Re: ORGLIST: amidation using DCC/DIC

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From: will jones (willjones46$##$hotmail.com)
Date: Sat Apr 28 2007 - 11:32:46 EDT


Ohad,

What you want to do is pretty straight forward. As for how you do it, is
down to experimentation.
Acylation reactions in aqueous phase can be low yielding as water itself is
a nucleophile, and so will hydrolyse you activated ester. Saying that
though, it is possible as I used to do it all the time...

>>From previous experience, I would do the following:

DDC+carboxylic acid+NHS(2eq).

in organic solvent. DDC will produce an insoluble DCU product that you can
filter off before adding your activated ester straight to your ammonia
solution.

As for purification, the ammonia can be evaporated off, the carboxylic acid
extracted by acid/base extraction. How the NHS can be removed depends
completely on what your carboxylic acid is.

You alternative is to carry out the whole thing in dioxane, as NH3 in
dioxane can be bought from sigma.

Dont bother with the acid chloride as this will hydrolyse really easily in
water. In organic solvent, that's a different story, but I would always go
for DDC/NHS for ease.

Hope that makes sense.

Will

>From: "Ohad Ilovich" <ilovich$##$pob.huji.ac.il>
>To: <everybody$##$orglist.net>
>Subject: ORGLIST: amidation using DCC/DIC
>Date: Thu, 26 Apr 2007 16:35:28 +0200
>
>Dear all
>
>I wish to preform an amidation reaction on a carboxylic acid. This can be
>done in two ways i know of:
>1) creation of the acid chloride and then a reaction with the amine
>2) direct reaction with an amine in the presance of a dehydrating agent
>such as DCC or DIC.
>I wish to do the amidation with ammonia but it is expensive so i thought of
>using ammonium hydroxide in an aqueous phase.
>Does anyone have any expirience with these reagent? any articles in the
>subject?
>by the way i'm not working in solid phase....
>Thanks in advance
>Ohad Ilovich
>
>
>
>
>
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