macckone
Dispenser of practical lab wisdom
Posts: 2168
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline
Mood: Electrical
|
|
1,2 dichloroethane synthesis
I am looking for a good OTC synthesis of 1,2 dichloroethane.
My first thought was to do a replacement reaction with zinc chloride and HCl similar to isopropyl and ethyl chloride using ethylene glycol.
The end product has an azeotrope with water even though it is not very soluble.
This looks like a good solvent. And has other uses such as Williamson ether synthesis.
|
|
|
RustyShackleford
Hazard to Others
Posts: 200
Registered: 10-12-2020
Location: Northern Europe
Member Is Offline
|
|
as far as i know its not possible to create it from ethylene glycol, atleast by reasonable reagents. With HCl (even with CaCl2 or ZnCl2) it just makes
2-chloroethanol and doesnt substitute the other alcohol group. Youd have to make it from ethylene and chlorine gas. Ofc dibromoethane is possible to
make by HBr and glycol, although the yield is bad, i got 48%.
|
|
|
Myrcen
Harmless
Posts: 3
Registered: 28-4-2020
Location: Europe
Member Is Offline
|
|
Quote: Originally posted by RustyShackleford  | as far as i know its not possible to create it from ethylene glycol, atleast by reasonable reagents. With HCl (even with CaCl2 or ZnCl2) it just makes
2-chloroethanol and doesnt substitute the other alcohol group. Youd have to make it from ethylene and chlorine gas. Ofc dibromoethane is possible to
make by HBr and glycol, although the yield is bad, i got 48%.
|
do you have tips for the reaction? i tried making it from glycol i bought at the hardware store. According to the msds it contained mostly ethylene
glycol, 1-3% of boraxpentahydrate and a yellow fluorescent dye, maybe fluorescein. Even with 100 % excess of azeotropic HBr i never got more than 10 %
yield.
|
|
|
RustyShackleford
Hazard to Others
Posts: 200
Registered: 10-12-2020
Location: Northern Europe
Member Is Offline
|
|
I cant speak on the effect of impurities, since i used distilled glycol. But the way i did it was the following:
into a 500ml conical flask was added 154g NaBr (1.5 mol) + 135ml water.
250g H2SO4 95% (2.42 mol) was slowly drizzled in.
36.6g glycol (0.59 mol) added, contents refluxed under stirring for 6h.
mixture was cooled, poured into a separatory funnel, organic layer separated
extracted further with 20ml DCM (mostly to wash out the stuff that stuck to the sides of the sep funnel)
organic phase dried with CaCl2, then distilled
obtained 53g (48%) + 5g seemingly mostly pure that came below bp.
I think the sulfuric acid may be necessary to absorb the water thats released from substitution.
(had a trap with water to catch fumes, since it was letting off a moderate amount of HBr for the first couple hours)
[Edited on 25-10-2021 by RustyShackleford]
|
|
|
Myrcen
Harmless
Posts: 3
Registered: 28-4-2020
Location: Europe
Member Is Offline
|
|
thank you! I think the impurities may be the reason for the low yield, although the hardware store stuff is reasonably pure. I will try it again with
some purer glycol.
|
|
|
macckone
Dispenser of practical lab wisdom
Posts: 2168
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline
Mood: Electrical
|
|
The procedure I am looking at is using ZnCl2, HCl, and ethylene glycol.
Then boiling off the product as it forms to push the reaction rather than refluxing or using a drying agent. The competing reactions form diglycol
ether and dioxane. Using a dehydrating agent like sulfuric acid will push it toward dioxane.
I use a similar reaction for making isopropyl chloride. And it gives very good yield.
|
|
|
Myrcen
Harmless
Posts: 3
Registered: 28-4-2020
Location: Europe
Member Is Offline
|
|
| Quote: Originally posted by macckone | The procedure I am looking at is using ZnCl2, HCl, and ethylene glycol.
Then boiling off the product as it forms to push the reaction rather than refluxing or using a drying agent. The competing reactions form diglycol
ether and dioxane. Using a dehydrating agent like sulfuric acid will push it toward dioxane.
I use a similar reaction for making isopropyl chloride. And it gives very good yield. |
I found a paper from 1881 where Schorlemmer mixed ethylene glycol with an excess of fuming HCl and heated it using a steam bath in a sealed tube. This
procedure gave 1,2-dichloroethane. unfortunately the exact amouns of HCl and glycol are not given.
As Schorlemmer describes in the paper, there are other methods which are using PCl3 or PCl5 and ZnCl2 to chlorinate
the glycol. Pyridine and Thionyl chloride also can be used to form 1,2-dichloroethane.
Attachment: schorlemmer1881.pdf (68kB)
This file has been downloaded 334 times
|
|
|
macckone
Dispenser of practical lab wisdom
Posts: 2168
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline
Mood: Electrical
|
|
Myrcen,
Thanks, that confirms it will work.
It also seems to confirm that ZnCl2 will work as a catalyst.
|
|
|
RustyShackleford
Hazard to Others
Posts: 200
Registered: 10-12-2020
Location: Northern Europe
Member Is Offline
|
|
make sure to run it for a decent while, probably with a decent amount of ZnCl2 and H2SO4. because i recall seeing notes from someone that tried with
just ZnCl2 and HCl, with no wortwhile yield.
|
|
|
SWIM
National Hazard
Posts: 970
Registered: 3-9-2017
Member Is Offline
|
|
@RustyShackleford: That use of a large reservoir pipette as a gas trap is clever.
I haven't seen that before. Compact, simple, prevents suck-back, a handy rig.
|
|
|
lithiumion656
Harmless
Posts: 9
Registered: 21-2-2022
Member Is Offline
|
|
I have been investigating DCE as a high boiling alternative to the now essentially non-OTC DCM, to the extent that producing DCE through this method
is more economical. Has this procedure actually been tried by anyone yet?
|
|
|
ErgoloidMesylate
Banned
Posts: 89
Registered: 8-8-2022
Location: Norad
Member Is Offline
Mood: Freedom of thought is priceless - You can't afford it
|
|
| Quote: Originally posted by lithiumion656 | | I have been investigating DCE as a high boiling alternative to the now essentially non-OTC DCM, to the extent that producing DCE through this method
is more economical. Has this procedure actually been tried by anyone yet? |
By looking to update my first edition also, I actually went back and looked at a reaction I glossed over and actually subbed in one of my chapters,
and i re read and researched and figured it out, and this edition, will not leave it out, but detail the actual synth (not what you would think).
Cannula transfer and cannula filtering is used for lysergic synth Compressed air and remove co2
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
