Talk:Pechmann condensation
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The file "Pechmann umbelliferone.png" contains as first stap in the reaction the loss of both carbondioxide AND water. When I count it in the correct way the loss of those two molecules from malic acid (C4H6O5) will deliver a molucule with the formula C3H4O2, hardly in accordance with the one for formylacetic acid (C3H4O3). Decarboxylation of the malic acid wil give 3-hydroxypropionic acid, which might loose, under the infuence of sulfuric acid, the molecule of water giving rise to acrylic acid. This later acid is very well capable of reacting with an electrophilc aromatic compound. To form formylacitic acid an oxidation has to take place on 3-hydroxypropionic acid. So I think there's something not quite well in the drawing, or my common sence on chemistry is not as well as I thought it is. T.vanschaik (talk) 19:46, 7 March 2009 (UTC)
- Actually the first step involves decarbonylation, not decarboxylation - carbon monoxide is lost, not carbon dioxide. So I think the equation matches up OK. A few carboxylic acids do that sort of thing - for example oxalic acid, if I recall correctly, loses CO and CO2 when heated with sulfuric acid. Walkerma (talk) 20:50, 7 March 2009 (UTC)