Synthesizing Ethylene: C2H6O2 + 2Na → 2(CH2)

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SUMMARY

The synthesis of ethylene (C2H4) from ethylene glycol (C2H6O2) using sodium (Na) is discussed, highlighting the potential dangers and misconceptions surrounding the reaction. The proposed reaction, C2H6O2 + 2Na → 2(CH2) + 2(NaOH), is incorrect as it does not yield the expected products. Instead, the reaction with sodium produces hydrogen gas and potentially alkoxides, with thermal decomposition of sodium ethoxide yielding ethylene under specific conditions. Proper laboratory procedures and professional oversight are essential for safe experimentation.

PREREQUISITES
  • Understanding of organic chemistry principles, particularly alcohol reactivity.
  • Familiarity with laboratory safety protocols when handling reactive metals like sodium.
  • Knowledge of thermal decomposition reactions and their products.
  • Access to synthesis handbooks, such as Vogel's Textbook of Practical Organic Chemistry.
NEXT STEPS
  • Research the thermal decomposition of sodium ethoxide and its products.
  • Learn about safe laboratory practices for handling sodium and other reactive metals.
  • Explore alternative methods for synthesizing ethylene, including dehydration of alcohols.
  • Review synthesis procedures in organic chemistry textbooks for accurate methodologies.
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Chemistry students, amateur chemists, and anyone interested in organic synthesis and safe laboratory practices will benefit from this discussion.

Praestrigiator
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I'm trying to get a hold of Ethylene, but because of it's properties it's not sold commercially, so I'm trying to find a way to synthesize it.
The closest thing I can find to synthesize it is Ethylene glycol
I'm pretty sure I could add Na as so
C2H6O2 + 2Na → 2(CH2) + 2(NaOH)
The problem is then how to remove the sodium hydroxide from solution without further reactions effecting the Ethylene.
 
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Praestrigiator said:
because of it's properties it's not sold commercially

Yes it is.

Praestrigiator said:
I'm pretty sure I could add Na

You can add Na, but you won't get the product you expect.

There are known laboratory procedures for preparing ethene, any decent synthesis handbook (like Vogel's Textbook of Practical Organic Chemistry) will have them.
 
Borek said:
Yes it is.
I couldn't find a place to buy it.
Borek said:
You can add Na, but you won't get the product you expect.
What will I get then? Is there some other part of ethylene glycol that would react with the Na sooner than the hydroxyl group?
 
Praestrigiator said:
I am not old enough to purchase Ethanol legally

So where are you going to get metallic sodium from? Is it sold to everyone?

To be honest (and blunt): if you have no idea what are possible reactions between an alcohol and metallic sodium, you should not even try what you are planning. It is simply way too dangerous.
 
Praestrigiator said:
I am not old enough to purchase Ethanol legally
You might be able to purchase denatured ethanol at a hardware store. I don't know the exact rules. But you do need to be careful and get some supervision from people who have more experience than you do. If you still want to pursue this, at least have a look at this page: http://mattson.creighton.edu/AllGases.html Ethylene is included on the list of gases and the site gives a (relatively) easy procedure for its synthesis (along with a few interesting experiments).
 
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Borek said:
So where are you going to get metallic sodium from? Is it sold to everyone?
Metallic sodium is fairly easy to acquire

Borek said:
To be honest (and blunt): if you have no idea what are possible reactions between an alcohol and metallic sodium, you should not even try what you are planning. It is simply way too dangerous.
I've done plenty of chemistry before, I'm adept at certain aspects of it, I know lab protocol, the reason I am asking is because you made a fairly declarative statement that the reaction would not go as I had planned.
 
TeethWhitener said:
You might be able to purchase denatured ethanol at a hardware store. I don't know the exact rules. But you do need to be careful and get some supervision from people who have more experience than you do. If you still want to pursue this, at least have a look at this page: http://mattson.creighton.edu/AllGases.html Ethylene is included on the list of gases and the site gives a (relatively) easy procedure for its synthesis (along with a few interesting experiments).
Yeah, maybe I should take this to school and get help from my former Chem teacher to do this, I'm fairly certain I could do it, but since you're both warning me I should probably do this with a professional.
 
  • #10
Hint: -OH group in alcohols is slightly acidic. Adding sodium to any alcohol will produce a gas, but not the one you expect.
 
  • #11
Borek said:
Hint: -OH group in alcohols is slightly acidic. Adding sodium to any alcohol will produce a gas, but not the one you expect.
I can't believe I missed something that should've been so obvious
C2H6O2 + 4(Na) → C2H4 + 2(Na2O) + H2
Perhaps I should do this only with professional oversight, because I very well could've exploded if I had done this reaction as I had planned.
 
  • #12
Praestrigiator said:
C2H6O2 + 4(Na) → C2H4 + 2(Na2O) + H2

That's still wrong - you have correctly identified hydrogen as a product, but you won't get neither Na2O nor ethylene. I would expect some alkoxide.
 
  • #13
Borek said:
That's still wrong - you have correctly identified hydrogen as a product, but you won't get neither Na2O nor ethylene. I would expect some alkoxide.
I won't exclude the possibility that the alkoxide decomposes into ethylene and Na2O on heating.

Edit: Just looked it up: page 598 of

https://books.google.de/books?id=bD...Sodium ethoxide thermal decomposition&f=false

states that main products of thermal decomposition at temperatures above 573K of the ethoxide are methane and ethylene besides some ethane, propylene and others.
 
Last edited:
  • #14
Thanks for the correction. Actually I didn't though about a further thermal decomposition.

But my main line of thinking was that I don't expect the reaction to run "clean", I would expect a mixture of products (even more complicated than the one produced on the ethoxide decomposition, presence of the second -OH seems to be giving additional pathways).
 

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