ORGLIST: Re: piperazine et al.

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From: Jacob Zabicky (jzabicky$##$etseq.urv.es)
Date: Fri Oct 02 1998 - 12:07:07 EDT


Hello!

Prompted by the reply of Richard Prankerd
<richard.prankerd$##$pharmacy.uq.edu.au> I would like to send to the list a
similar response with a couple of added suggestions I've sent directly to
Roshan Deen <roseview$##$hotmail.com>

Hello Roshan,

I wouldn't say that your reaction doesn't work, it works too well, so that
you cannot stop at the first stage and you carry on to the second one. I
have some experience with reactions that you want to stop half the way, but
not with your particular one. However, I may propose you try the following
long shot schemes, because they can work, and after having had the first
N-alkylation, the second one would be slowed down by deactivation.

1. The first suggestion would be to carry out your reaction without a base.
You could get with some luck N-propylpiperazonium bromide, and the ammonium
center will deactivate the second near-by amine, leading preferentially to
monoalkylation. After you finish you can neutralize and isolate your
products.

2. The second one would be putting some propyl bromide and an excess of
piperazine in a laboratory ball mill and let it go overnight. You may have
some technical difficulties to avoid spillage or evaporation, but they can
easily be overcome. The results may be surprising.

Let me know, please, the results if you ever try any such scheme.

All the best

Jacob


>In reply to the following:
>>
>>
>>Dear pals,
>>Could any one suggest me why the following reaction does not work.
>>1. I have reacted piperazine (2 mole) with n-propyl bromide (1 mole) to
>>give n-propyl piperazine. The reaction was carried out in ethanol (under
>>reflux)with 1 mole of NaOH for 7 hrs. Unfortunately, what i obtained
>>was the disubstituted product and unreacted piperazine.
>>
>>I could be much greatly if you'll could offer me other procedure to
>>synthesize the above mentioned compound. I would also like to know on
>>the commercial availability of theis compound. Any other suggestion is
>>welcome.
>>



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Prof. Jacob Zabicky Fax. xx-34-977-559694
c/o Prof. Alberto Coronas Tel. xx-34-977-559696
Department of Mechanical Engineering Private No.
Universitat Rovira i Virgili xx-34-930-119552
Cra. de Salou s/n
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