Sciencemadness Discussion Board

Diethyl ether from chloroethane and sodium ethoxide

Keras - 30-5-2019 at 09:33

Apparently,
C2H5ONa + C2H5Cl → C2H5OC2H5 + NaCl

Has anyone ever attempted this? Sodium ethoxide can apparently be made from ethanol and sodium hydroxide, and chloroethane from ethanol and concentrated hydrochloric acid.

Might be a less risky way than the usual dehydration of ethanol by sulphuric acid at 140 °C.

Pumukli - 30-5-2019 at 11:24

"Has anyone ever attempted this?"

A man called Mr. Williamson probably did. :)

https://en.wikipedia.org/wiki/Williamson_ether_synthesis

Less risky but much more expensive!

Btw. I tried making sodium ethoxide from NaOH and ethanol, I got something, but the condensation reaction I intended to with it failed! It may only mean that I'm inept in practical org. chem. though.

Keras - 30-5-2019 at 12:00

Quote: Originally posted by Pumukli  
"Has anyone ever attempted this?"

A man called Mr. Williamson probably did. :)


I know that :p I meant anyone out here :)

clearly_not_atara - 30-5-2019 at 12:30

Chloroethane is nowhere near as easy to make as you're making it sound. Ethyl bromide is relatively easy with hydrobromic acid.

Keras - 30-5-2019 at 12:41

Quote: Originally posted by clearly_not_atara  
Chloroethane is nowhere near as easy to make as you're making it sound. Ethyl bromide is relatively easy with hydrobromic acid.

I read that chloromethane could be made from ethanol and hydrochloric acid using zinc chloride as a catalyst. In that case, it would be enough to dissolve some zinc into the HCl before adding the ethanol.

What about ethyl iodide?

clearly_not_atara - 30-5-2019 at 13:32

Ethyl iodide works fine. Primary and methyl chloroalkanes are difficult to generate with the Lucas reagent as an extended rxn at high temp is required. Additionally, the low bp of EtCl makes it annoying to distill. Even isopropyl chloride is a technically demanding synth due to low bp.

SWIM - 30-5-2019 at 13:52

Ethyl bromide can also be made with sulfuric acid and sodium or potassium bromide.
This used to be a common lab synth for 1st year organics labs.

Check any old lab manual and you'll probably find a small scale version of that reaction.

The classic acid dehydration of ethanol really isn't bad to do though.
Ice water in condenser and ice cooled receiver in a well ventilated room with an electric heating source does the job with minimal odor.
I have done this in summertime in an apartment building without attracting attention.

Also, it only requires the cheapest of ingredients. H2SO4 drain cleaner and 90-95% ethanol gives good results and you get to save your fine chemicals for other things.

Keras - 31-5-2019 at 00:12

Quote: Originally posted by clearly_not_atara  
Ethyl iodide works fine. Primary and methyl chloroalkanes are difficult to generate with the Lucas reagent as an extended rxn at high temp is required. Additionally, the low bp of EtCl makes it annoying to distill. Even isopropyl chloride is a technically demanding synth due to low bp.


I’m a bit nonplussed here, because I expected precisely the fact that ethyl chloride has a low boiling point to be an advantage, as it would bubble out of the solution of HCl and ethanol and could be condensed in an ice bath cooled flask. However, on the other hand, ethyl iodide has about the same boiling point as ethanol, which would make it a pain to distill out – only liquid chromatography would be suitable at this point.
Quote: Originally posted by SWIM  
Ethyl bromide can also be made with sulfuric acid and sodium or potassium bromide.
This used to be a common lab synth for 1st year organics labs.

Check any old lab manual and you'll probably find a small scale version of that reaction.


Interesting, I will check that out.
Quote: Originally posted by SWIM  
The classic acid dehydration of ethanol really isn't bad to do though. Ice water in condenser and ice cooled receiver in a well ventilated room with an electric heating source does the job with minimal odor. I have done this in summertime in an apartment building without attracting attention.

