acetaldehyde isn't all that hard. What is hard is producing acetaldehyde in significant quantities and in such a way that it can be separated from the reaction mixture, condensed, and isolated.

It's difficult, for example, to condense a compound with bp 20 C when that compound is co-produced in the efflux stream with much larger quantities of water, bp 100 C, and when said gas stream emerges at nearly 200 C.

It is likewise not very easy to isolate acetaldehyde from aqueous rxn mixtures since its bisulfite adduct is not as insoluble as those of larger aldehydes, and it may polymerize under the alkaline conditions typically used for bisulfite adduct deprotection. Bisulfite adducts may also be deprotected with acid, but this produces copious SO2.

As such, the great majority of syntheses posted in this thread are not really solving the right problem. IMHO, if you want a practical synth of acetaldehyde, what you're really after is an oxidation of ethanol that produces 1,1-diethoxyethane -- acetaldehyde diethyl acetal -- in situ. This compound can easily be separated from the reaction mixture and pure acetaldehyde obtained by acidic cleavage under relatively mild conditions with few co-products. It is stable and can be stored.

To that end, I offer the direct photocatalytic oxidation of ethanol to 1,1-diethoxyethane over two catalysts: 1% Pt-doped TiO2 nanorods and Cd-Ni-Mo sulfide.

https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10...

https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10....

While the photocatalysts take a little work -- hardly impractical IMO -- they offer the possibility of one-step large-scale production of DEE qua acetaldehyde in a form that is stable and easy to isolate and store.

But be aware that while acetals such as DEE usually do not form peroxides, the risk must not be ignored.

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[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 5-11-2020 at 17:53


I see this threads been dead for a while :P, but this paper outlines a way of oxidizing alcohols using O2 over some Pd/C like catalysts. https://pubs.acs.org/doi/pdf/10.1021/cr0200116

[Edited on 6-11-2020 by Triflic Acid]
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[*] posted on 24-11-2020 at 13:54


Quote: Originally posted by Corrosive Joeseph  
Quote: Originally posted by S.C. Wack  
Page 4686 of JCS (1956) claims a 50% yield by reflux of EtOH with excess MnO2 for 20 min. No explicit experimental is given in this case. A number of aldehydes and a few ketones are prepared, but my copy (from microfilm) is of poor quality.


Barakat et al. - Oxidation of Organic Compounds by Solid Manganese Dioxide - Notes, Journal of the Chemical Society (1956) Pages 4685-4687


CJ


Did anyone try this method yet? It seems like the most convinient method...
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EverythingAl2O3
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[*] posted on 2-12-2020 at 12:43


It might just be easier to attempt to partially dehydrate ethylene glycol. An enol will form and tautomerize. It could be done pretty easily with say H2SO4, H3PO4 or Al2O3. Though if there if there is a reason why it wouldn't work someone let me know.
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[*] posted on 14-4-2021 at 10:33


Quote: Originally posted by EverythingAl2O3  
It might just be easier to attempt to partially dehydrate ethylene glycol. An enol will form and tautomerize. It could be done pretty easily with say H2SO4, H3PO4 or Al2O3. Though if there if there is a reason why it wouldn't work someone let me know.

Forgive me for not reading this thread, but what about NurdRage's YouTube videos for producing sodium? He purifies sodium by boiling it in dioxane, which he produces from ethylene glycol and sulfuric acid. And the side product in that production is the ethylene glycol acetal of acetaldehyde. He vents a ton of acetaldehyde saying to get rid of that nasty carcinogen. Opportunity abounds. I plan to use this myself as a way to produce dioxane plus the acetaldehyde I require.
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draculic acid69
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[*] posted on 14-4-2021 at 17:41


Quote: Originally posted by Jenks  
Quote: Originally posted by EverythingAl2O3  
It might just be easier to attempt to partially dehydrate ethylene glycol. An enol will form and tautomerize. It could be done pretty easily with say H2SO4, H3PO4 or Al2O3. Though if there if there is a reason why it wouldn't work someone let me know.

Forgive me for not reading this thread, but what about NurdRage's YouTube videos for producing sodium? He purifies sodium by boiling it in dioxane, which he produces from ethylene glycol and sulfuric acid. And the side product in that production is the ethylene glycol acetal of acetaldehyde. He vents a ton of acetaldehyde saying to get rid of that nasty carcinogen. Opportunity abounds. I plan to use this myself as a way to produce dioxane plus the acetaldehyde I require.


Many ppl have done this rxn for the dioxane but no one yet has done this for the purpose of capturing and measuring the yeild of the acetaldehyde. If U do this
please report back with yeild.it would contribute to this thread greatly
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EverythingAl2O3
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[*] posted on 28-4-2021 at 16:56


Have we also considered the Corey-Kim oxidation? N-chlorosuccinimide with a unhindered thioether and a tertiary amine/hindered amine like triacetoneamine. Yes DMS would be pretty smelly, but if one can make a long chain sulfide (Wikipedia says dodecyl methyl sulfide was used as a less noxious sulfide) it wouldn't be as much of an issue. NCS can be regenerated by reacting Succinimide with bleach. Only downside is cooling to around -40 to -25C and 10h ish reaction time. But the reagents can be regenerated with cheap chemicals.
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[*] posted on 5-6-2021 at 19:32


Quote: Originally posted by EverythingAl2O3  
Have we also considered the Corey-Kim oxidation? N-chlorosuccinimide with a unhindered thioether and a tertiary amine/hindered amine like triacetoneamine. Yes DMS would be pretty smelly, but if one can make a long chain sulfide (Wikipedia says dodecyl methyl sulfide was used as a less noxious sulfide) it wouldn't be as much of an issue. NCS can be regenerated by reacting Succinimide with bleach. Only downside is cooling to around -40 to -25C and 10h ish reaction time. But the reagents can be regenerated with cheap chemicals.


