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- Pechmann_condensation abstract "The Pechmann condensation is a synthesis of coumarins, starting from a phenol and a carboxylic acid or ester containing a β-carbonyl group. The condensation is performed under acidic conditions. The mechanism involves an esterification/transesterification followed by attack of the activated carbonyl ortho to the oxygen to generate the new ring. The final step is a dehydration, as seen following an aldol condensation. It was discovered by the German chemist Hans von Pechmann .With simple phenols, the conditions are harsh, although yields may still be good.With highly activated phenols such as resorcinol, the reaction can be performed under much milder conditions. This provides a useful route to umbelliferone derivatives:For coumarins unsubstituted at the 4-position, the method requires the use of formylacetic acid or ester. These are unstable and not commercially available, but the acid may be produced in situ from malic acid and sulfuric acid above 100 °C. As soon as it forms, the formylacetic acid performs the Pechmann condensation. In the example shown, umbelliferone itself is produced, albeit in low yield:".
- Pechmann_condensation thumbnail Pechmann_4methyllcoumarin.png?width=300.
- Pechmann_condensation wikiPageID "2404284".
- Pechmann_condensation wikiPageLength "3405".
- Pechmann_condensation wikiPageOutDegree "23".
- Pechmann_condensation wikiPageRevisionID "696679759".
- Pechmann_condensation wikiPageWikiLink Aldol_condensation.
- Pechmann_condensation wikiPageWikiLink Carbonyl.
- Pechmann_condensation wikiPageWikiLink Carboxylic_acid.
- Pechmann_condensation wikiPageWikiLink Category:Condensation_reactions.
- Pechmann_condensation wikiPageWikiLink Category:Name_reactions.
- Pechmann_condensation wikiPageWikiLink Chemist.
- Pechmann_condensation wikiPageWikiLink Chromone.
- Pechmann_condensation wikiPageWikiLink Coumarin.
- Pechmann_condensation wikiPageWikiLink Ester.
- Pechmann_condensation wikiPageWikiLink Germany.
- Pechmann_condensation wikiPageWikiLink Hans_von_Pechmann.
- Pechmann_condensation wikiPageWikiLink Kostanecki_acylation.
- Pechmann_condensation wikiPageWikiLink Malic_acid.
- Pechmann_condensation wikiPageWikiLink Perkin_reaction.
- Pechmann_condensation wikiPageWikiLink Phenol.
- Pechmann_condensation wikiPageWikiLink Phosphorus_pentoxide.
- Pechmann_condensation wikiPageWikiLink Resorcinol.
- Pechmann_condensation wikiPageWikiLink Sulfuric_acid.
- Pechmann_condensation wikiPageWikiLink Umbelliferone.
- Pechmann_condensation wikiPageWikiLink File:Pechmann_4methyllcoumarin.png.
- Pechmann_condensation wikiPageWikiLink File:Pechmann_4methylumbelliferone.png.
- Pechmann_condensation wikiPageWikiLink File:Pechmann_umbelliferone.png.
- Pechmann_condensation wikiPageWikiLinkText "Pechmann condensation".
- Pechmann_condensation wikiPageUsesTemplate Template:Reflist.
- Pechmann_condensation subject Category:Condensation_reactions.
- Pechmann_condensation subject Category:Name_reactions.
- Pechmann_condensation hypernym Synthesis.
- Pechmann_condensation type ProgrammingLanguage.
- Pechmann_condensation type Eponym.
- Pechmann_condensation type Reaction.
- Pechmann_condensation comment "The Pechmann condensation is a synthesis of coumarins, starting from a phenol and a carboxylic acid or ester containing a β-carbonyl group. The condensation is performed under acidic conditions. The mechanism involves an esterification/transesterification followed by attack of the activated carbonyl ortho to the oxygen to generate the new ring. The final step is a dehydration, as seen following an aldol condensation.".
- Pechmann_condensation label "Pechmann condensation".
- Pechmann_condensation sameAs Q900411.
- Pechmann_condensation sameAs Pechmann-Reaktion.
- Pechmann_condensation sameAs Condensación_de_Pechmann.
- Pechmann_condensation sameAs تراکم_پچمان.
- Pechmann_condensation sameAs ペヒマン縮合.
- Pechmann_condensation sameAs m.079qz5.
- Pechmann_condensation sameAs Q900411.
- Pechmann_condensation sameAs Pechmann缩合反应.
- Pechmann_condensation wasDerivedFrom Pechmann_condensation?oldid=696679759.
- Pechmann_condensation depiction Pechmann_4methyllcoumarin.png.
- Pechmann_condensation isPrimaryTopicOf Pechmann_condensation.