xfusion44
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Oxidation of ethanol by hypochlorite
Hi!
I'm new to this forum, and I would like to make acetaldehyde (ethanal), but I don't know how to do that otherwise than with pyrolisis of ethanol
(ethanol vapors are converted into ethanal with red hot copper catalyst). With this method is kinda tricky to collect ethanal, since it has boiling
point around 21°C and it requires oxygen, so it cant be done in closed containers. I found out that it can be done with sodium hypochlorite, but it
requires a special catalyst to do that. I saw one on youtube that did this, using calcium hypochlorite and it didn't seemed that he used any catalyst,
he was just heating the solution... So, is it possible to make ethanal, using ethanol and calcium hypochlorite? Or if it's possible, I would rather
use sodium hypochlorite. I will add ethanal to my chemicals collection and use it for some further experiments 
Thanks for your help
Best regards, xfusion44
PS: here is the video that i saw, about making ethanal with CaClO2: https://www.youtube.com/watch?v=Bx584hCfWHQ
So, would that work just like that? Mixing reactants and heating them?
And I found this on wikipedia: "In the presence of a phase-transfer catalyst, alcohols are oxidized to the corresponding carbonyl compound." on the
site of sodium hypochlorite (scroll down to "reactions"). http://en.wikipedia.org/wiki/Sodium_hypochlorite
[Edited on 6-8-2014 by xfusion44]
[Edited on 6-8-2014 by xfusion44]
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Zyklon-A
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Do you have a reference to where it said it requires a catalyst?
Here is a site that shows the yields of the oxidation of differant alcohols using either NaClO or Ca(ClO)2.
And Here's a PDF : Sodium Hypochlorite Oxidation of Alcohols.
I can't seem to find anything about ethanol specifically, which probably suggests it doesn't work well or at all.
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With this method is kinda tricky to collect ethanal
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You are going to have to distill it, which (needless to say) is going to be quite hard. Perhaps use ethanol and dry ice to cool the condenser.
[Edited on 6-8-2014 by Zyklon-A]
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xfusion44
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| Quote: | | Do you have a reference to where it said it requires a catalyst? |
Here: In the presence of a phase-transfer catalyst, alcohols are oxidized to the corresponding carbonyl compound.
I found that here: http://en.wikipedia.org/wiki/Sodium_hypochlorite
Yeah, I thought about distilling, but the problem is, that there must be oxygen presence and if I connect condenser on the flask, it would stop the
reaction almost immediately 
And thanks for the links, I'll check them.
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xfusion44
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| Quote: | | I can't seem to find anything about ethanol specifically, which probably suggests it doesn't work well or at all. |
Probably, because on the first link they tested reactions with secondary alcohols, but ethanol is primary alcohol.
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BlackDragon2712
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what about decomposition of metaldehyde? it is used as a pesticide against snails.
wikipedia says "... upon heating to about 80 °C, metaldehyde reverts to acetaldehyde." though acetaldehyde has a boiling point of 20°C approx. it
should be done with a very good and large condenser...
I couldn't find any reference on this but it sure deserves a go.
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xfusion44
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Quote: Originally posted by BlackDragon2712  | what about decomposition of metaldehyde? it is used as a pesticide against snails.
wikipedia says "... upon heating to about 80 °C, metaldehyde reverts to acetaldehyde." though acetaldehyde has a boiling point of 20°C approx. it
should be done with a very good and large condenser...
I couldn't find any reference on this but it sure deserves a go. |
Not bad idea, but on ebay there are very high prices just for single bottle of tablets with 3% metaldehyde :-/ Maybe I should check some stores if
they have this.
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WGTR
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You might want to direct your attentions to this thread:
https://www.sciencemadness.org/whisper/viewthread.php?tid=55
It's the official acetaldehyde thread. At some point during it's 13 pages,
I think it addresses ethanol oxidation with hypochlorites.
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xfusion44
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Thanks, I'll check it 
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PHILOU Zrealone
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The dangerously explosive ethyl hypochlorite ester does decompose into ethanal and HCl...
CH3-CH2-OH + NaOCl + HO2C-CH3 --> CH3-CH2-OCl + NaO2C-CH3 + H2O
CH3-CH2-OCl --> CH3-CH=O + HCl
So if isolate the ester and you dilute it into an inert solvent with suspended CaCO3...eventually upon heating you would get ethanal.
The CaCO3 will neutralise the gaseous HCl...
CaCO3 + 2HCl --> CaCl2 + H2O + CO2
In the case your solvent is anhydrous; the traces of water formed will help catching the HCl and will allow a better reaction with the dry CaCO3.
[Edited on 8-8-2014 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Eddygp
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I found this, which seems pretty straightforward (if you have the reagents):
http://www.creative-chemistry.org.uk/alevel/module3/document...
there may be bugs in gfind
[ˌɛdidʒiˈpiː] IPA pronunciation for my Username |
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xfusion44
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No, I unfortunately do not have sodium dichromate And It's expensive on ebay. But
thanks.
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xfusion44
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| Quote: Originally posted by PHILOU Zrealone | The dangerously explosive ethyl hypochlorite ester does decompose into ethanal and HCl...
CH3-CH2-OH + NaOCl + HO2C-CH3 --> CH3-CH2-OCl + NaO2C-CH3 + H2O
CH3-CH2-OCl --> CH3-CH=O + HCl
So if isolate the ester and you dilute it into an inert solvent with suspended CaCO3...eventually upon heating you would get ethanal.
The CaCO3 will neutralise the gaseous HCl...
CaCO3 + 2HCl --> CaCl2 + H2O + CO2
In the case your solvent is anhydrous; the traces of water formed will help catching the HCl and will allow a better reaction with the dry CaCO3.
