Chemistry Forums for Students > Organic Chemistry Forum
Ortho-nitration of benzaldehyde
willijung1:
--- Quote from: rolnor on February 19, 2020, 12:22:44 PM ---The two schemes with the alkoxy groups I can understand but the first scheme is strange, it should not work.
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Perhaps it would help to ask the publisher of the procedure..?
Babcock_Hall:
Having recently purchased ortho-nitrobenzaldehyde, I can say that the commercial material was of good quality for our work.
hollytara:
Remember that benzaldehyde in aqueous solution (like nitric acid) is in equilibrium with the hydrate. The hydrate is similar to the acetal - and the acetal is an o-p director (not m), and activating. So the fastest reaction is with the hydrate at the o and p positions!
There is an preference for ortho with benzyl alcohols - a nitrate ester is possible involved with intramolecular nitration at the o position.
Just be careful - when I did some of this chemistry decades ago, the nitrate esters can lower your blood pressure - even being very careful it can be noticeable.
This is the reverse of amines - the amine group is activating o,p; but if protonated to ammonium is deactivating and m.
rolnor:
It seemes strange even so, I think there is something wrong here. Read the wikipedialink I provided its just not possible with just nitric acid and benzaldehyde.
willijung1:
--- Quote from: hollytara on February 20, 2020, 09:46:47 AM ---Remember that benzaldehyde in aqueous solution (like nitric acid) is in equilibrium with the hydrate. The hydrate is similar to the acetal - and the acetal is an o-p director (not m), and activating. So the fastest reaction is with the hydrate at the o and p positions!
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Does benzaldehyde mix well with water? During my experiment, I observed two layers form, so I thought the reason for the failure was because benzaldehyde was not very soluble in water. Thus it couldn't get into the reaction mixture, perhaps...? What should I do to facilitate the process?
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