That seems a little much for acetaldehyde, don’t you think? If you want a cheap and easy way of getting acetaldehyde as a reagent, metaldehyde - acetaldehyde tetramer - is available in bulk from Chinese sellers. It is the active ingredient in slug killer

EDIT: it is also available in the US in slut bait, but only at 3-5% and it is not the best to work with. It can be sublimed but the slug bait, at least the kind I used, was a black goo that smelled a special kind of rank, especially when heated. Also, while sublimation is an effective way of separating the crystalline material it is a very very very VERY long and tedious process and I gave up after only a few grams (took me all day a while back)

[Edited on 6-6-2021 by Opylation]
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[*] posted on 6-6-2021 at 07:19


Yes it is a bit much for it. Though it seems far more regenerable than using Chromate oxidizers mentioned before in the thread. I think using hypochorite in glacial acetic acid might work better than anything else, but need to actually test to make sure it doesn't over oxidize.
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[*] posted on 12-9-2021 at 02:43


Did anyone think about dry distillation of a mixture of calcium acetate with a huge excess of calcium formate? It should produce a lot of formaldehyde which just escapes, and quite a bit of acetaldehyde with some acetone that can be collected. Then you just need to separate the acetone either by distilling out the acetaldehyde or adding a bit of acid to turn it into paraldehyde and distill off the acetone.

Unless someone knows that it doesn't work, I'll have to give this a try, I just need to buy some formic acid.

EDIT: Okay, I decided to finally try it instead of just theorizing, I got really good yields for a high boiling ketone that way, so this seems promising to me, I'll report back when I'm done.

[Edited on 12-9-2021 by theAngryLittleBunny]
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[*] posted on 10-12-2021 at 10:27
Reagents?


I came across a few experiments I want to try and need acetaldehyde.
I drew out a few mechanisms which would bring me there, which seem a bit different from the routes used here. Perhaps its because the reagents are not so easy to get.

1. Swern oxidation of ethanol (DMP or PCC could be used, also Chromic acid via various dichromates and chromates)
2. keto-enol tautomerization of acetalyne using NaBH3, THF & H2O2, NaOH
3. Convert acetonitrile to acetaldehyde with DiBAL-H

Has anyone tried any of these methods? They are all very simple, textbook examples it seems. Are any of these reagents accessible without "borrowing" from your lab?
I'm pretty new to at-home chemistry, and the labs I've been in for university just have everything on hand. Can one just order reagents such as PCC through major suppliers like Sigma?

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[*] posted on 10-12-2021 at 11:14


Quote: Originally posted by tetrogen  
Are any of these reagents accessible without "borrowing" from your lab?
I'm pretty new to at-home chemistry, and the labs I've been in for university just have everything on hand. Can one just order reagents such as PCC through major suppliers like Sigma?


One can usually not order reagents directly from Sigma/Alfa/etc. The exception is if you have a bona fide lab or commercial address that you can use, and it may be difficult even then.

Many reagents can be found/extracted/produced from "over the counter" materials. PCC for example is certainly accessible to the amateur.

Also, there are individuals and companies that will act as middlemen between you and these suppliers, for a fee. Some individuals advertise these services on the Reagents and Apparatus Acquisition forum. Chemsavers is good for the more exotic chemicals. DMP is available through them...

... as well as acetaldehyde itself :D But where's the fun in that?




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[*] posted on 10-12-2021 at 20:22


Thanks for the info. I've been having fun with extracting reagents and elements from OTC products as opposed to just purchasing everything as-is, so I don't mind that.

I wasn't aware that PCC was one I could find in an OTC product, so I'll have to look into that more. That would probably be the simplest route if it works, too.
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[*] posted on 10-12-2021 at 21:51


You can't get PCC OTC, but you can produce it from pottery-grade Cr2O3 and niacin, as well as a load of other reagents. Welcome to the forum.



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[*] posted on 11-12-2021 at 00:35


Why not the MnO2 , H2SO4 methode? MnO2 is easier to get the chrome compounds.
Pharmacy book says: 4 parts EtOH 80%, 6 parts MnO2 and 6 parts H2SO4 with 4 parts H2O are destilled.
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[*] posted on 17-12-2021 at 13:29


Thanks. I saw the Doug's Lab video on it shortly after. If I do make it, I'll likely go that route, although he used CrO3 which is quite a bit harder to get than Cr2O3, so the latter option would be ideal.
The other method is certainly one I'll keep in mind, although the Cr methods will give me a reason to also produce pyridine, which will leave me with two useful reagents when I'm done. I will certainly post my notes if I do it.
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[*] posted on 17-12-2021 at 14:34


I swear I just looked through the complete thread, I was remembering a certain method which did not include an oxidation?
Something via SN2 first from EtI and then... I don't remember?

I could swear I posted it in here?

Wanted to try this, still would, but what the hell was it even?
Do we have a second acetaldehyde thread?

If so, sorry....




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[*] posted on 25-12-2021 at 11:40


karlos³
leading ethanol vapor over hot Cu metal?
depolymerization of metaldehyde (antislug compound)?
hydratation of acetylene over Hg2+ salt catalyst?




If there is a heaven, it seems not to be materially based. Does chemistry exist there and if yes, how does it look like? Are there good souls well supplied with laboratory equipment, glass, chemicals and information?
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