Tropolone
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| Names | |||
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| IUPAC name
2-Hydroxy-2,4,6-cycloheptatrien-1-one
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| Other names
2-Hydroxytropone; Purpurocatechol
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| Identifiers | |||
533-75-5  |
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| 3D model (Jmol) | Interactive image | ||
| ChEMBL | ChEMBL121188  |
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| ChemSpider | 10333 |
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| EC Number | 208-577-2 | ||
| KEGG | C15474 |
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| MeSH | D014334 | ||
| PubChem | 10789 | ||
| UNII | 7L6DL16P1T |
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| Properties | |||
| C7H6O2 | |||
| Molar mass | 122.12 g/mol | ||
| Melting point | 50 to 52 °C (122 to 126 °F; 323 to 325 K) | ||
| Boiling point | 80 to 84 °C (176 to 183 °F; 353 to 357 K) (0.1 mmHg) | ||
| Acidity (pKa) | 6.89 (and -0.5 for conjugate acid) | ||
| Hazards | |||
| S-phrases | S22 S24/25 | ||
| Flash point | 112 °C (234 °F; 385 K) | ||
| Related compounds | |||
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Related compounds
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Hinokitiol (4-isopropyl-tropolone) | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 verify (what is ?) |
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| Infobox references | |||
Tropolone is an organic compound with the formula C7H5(OH)O. It is a pale yellow solid that is soluble in organic solvents. The compound has been of interest to research chemists because of its unusual electronic structure and its role as a ligand precursor. Although not usually prepared from tropone, it can be viewed as its derivative with a hydroxyl group in the 2-position.
Synthesis and reactions[edit]
Many methods have been described for the synthesis of tropolone.[2] One involves bromination of 1,2-cycloheptanedione with N-bromosuccinimide followed by dehydrohalogenation at elevated temperatures and by acyloin condensation of the ethyl ester of pimelic acid the acyloin again followed by oxidation by bromine.
The compound readily undergoes O-alkylation to give cycloheptatrienyl derivatives, which in turn are versatile synthetic intermediates.[3] With metal cations, it undergoes deprotonation to give chelate complexes, e.g., Cu(O2C7H5)2.
Natural occurrence[edit]
Many natural products contain the tropolone skeleton. These include puberulic acid, stipitatonic acid, stipitatic acid, puberulonic acid, sepedonin, and theaflavins of black tea. It arises via a polyketide pathway, which affords a phenolic intermediate that undergoes ring expansion.[3]
Biological effects[edit]
It is an inhibitor of grape polyphenol oxidase[4][5] and mushroom tyrosinase.[6]
References[edit]
- ^ Tropolone at Sigma-Aldrich
- ^ Richard A. Minns "Tropolone" Org. Synth. 1977, volume 57, 117.doi:10.15227/orgsyn.057.0117
- ^ a b Pietra, F., "Seven-membered conjugated carbo- and heterocyclic compounds and their homoconjugated analogs and metal complexes. Synthesis, biosynthesis, structure, and reactivity", Chemical Reviews 1973, volume 73, 293-364. doi:10.1021/cr60284a002
- ^ Time-dependent inhibition of grape polyphenol oxidase by tropolone. Edelmira Valero, Manuela Garcia-Moreno, Ramon Varon and Francisco Garcia-Carmona, J. Agric. Food Chem., 1991, volume 39, pp. 1043–1046, doi:10.1021/jf00006a007
- ^ Chedgy, Russell. Secondary metabolites of Western red cedar (Thuja plicata): their biotechnological applications and role in conferring natural durability. LAP Lambert Academic Publishing, 2010, ISBN 3-8383-4661-0, ISBN 978-3-8383-4661-8
- ^ Inhibition of mushroom tyrosinase by tropolone. Varda Kahn and Andrawis Andrawis, Phytochemistry, Volume 24, Issue 5, 1985, Pages 905-908, doi:10.1016/S0031-9422(00)83150-7
