Chemical screw-up: failed arylation of acetylacetone
For your amusement, an entry in the series "Kitchen Disasters":
Some time ago we discussed the synthesis of phenylacetones by arylation of acetylacetone: https://www.sciencemadness.org/whisper/viewthread.php?tid=16...
After some tuning (use more acid in workup to avoid the copious amounts of KH2PO4 precipitate!), it works quite good with PhBr, but the large amount
of base needed seems not worth the trivial product.
So an attempt was made at performing the reaction on 2-iodo-hydroquinonedimethylether, despite the original paper stating that it does not work with
ortho-substituents. The reaction was performed and worked up in the usual ways. The residue was distilled in vacuo to give a dark red fraction boiling
at 135°C with a peculiar smell. The high boiling fraction was discarded.
A few weeks later, the low boiling fraction was analyzed: It's 2-hydroxy-4,6-dimethylacetophenone. Imagine the amusement when the chemist realized
what happened! 
(Posting here instead of Beginnings since there is such an influx of boring school chemistry)
Edit: Should have added - the fraction is far from pure. It has a melting point below RT.
Edit 2: More analytics: low boiling fraction probably also contains either p-dimethoxybenzene or the iodo-derivate and minor amounts of the desired
phenylacetone. (dimethoxybenzene/iododimethoxybenzene:2-hydroxy-4,6-dimethylacetophenone:phenylacetone ~ 2:1:0.3)
[Edited on 4-6-2012 by turd]
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