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clearly_not_atara
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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.
Attachment: zhang2015.pdf (849kB)
This file has been downloaded 718 times
Attachment: chao2018.pdf (3.4MB)
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Triflic Acid
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I see this threads been dead for a while  , 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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NaK
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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.
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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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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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Jenks
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| 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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| 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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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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Opylation
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| 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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EverythingAl2O3
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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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theAngryLittleBunny
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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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tetrogen
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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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timescale
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| 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?
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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  But where's the fun in that?
Est-il une beauté aussi belle que le rêve ?
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tetrogen
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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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Triflic Acid
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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.
There wasn't a fire, we just had an uncontrolled rapid oxidation event at the power plant.
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Alkoholvergiftung
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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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tetrogen
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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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karlos³
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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....
verrückt und wissenschaftlich
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Fery
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karlos³
leading ethanol vapor over hot Cu metal?
depolymerization of metaldehyde (antislug compound)?
hydratation of acetylene over Hg2+ salt catalyst?
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Parakeet
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I recently synthesized acetaldehyde by the oxidation of ethanol using acidified potassium dichromate solution. Ethanol, potassium dichromate and
sulfuric acid was mixed in a test tube and heated by a water bath. I attached a rubber tube to the test tube in order to lead and dissolve the
aldehyde in few mL of chilled water.
It went pretty well. It had a characteristic smell of acetaldehyde. It also showed a positive result to the Fehling’s solution.
However, as the reaction proceeded, the solution which have dissolved the aldehyde became cloudy. Acetaldehyde should be miscible with water. I have
no idea what this cloudy thing is. Does anyone have any idea?
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SyntheticFunk
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| Quote: Originally posted by Parakeet | I recently synthesized acetaldehyde by the oxidation of ethanol using acidified potassium dichromate solution. Ethanol, potassium dichromate and
sulfuric acid was mixed in a test tube and heated by a water bath. I attached a rubber tube to the test tube in order to lead and dissolve the
aldehyde in few mL of chilled water.
It went pretty well. It had a characteristic smell of acetaldehyde. It also showed a positive result to the Fehling’s solution.
However, as the reaction proceeded, the solution which have dissolved the aldehyde became cloudy. Acetaldehyde should be miscible with water. I have
no idea what this cloudy thing is. Does anyone have any idea? |
It's likely the self condensation product. Acetaldehyde has an enolizable alpha proton and is also a relatively good electrophile at the carbonyl
carbon. It readily reacts with itself to for the aldol condensation product.
Alternatively acetaldehyde can trimerize through a different mechanism where the oxygens act as the nucleophile. Fortunately this trimerization is
reversible in addition to being relatively stable in storage conditions.
I store my acetaldehyde as the ammonia trimer (google acetaldehyde ammonia trimer). You can get this by collecting the acetaldehyde distillate from
your reaction in some organic solvent while bubbling anhydrous ammonia into it.
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Parakeet
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Thank you for the information. That explains it.
I don’t intend to use the acetaldehyde for other experiments. I just wanted to explore the science.
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clearly_not_atara
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Since I posted this, some authors developed a much more OTC method for the same conversion:
https://pubs.acs.org/doi/abs/10.1021/jacs.1c05976
Unfortunately, it is not available from the Kazakh communist filesharing server. But the Supporting Information shows that the electrolyte is Bu4NCl,
which is a little easier to obtain than Ni-doped MoS2 or platinum.
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Benignium
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clearly_not_atara - It seems like there is another way. I went to the List of preprint repositories page on Wikipedia, tried
a few of the larger multidisciplinary resources. Scienceopen produced a result for the DOI, and clicking Further versions led to U.S. Department of Energy Office of Scientific and Technical Information where the Accepted Manuscript (DOE) can be downloaded.
Thank you for the article! You do keep rolling out the hits. 
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leucine75
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I believe one of the major by products of producing 1,4 dioxane is acetaldehyde just use nurd rages method using anti freez and sulfuric acids yields
some impure acetaldehyde on the second disatiion
Leucine75,
sorry about the Grammer
[Edited on 21-9-2023 by leucine75]
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EF2000
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For ones who, like me, can't open osti.gov:
Attachment: siqi-li-selective-chloride-mediated-neat-ethanol.pdf (866kB)
This file has been downloaded 228 times
Wroom wroom
"The practice of pouring yourself alcohol from a rocket fuel tank is to be strongly condemned encouraged"
-R-1 User's Guide
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