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Topic: Chlorination of primary non- benzylic amino alcohols  (Read 8006 times)

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Offline java

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Chlorination of primary non- benzylic amino alcohols
« on: December 16, 2006, 06:56:09 PM »
Unable to secure thionyl chloride for the chlorination of a primary amino alcohol I 've been looking for an alternative , as I've looked at the ionic methods , the use of ZnCl +HCl as in the  Lucas test, but for lack of success I 'm open for suggestions, as all the Phosphorous acids are out of reach....java
It's better to die on your feet, than live on your knees.Emiliano Zapata..."Prefiero morir de pie que vivir siempre arrodillado."

Offline proufs

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Re: Chlorination of primary non- benzylic amino alcohols
« Reply #1 on: December 17, 2006, 11:35:56 AM »
Have you tried protecting your amino group with an FMOC or BOC group and then chlorinating via one of the following methods?

1)SOCl2
2)CCl4 with PPh3

And then remove the protecting group with
piperdine in DMF for the FMOC
-or-
TFA in dichloromethane at room temp for the BOC

By the way, I can't tell if you are saying you can't obtain the chloride from SOCl2 or if you can't use SOCl2 because you don't have access to the chemical.  As you probably know SOCl2 is the most straightforward and reliable method to convert primary alcohols to alkyl chlorides.

Let me know if this doesn't help and I'll help you out with another protocol.

Offline java

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Re: Chlorination of primary non- benzylic amino alcohols
« Reply #2 on: December 17, 2006, 02:37:43 PM »
In an acidic environment ,one doesn't need to protect the amino group, and the reason I can't use thionly chloride or any of the phosphorous acids is because I have no access to them.

"TFA in dichloromethane at room temp for the BOC" so do you have any references for this method, and the separation from the halide post reaction and it's limitations....also since it's in an acidic environment why would one need to protect the amine group...java
It's better to die on your feet, than live on your knees.Emiliano Zapata..."Prefiero morir de pie que vivir siempre arrodillado."

Offline proufs

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Re: Chlorination of primary non- benzylic amino alcohols
« Reply #3 on: December 17, 2006, 05:46:24 PM »
You are right, you don't need to protect the amine unless you have to worry about the free amine  reacting with your thionyl chloride which you won't be using, or if you are concerned about isolating the amine in workup.  I guess it really depends on the rest of the molecule.

I guess you could make it from bubbling HCl gas through a syringe (don't use one with a rubber plunger) into ether at low temp(table salt in an ice bath (-10C) slurry is probably cold enough) with plently of ventilation if your substrate is somewhat soluble in ether.  Again, depends on the molecule.  You can make the HCl gas...  try this: http://mattson.creighton.edu/HCl/
It's a lot of extra work but everything you need is cheap and can be purchased from either a drug store or a hardware store.  It might take some imagination and practice to get a reliable set up.

Boc deprotection:
http://www.emdbiosciences.com/SharedImages/TechnicalLiterature/6_boccleavage.pdf

Just curious...Where are you doing synthetic chemistry that you don't have access to thionyl chloride or triphenylphosphine?  I believe they are both cheap and readily available.

Offline java

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Re: Chlorination of primary non- benzylic amino alcohols
« Reply #4 on: December 17, 2006, 07:08:13 PM »
With the political climate and a terrorost behind every shadow, any chemical that can be used for a weapon is watched and the buyer is scrutinized ..the way of the home hobbiest is on the way out , ..I do however appreciate the tip on using TFA as I will have to find the working paramenters, as for the gas and the syringe method ...remember this is a primary alcohol it doesn't chlorinate as easy as a tertiary alcohol or a socondary for that matter.....in the back burner I have the synthesis for thionyl chloride but wish to avoid the well know gasping gas it produces with mere moisture in the air....java

Edited: I started rambling so I edited out the superflous material..
« Last Edit: December 18, 2006, 06:29:56 AM by java »
It's better to die on your feet, than live on your knees.Emiliano Zapata..."Prefiero morir de pie que vivir siempre arrodillado."

Offline java

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Re: Chlorination of primary non- benzylic amino alcohols
« Reply #5 on: December 21, 2006, 03:27:07 PM »
On a related note ,will the reduction with I2/Hypophosphorous acid and a pimary amino alcohol affect the amino group as the OH is being reduced to the hydrocarbon?

Note: the answer is no.....and the Hypo/I2 will  reduce a primary alcohol to the hydrocarbon 
« Last Edit: March 28, 2007, 10:52:52 AM by java »
It's better to die on your feet, than live on your knees.Emiliano Zapata..."Prefiero morir de pie que vivir siempre arrodillado."

Offline Mr. Jack

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Re: Chlorination of primary non- benzylic amino alcohols
« Reply #6 on: December 07, 2007, 04:52:24 AM »
I have been looking for alternate methods to chlorinate secondary, aliphatic amino alcohols (eg 1-amino-2-butanol).  Of course the most celebrated method is thionyl chloride.  Another I have come across is the use of cyanuric chloride (TCA) and dimethylformamide (DMF).  I am, however, more interested in a more "OTC" method.

I was wondering how I might expect the chlorination to proceed using HCl as the reagent.  Also, what if the amino group was further protected with a methyl group or maybe two?  Would there be dehydration products (ethers) like those encountered when reacting primary alcohols with the hydrohalogen acids (eg HBr + EtOH -> EtBr + Et2O + H2O)?

Yes, I know that equation is not balanced.
« Last Edit: December 07, 2007, 03:23:57 PM by Mr. Jack »

Offline Mr. Jack

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Re: Chlorination of primary non- benzylic amino alcohols
« Reply #7 on: May 01, 2008, 12:36:50 AM »
It's been some time and noone has replied so...

A professor told me that Lucas' Reagent should work (ZnCl2 + HCl) with a secondary amino alcohol (in lower yields, of course) producing the HCl salt of the chloro-aminoalkane.

Any thoughts?

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