From: will jones (willjones46$##$hotmail.com)
Date: Wed May 24 2006 - 04:49:16 EDT
I carry out thioether reactions all the time in the presence of amine groups
without any real problems. Under aqueous conditions, the amine groups are
protonated and the -SH is a better nucleophile, and so you get preferencial
thioether formation.
As far as the halogen goes, go for an iodo.
So, provided your reagents are soluble in water, the conditions I use are as
follows:
Dissolve thioether in 0.01M citric acid buffered (or I guess acetic acid) pH
6.5 water. Do the same with your iodoalkyl chain. Keep the whole thing in
the dark as the light will cause degradation of your alkyl.
You limiting factor is the solubilty of your compounds in water. You could
try adding a bit of DMSO or DMF to solubilise your alkyl. I dont know how
what ratio you can use before you start getting the amine reacting with the
halogen. Try using as little DMSO or DMF as possible and see if the reaction
works.
If you use the conditions you use (NaH, THF), then you'll get the amine
group reacting as well.
Hope that helps.
Will
>From: anupam mathur <anupam_14$##$yahoo.com>
>To: everybody$##$orglist.net
>Subject: ORGLIST: thioether formation
>Date: Tue, 23 May 2006 05:04:10 -0700 (PDT)
>
>Hi!
>
>I want to prepare a thioether using cysteine and long
>chain alkyl halide in presence of sodium hydride(2
>eq.) in THF. does amino acid and carboxylic acid
>present on cysteine effect the reaction in some way.
>is there any other alternative way to prepare a
>thioether using cysteine and long chain alkyl
>halide.how much does the chain length effect the
>reactivity of formation of thioether bond.any
>suggestions. please do help.
>thanks in advance,
>anupam
>
>
>anupam mathur
>c/o Dr. k. k. mathur
>115/293, old haider ganj
>Lucknow-226003
>#(0522)263675
>Uttar Pradesh
>email-id anupam_14$##$yahoo.com
>
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