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Author: Subject: Retrofinkelstein reaction (baseless inquiry)
Opylation
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[*] posted on 2-6-2021 at 23:59
Retrofinkelstein reaction (baseless inquiry)


So, let me start this by saying my mind wonders when thinking of solutions to unasked questions. I was trying to find an easy way to form dichloroethane (I know, ethylene and chlorine) without all the hassle of using gaseous reagents and quickly crossed off any sort of coupling reaction with chloroform. I know it may be tremendously easier to just purchase the solvent outright but where is the fun in that. Also, I find it difficult to justify spending $75 (with shipping and hazards fees) to purchase 500ml, which could be chalked up to being a cheap bastard. So I decided to scour the interwebs for an alternate solution and came across the undergraduate lab of testing for alkenes. You know, the dehydration of ethanol to ethylene and then testing your gas with aqueous bromine/iodine. Well I happen to have about a liter of saturated aqueous iodine, from when I made elemental iodine, that's been collecting dust for quite some time that I thought could be put to use. So that got me to thinking, maybe I could bubble ethylene through that and make diiodoethane. Beyond that I got to thinking how I could go about using diiodoethane to make dichloroethane.

I found an interesting paper on the reverse Finkelstein reaction of aromatic rings and they cited Cupric Halides as their reagent. They used some novel solvent 1-Butyl-3-methylimidazolium halide which I can go out on a limb and say is not readily accessible. Also, being that the paper is specifically regarding aromatic rings, this doesn't help me. But, I was thinking back to the Finkelstein reaction and its use of mass action to forward the reaction. Curiously, Cuprous Iodide is insoluble in dilute acids and barely soluble in plain water. Also, Cupric Iodide is not an ionic compound, or at least one that is prepared easily at STP.

I am curious as to whether a reaction of aliphatic alkyl iodides could be used, with CuCl2 in HCl acid, in a reverse Finkelstein reaction. Refluxing the aliphatic alkyl iodide with CuCl2 in hydrochloric acid would, if there was a reaction, produce CuI, which in turn would precipitate out of solution. Kind of like the Finkelstein reaction. Again, just like my subject states, this is a baseless inquiry with no examples or evidence to go on. Just curious as to what insight you all may provide me
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draculic acid69
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[*] posted on 3-6-2021 at 01:01


1,1 Dichloroethane or 1,2dichloroethane?
1,2dce could be made from ethylene glycol and zncl+HCL.

Also I've been wondering if the ene+ HCL rxn can be done
by bubbling the ene thru aqueous HCL or if it needs to be gas phase
or high temps or can it be done at room temperature. Cylinders of propylene
and liters of HCL are otc
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[*] posted on 3-6-2021 at 01:33


I was referring to 1.2-dichloroethane. I was under the impression that ethylene glycol + HCl makes ethylene chlorohydrin, but then again, I also thought that was without ZnCl2. Interesting then, that would be way easier. I have a decent amount of distilled ethylene glycol I can put to use. As a side note, that stuff is a pain to distill from antifreeze. I’ve had it bump up through a Vigreaux column into the receiving flask. Now that you mention it though, I think I’ve read something about ZnCl2 and HCl. I’m not sure if I’m mixing up my reactions but if I remember correctly it has to be concentrated HCl and ZnCl2. Ah, a brief search shows you’re talking about the Lucas reaction. That goes to show I’ll overcomplicate anything haha

Edit: changed oversimplify to overcomplicate. Wrote this as I was going to bed... major durp

[Edited on 3-6-2021 by Opylation]
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draculic acid69
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[*] posted on 4-6-2021 at 01:47


Maybe your right about the chlorohydrin thing I was just generalising that OH groups+HCL W/zncl should give the halide in theory. Definitely research it a bit more before taking my word for it. Just bcoz it works with ethanol doesn't guarantee that the glycol will behave the same. Having those two hydroxyls next to each other
makes things more complicated.
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