Sciencemadness Discussion Board

Oxidation of ethanol by hypochlorite

xfusion44 - 6-8-2014 at 08:46

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]

Zyklon-A - 6-8-2014 at 10:28

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.
Quote:

With this method is kinda tricky to collect ethanal

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]

xfusion44 - 6-8-2014 at 10:48

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.

xfusion44 - 6-8-2014 at 10:54

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.

BlackDragon2712 - 6-8-2014 at 16:19

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.

xfusion44 - 6-8-2014 at 16:57

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.

WGTR - 6-8-2014 at 17:31

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.

xfusion44 - 6-8-2014 at 18:51

Quote: Originally posted by WGTR  
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.


Thanks, I'll check it :D

PHILOU Zrealone - 7-8-2014 at 13:30

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]

Eddygp - 9-8-2014 at 02:52

I found this, which seems pretty straightforward (if you have the reagents):
http://www.creative-chemistry.org.uk/alevel/module3/document...

xfusion44 - 9-8-2014 at 06:24

Quote: Originally posted by Eddygp  
I found this, which seems pretty straightforward (if you have the reagents):
http://www.creative-chemistry.org.uk/alevel/module3/document...


No, I unfortunately do not have sodium dichromate :( And It's expensive on ebay. But thanks.

xfusion44 - 9-8-2014 at 06:28

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...

PHILOU Zrealone - 9-8-2014 at 12:20

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 ;)

xfusion44 - 10-8-2014 at 09:14

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 :)

mnick12 - 10-8-2014 at 10:58

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.

FireLion3 - 12-8-2014 at 08:58

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)


Nicodem - 12-8-2014 at 11:13

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.

FireLion3 - 12-8-2014 at 14:10

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)



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]

Nicodem - 13-8-2014 at 07:43

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 ...

PHILOU Zrealone - 20-8-2014 at 03:46

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