From: owner-orglist$##$dq.fct.unl.pt
Date: Fri May 12 2000 - 05:15:23 EDT
I have a different (possible) explanation. This is learnt (the hard way)
from our undergraduate lab class. The reaction with acids should go smoothly
(colour change trivial as was suggested), however, the success of the
reaction does hinges on the work-up step. You have to make sure all traces
of acid used in the reaction are thoroughly removed from your crude product
(by successive washing with carbonate solution, for example). If not, when
you distil the product alcohol in the purification, the acid could
re-protonate your OH, and eliminates to give your alkene back again, leaving
a smothering char behind!!
Hope this suggestion is helpful, and good luck!
Mimi Hii
Dr. King Kuok (Mimi) Hii
Department of Chemistry
King's College London
Strand
London WC2R 2LS
email: mimi.hii$##$kcl.ac.uk
tel: +44 (0)207-8481183
fax: +44 (0)207-8482810 or +44 (0)870-0636196
-----Original Message-----
From: owner-orglist$##$dq.fct.unl.pt [mailto:owner-orglist$##$dq.fct.unl.pt] On
Behalf Of Jacob Zabicky
Sent: 09 May 2000 12:00
To: Multiple recipients of list orglist
Subject: Re: ORGLIST: Secondary alcohol from alkene
Hello William,
1. It goes with the trade! A good organic chemist is never affraid of color
developing in a concoction. Perhaps--a very reserved perhaps--on using
reagents of very high purity or working under special conditions, such as
total darkness or avoiding the presence of oxygen, this can be reduced or
avoided.
2. Check if your reagents are realy what you think they are. Old stuff can
be very deteriorated and should be purified or disposed of.
All the best,
Jacob
>Dear All
>
> I am trying to make a secondary alcohol from alkene by using either H2SO4
>or HClO4 as catalyst with Formic acid. I found some literatures about this
>reaction but my experiment was unsuccessful. There are two questions that I
>want to ask
> 1. Every time I reflux the reaction the colour always changes to dark
>brown. Is there any way I can avoid it?
> 2. How do I control the reaction condition since it seems that nothing
>had happened in my own reaction?
> The literature was published in 1953 (or 1955 on JACS) (the one I
found)
>but I don't have it with me at the moment. I will put it up if anyone want
>to know the exact detail.
>
>Thanks for help
>
>
>William Chien
>9-5-00
>
>
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