subsecret
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Would This Work: 2,2-dichlorobutane from MEK
I intend to prepare 2,2-dichlorobutane from MEK and an excess of HCl, with a zinc chloride catalyst. I'm not sure if the second stage of the reaction
is possible.
Here's the scheme:
First, HCl reacts with MEK to form 2-chlorobutan-2-ol.
Normally, with 2-butanol for example, the alcohol's O atom has enough electron density to do a nucleophilic attack on an HCl molecule, protonating
the alcohol, which then leaves as water. Next, the chloride is able to attack the resulting secondary carbocation, in this case forming
2-chlorobutane.
This is where I'm stuck: In 2-chlorobutan-2-ol, the chlorine and the alcohol group share that #2 carbon, where the chlorine pulls electron density
away from the alcohol. I'm not sure whether 2,2-dichlorobutane will be able to form, as I'm not sure that the alcohol will become protonated. I
suspect that the reaction doesn't proceed this way, as I was unable to find the 2,2-dichlorobutane in several organic chemistry PDFs.
Any help is appreciated.
Fear is what you get when caution wasn't enough.
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DraconicAcid
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I doubt it. 2-chloro-2-butanol will spontaneously eliminate HCl to give butanone (MEK).
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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UC235
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No, this won't work at all. You need far more powerful chlorinating agents than Lucas reagent to make a ketone into a geminal dihalide. You'll only
get acid catalyzed aldol condensations using these reaction conditions.
Instead you need to use a far more oxophilic chlorinating reagent. PCl5 will work, as will the product of chlorinating triphenylphosphine.
There's a chance that you might make treatment with benzotrichloride (or perchloropropylene) and a lewis acid work, but definetly don't quote me on
that. It might still make a mess with an enolizable ketone.
[Edited on 30-12-2014 by UC235]
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subsecret
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Thanks for the input. I made the beginner mistake of getting excited about this before I figured out if it would work. 
Wait, you're not UC
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UC235
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Yes, I am. I got locked out of my normal account due to a password issue and am waiting for Polverone to get back to me about sorting it out.
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subsecret
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Sorry 
Fear is what you get when caution wasn't enough.
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CuReUS
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what would you get if you did free radicle substitution of malonic acid with excess chlorine ?
would you get 2,2-dichloromalonic acid ?
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