[Edited on 8-8-2014 by PHILOU Zrealone] |
Intrusting reaction, but where to find that ethyl hypochlorite? All of the reactions for producing ethanal are so complicated, either I dont have one
of the reagents or proper equipment...
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PHILOU Zrealone
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| Quote: Originally posted by xfusion44 | | Quote: Originally posted by PHILOU Zrealone | The dangerously explosive ethyl hypochlorite ester does decompose into ethanal and HCl...
CH3-CH2-OH + NaOCl + HO2C-CH3 --> CH3-CH2-OCl + NaO2C-CH3 + H2O
CH3-CH2-OCl --> CH3-CH=O + HCl
So if isolate the ester and you dilute it into an inert solvent with suspended CaCO3...eventually upon heating you would get ethanal.
The CaCO3 will neutralise the gaseous HCl...
CaCO3 + 2HCl --> CaCl2 + H2O + CO2
In the case your solvent is anhydrous; the traces of water formed will help catching the HCl and will allow a better reaction with the dry CaCO3.
[Edited on 8-8-2014 by PHILOU Zrealone] |
Intrusting reaction, but where to find that ethyl hypochlorite? All of the reactions for producing ethanal are so complicated, either I dont have one
of the reagents or proper equipment... |
If you do a search in subforum dedicated to explosives with keyword "ethyl hypochlorite" you will certainly find it 
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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xfusion44
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| Quote: Originally posted by PHILOU Zrealone | | Quote: Originally posted by xfusion44 | | Quote: Originally posted by PHILOU Zrealone | The dangerously explosive ethyl hypochlorite ester does decompose into ethanal and HCl...
CH3-CH2-OH + NaOCl + HO2C-CH3 --> CH3-CH2-OCl + NaO2C-CH3 + H2O
CH3-CH2-OCl --> CH3-CH=O + HCl
So if isolate the ester and you dilute it into an inert solvent with suspended CaCO3...eventually upon heating you would get ethanal.
The CaCO3 will neutralise the gaseous HCl...
CaCO3 + 2HCl --> CaCl2 + H2O + CO2
In the case your solvent is anhydrous; the traces of water formed will help catching the HCl and will allow a better reaction with the dry CaCO3.
[Edited on 8-8-2014 by PHILOU Zrealone] |
Intrusting reaction, but where to find that ethyl hypochlorite? All of the reactions for producing ethanal are so complicated, either I dont have one
of the reagents or proper equipment... |
If you do a search in subforum dedicated to explosives with keyword "ethyl hypochlorite" you will certainly find it |
Ok, thanks
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mnick12
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If you are going to synthesize ketones or aldehydes from alcohols from bleach you will need and acid catalyst to generate the active oxidant. Back in
Ochem we used acetic acid, which is a good choice.
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FireLion3
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If you attempt to oxidize Ethanol with a hypochlorite it will form an ether and not acetaldehyde. This is because the electrophilic intermediate
reacts with another alcohol in solution. Hypochlorites can oxidize secondary alcohols to carbonyls but the only primary alcohol it works on is benzyl
alcohol.
C.Y. Meyers, J. Org. Chem. , 26, 1046 (1961)
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Nicodem
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| Quote: Originally posted by FireLion3 | | If you attempt to oxidize Ethanol with a hypochlorite it will form an ether and not acetaldehyde. This is because the electrophilic intermediate
reacts with another alcohol in solution. |
What? Please provide a reference for that claim.
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FireLion3
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| Quote: Originally posted by Nicodem | | Quote: Originally posted by FireLion3 | | If you attempt to oxidize Ethanol with a hypochlorite it will form an ether and not acetaldehyde. This is because the electrophilic intermediate
reacts with another alcohol in solution. |
What? Please provide a reference for that claim. |
There was an initial typo in my post, as esters was meant, not ethers.
Nicodem did you not see the reference in my initial post? You seem to have excluded it from your quote of mine.
Here is the PDF (attached) relating directly to the oxidation of alcohols with hypochlorite's.
Attachment: thf2gbl.ca-hypo.pdf (563kB)
This file has been downloaded 674 times
| Quote: |
Oxidation of primary alcohols under identical conditions gave an aldehyde only in the case of benzyl alcohol (11). Other primary alcohols gave esters
as in Table 2. This table also includes our results on the oxidation of ethers to esters. Though the yields were not nearly as good for the alcohols,
the data is reported because of the unusual and potentially useful transformation12. The ethers were oxidized under similar conditions as the alcohols
except that the reactions were carried out at RT for 4-16 hours. Heating does not seem to increase yield.
...
11 - C.Y. Meyers, J. Org. Chem. , 26, 1046 (1961)
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If OP had googled the question he is asking before asking it, he would see this exact paper come up (on Erowid) within the first 5 results, along with
several other paper. There are several links on that first page that mention primary (non benzyl) alcohols are oxidized to esters.
[Edited on 12-8-2014 by FireLion3]
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Nicodem
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| Quote: Originally posted by FireLion3 | There was an initial typo in my post, as esters was meant, not ethers.
Nicodem did you not see the reference in my initial post? You seem to have excluded it from your quote of mine. |
Yes, I excluded all that was not relevant to the claimed condensation to ethers. I checked the article and there was nothing about it, but since you
meant esters ...
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PHILOU Zrealone
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There is a side reaction between the hypochlorous ester of primary alcohols and the formed aldehyde...
CH3-CH2-OCl --> CH3-CH=O + HCl
CH3-CH2-OCl + CH3-CH=O --> CH3-C(=O)-O-CH2-CH3 + HCl
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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