From: Sandra Bartoli (sandy13_1$##$hotmail.com)
Date: Thu Mar 09 2006 - 13:55:50 EST
Hi,
Zn/CH3COOH/ H2O (10 eqs of Zn, 9:1 CH3COOH/H2O, water is necessary for the
reaction to go) reduces the nitro group smoothly and it also reduces the
formyl. You have to be careful, because with an aldehyde and a nitro you
could get the reductive amination product(s), and that is why hydrogenation
would not be the best choice anyway. I suggest to reduce the aldehyde before
reducing the nitro group, as if you reduce the nitro to the amine it can
form the imine condensing with the aldehyde (and I bet it forms it quite
quickly) which then gets reduced to the amine and you do not get what you
want or anyway you get a dirty reaction.
Try reducing the aldehyde with NaBH4 before, and then reduce the nitro with
Zn.
Hope it helps.
Sandra
>From: diogo$##$unilavras.edu.br
>To: everybody$##$orglist.net
>Subject: ORGLIST: nitroarene reduction
>Date: Thu, 9 Mar 2006 11:35:01 -0300 (BRT)
>
>Hi, everybody!
>Thereīs been a long time since Iīm trying to reduce some nitro derivatives
>of vanillin. we arenīt able to do it by catalytic hydrigenation since we
>donīt have the reagent and apparatus. But Iīve been searching some methods
>in literature and Iīm quite envolved with borohydride-transition metal
>nitro reduction. Besides reducting the nitro group and the formyl group
>(also present in the molecule) there have been many other byproducts, I
>guees degradation. I would appreciate if you could sugest ways to overcome
>this and get the pure aromatic amino and maybe even not the reducted
>formyl group. other reduction systems are quite welcome.
>Diogo
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