Also, it only requires the cheapest of ingredients. H2SO4 drain cleaner and 90-95% ethanol gives good results and you get to save your fine chemicals for other things.


I have done it twice, and since I work in an old barn with one wall missing and a roof something like 20 m above ground, I’m not really that worried about lack of ventilation. But I find the main problem to be the high temperature. At 130 °C, a lot of water, alcohol and sulphuric acid passes over through the distillation apparatus, and the end product needs a lot of cleaning. Of course, this is not insuperable, but it’s just annoying to redistill, then neutralise, then dehydrate, etc. And even then, I have a small bottle of thus made diethyl ether, in which I put some KOH flakes to check peroxide formation. I thought it to be reasonably pure, but soon the KOH dissolved and transformed into a yellow glop, probably due to the simultaneous presence of acetaldehyde.

At the end, I simply bought a liter of commercial anhydrous ether for my future Grignard reactions :p – that I will try to recycle as much as possible.

[Edited on 31-5-2019 by Keras]

[Edited on 31-5-2019 by Keras]

Ubya - 31-5-2019 at 07:21

Quote: Originally posted by Keras  
Quote: Originally posted by clearly_not_atara  
Chloroethane is nowhere near as easy to make as you're making it sound. Ethyl bromide is relatively easy with hydrobromic acid.

I read that chloromethane could be made from ethanol and hydrochloric acid using zinc chloride as a catalyst. In that case, it would be enough to dissolve some zinc into the HCl before adding the ethanol.

What about ethyl iodide?


HCl+ZnCl2+alcohol is at the base of the Lucas test to identify tertiary alcohols. This Reaction is very fast for tertiary alcohols because of the carbonation stability, secondary alcohols react but much slower, primary alcohols are inert or need heating and long reaction times. Plus the zinc chloride is equimolar with HCl, "some" is not enough

ErgoloidMesylate - 4-5-2023 at 21:31

Quote: Originally posted by Keras  
Apparently,
C2H5ONa + C2H5Cl → C2H5OC2H5 + NaCl

Has anyone ever attempted this? Sodium ethoxide can apparently be made from ethanol and sodium hydroxide, and chloroethane from ethanol and concentrated hydrochloric acid.

Might be a less risky way than the usual dehydration of ethanol by sulphuric acid at 140 °C.


Sodium ethoxide and ethyl bromide at 55C.
If a solvent is desired, ethanol.

Keras - 4-5-2023 at 23:38

Quote: Originally posted by ErgoloidMesylate  

Sodium ethoxide and ethyl bromide at 55C. If a solvent is desired, ethanol.


Geez, that is an old thread. I have more or less abandoned any idea of producing diethyl ether by Williamson synthesis. Much too wasteful in terms of resources.

Does, however, the acid have to be sulphuric acid? I mean, I understand that using HCl or any halide acid is not possible because it would boil off before the reaction even taking place. But what about phosphoric acid, which, by the way, is not oxidising, so should not produce any tar at the end of the reaction?

clearly_not_atara - 5-5-2023 at 09:31

I don't believe it's necessary to use sulfuric acid. The mechanism certainly doesn't suggest it is. One advantage of sulfuric acid is that it's a strong hydrogen bond donor and acceptor, so it reduces the tendency of ethanol to boil away.

Phosphoric acid may or may not be strong enough. pKa EtOH2+ ≈ -2.5 IIRC.

Toluenesulfonic acid is liquid at the relevant reaction temperature range. The formation of ethylene might also be a mechanism of tar formation. But TsOH can be easier to handle for other reasons.

ErgoloidMesylate - 5-5-2023 at 11:10

Quote: Originally posted by Keras  
Quote: Originally posted by ErgoloidMesylate  

Sodium ethoxide and ethyl bromide at 55C. If a solvent is desired, ethanol.


Geez, that is an old thread. I have more or less abandoned any idea of producing diethyl ether by Williamson synthesis.


Don't take this personally, but this forum can be searched by anyone. It is for that info be readily available I typed it. I never believed or thought you wanted to synth ether, as i have zero reason to think so.