Hello everybody,
I`m trying to find a syntetic route for p-nitro-benzaldehyde.
I found an article about p-nitro-toluene becoming p-nitro-benzaldehyde, but the yield of the nitration of toluene in the para position is very low,
about 3%. I can work with that, but will be a lot of waste in this route. Any of you guys can help me with that?
Maybe a better synthetic route for p-nitro-toluene...
Thanks
[Edited on 3-5-2017 by stavisoxido]Boffis - 3-5-2017 at 13:11
The yield of p-nitrotoluene from the nitration of toluene is about 30-35%, the problem is separating this isomer from the 60% or so o-isomer and the
various other minor products. There are several methods of oxidation then to the appropriate aldehyde; chromates in acetic acid/acetic anhydride;
condensation with alkyl nitrite/ alkoxides: convert to p-nitrobenyl bromide and then convert to aldehyde with hexamine or similar route etc. If you
are interested I can dig out some refs. I thing I have a summary of methods/review for just this reaction somewhere.Melgar - 3-5-2017 at 14:23
Nitrotoluenes are typically 2, 4, (2,4), or (2,4,6), since alkyl groups are typically ortho/para directing. So that 3% number is probably either
wrong, or a misinterpretation.CuReUS - 4-5-2017 at 03:27
Starting from benzyl alcohol then nitration to make the ortho and para isomers. Then oxydation to nitrobenzaldehyde with MnO2 or simply hypochlorite
with catalyst.
Then distill the mixture to separate the isomers.chemplayer... - 5-5-2017 at 01:27
My experience is that benzyl alcohol + nitric acid at any reasonable concentration generates benzaldehyde and benzoic acid as a result of oxidation.
Vanillin you can nitrate extremely easily as it's a phenol, but not sure about benzyl alcohol - I suspect that the concentration of acid you need to
nitrate will perform the oxidation quite readily.Booze - 6-5-2017 at 10:35
