Tropolone

Tropolone

Names
IUPAC name 2-Hydroxy-2,4,6-cycloheptatrien-1-one
Other names 2-Hydroxytropone; Purpurocatechol
Identifiers
CAS Number	533-75-5 Y
3D model (Jmol)	Interactive image
ChemSpider	10333 N
EC Number	208-577-2
KEGG	C15474 N
MeSH	D014334
PubChem CID	10789
UNII	7L6DL16P1T N
InChI InChI=1S/C7H6O2/c8-6-4-2-1-3-5-7(6)9/h1-5H,(H,8,9) N Key: MDYOLVRUBBJPFM-UHFFFAOYSA-N N InChI=1/C7H6O2/c8-6-4-2-1-3-5-7(6)9/h1-5H,(H,8,9) Key: MDYOLVRUBBJPFM-UHFFFAOYAW
SMILES C1=CC=C(C(=O)C=C1)O
Properties
Chemical formula	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)
Magnetic susceptibility (χ)	-61·10−6 cm3/mol
Hazards
S-phrases	S22 S24/25
Flash point	112 °C (234 °F; 385 K)
Related compounds
Related compounds	Hinokitiol (4-isopropyl-tropolone)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
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.

Many methods have been described for the synthesis of tropolone. 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. With metal cations, it undergoes deprotonation to give chelate complexes, e.g., Cu(O₂C₇H₅)₂.

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.

It is an inhibitor of grape polyphenol oxidase and mushroom tyrosinase.