From: Amir Mahmoudkhani (amirmahmoudkhani$##$hotmail.com)
Date: Wed May 28 2003 - 01:15:07 EDT
Hi Palash,
Some of chlorinated solvents such as CH2Cl2 and CHCl3, contain HCl (even at
ppm level), which can eventually form a salt with pyridine upon standing.
You may distil the solvent over alumina before use. Do a simple test,
needles must dissolve in water!
Yours,
Amir
>From: Palash <Palash.Gangopadhyay$##$fys.kuleuven.ac.be>
>To: <everybody$##$orglist.net>
>Subject: ORGLIST:Dichloromethane
>Date: Mon, 26 May 2003 13:46:00 +0200
>
>Dear collegues
>
>Dichloromethane (HPLC, Aldrich) with 1% pyridine (AR grade, Aldrich)
>produces white needle shaped crystals on standing for two weeks! Has
>anybody experience such problem before? That mixture is used as solvent in
>one of my collegues's experiment here! Sometime back I also noticed one
>more problem with dichloromethane : when I was purifying N, N'
>dibenzylcyclohexane diamine thru a basic alumina column in dichloromethane,
>what I got back was the two amino nitrogen connected with a CH2, forming a
>ring. It was pretty good reproducing, stir the amine with DCM in activated
>basic alumina for 24 hours at room temperature and the ring is closed (I
>have even the crystal structure). I wonder what happens there actually?
>
>Best regards
>palash
>
>*******************************************************
>Dr. Palash Gangopadhyay
>Laboratory for Chemical and Biological Dyanamics
>Department of Chemistry, K U Leuven
>200 D Celestijnenlaan
>B 3001 Heverlee, Leuven
>Belgium
>Phone # 003216327169
>email: palasgangopadhyay$##$yahoo.com
>********************************************************
>
>
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