RE: ORGLIST:

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From: Pere Lloveras (litrans$##$bcn.servicom.es)
Date: Wed Oct 07 1998 - 12:38:33 EDT


Barnabas,

1) When there are o/p activating groups, the meta effect of CHO is no
sense:-(
2) When there are several activating groups pointing to different positions,
     Murphy's law prevails over any other ;-)

Regards.
Pere

-----Original Message-----
De: barnabas liau <barnabas_liau$##$hotmail.com>
Para: Multiple recipients of list orglist <orglist$##$dq.fct.unl.pt>
Fecha: miircoles 7 de octubre de 1998 10:44
Asunto: ORGLIST:


>Dear colleagues,
>i read of an article, syn comm 23(10),1351-1356(1993)and am quite
>puzzled with the results obtained.the following is the summary of the
>paper:
>Nitration of 2,5- Dimethoxybenzaldehyde [ named as A]
>
>1) A ---------.> 3,5- Dimethoxy-2-nitrobenzaldehyde (64%) +
> 2,5- Dimethoxy-4-nitrobenzaldehyde (26%)
>
>2) A----------> MIXTURE OF mono, di and trinitro compound
>
>3) A----------> 3,5- Dimethoxy-2-nitrobenzaldehyde (60%) +
> 2,5- Dimethoxy-4-nitrobenzaldehyde (29%) +
> 2,5- Dimethoxy-3-nitrobenzaldehyde (5%)
>condition for
>1)70% HNO3 as solvent and nitrating agent, stirred at RT for 3 hrs.
>3)70 % HNO3 Et20 as solvent + acetic acid, stirred at RT for 30 hrs.
>my question is ,
>why should 3,5- Dimethoxy-2-nitrobenzaldehyde be the major compound in
>both cases in viewof the fact that it may be affected by steric
>hindrance.(moreover -CHO is a meta director)
>my opinion is 2,5- Dimethoxy-3-nitrobenzaldehyde should be the major
>product.
>could anyone please offer me some possible explanation? and is there any
>other condition where one can get
>2,5- Dimethoxy-3-nitrobenzaldehyde as major product?


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