Umbelliferone
IUPAC name	7-Hydroxychromen-2-one
Other names	7-Hydroxycoumarin
Identifiers
CAS number	93-35-6 Y
PubChem	5281426
SMILES	O=C1OC2=C(C=CC(O)=C2)C=C1
Properties
Molecular formula	C9H6O3
Molar mass	162.14 g/mol
Melting point	230 °C (decomposes)
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Umbelliferone or 7-hydroxycoumarin is a widespread natural product of the coumarin family. It occurs in many familiar plants from the Apiaceae (Umbelliferae) family such as carrot, coriander and garden angelica, as well plants from other families such as the mouse-ear hawkweed. It is a yellowish-white crystalline solid which has a slight solubility in hot water, but high solubility in ethanol. It absorbs ultraviolet light strongly at several wavelengths. Despite several indications that this chemical is photomutagenic it is used in sunscreens.^[1]

[edit] Chemical synthesis

Umbelliferone is traditionally synthesized using the Pechmann condensation, from resorcinol and formylacetic acid (generated from malic acid in situ).

A newer synthesis uses methyl propiolate and a palladium catalyst.

[edit] Ultraviolet fluorescence

Umbelliferone absorbs strongly at 300, 305 and 325 nm, with log ε values of 3.9, 3.95 and 4.15 respectively, and it fluoresces blue in both ultraviolet and visible light. The powerful absorption at three different wavelengths, coupled with the fact that the energy is dissipated safely as visible light, make umbelliferone a useful sunscreen agent. The absorption changes in alkaline solution, since the phenolic hydroxyl group is deprotonated (pK_a = 7.7).

[edit] Uses

The ultraviolet activity of umbelliferone led to its use as a sunscreen agent, and an optical brightener for textiles. It has also been used as a gain medium for dye lasers. Umbelliferone can be used as a fluorescence indicator for metal ions such as copper and calcium. It acts as a pH indicator in the range 6.5-8.9.

[edit] Derivatives of umbelliferone

Umbelliferone is the parent compound for a large number of natural products. Herniarin or 7-O-methylumbelliferone (7-methoxycoumarin) occurs in the leaves of water hemp (Eupatorium ayapana) and rupturewort. O-glycosylated derivatives such as skimmin (7-O-β-D-glucopyranosylumbelliferone) occur naturally and are used for the fluorimetric determination of glycoside hydrolase enzymes. Isoprenylated derivatives are also widespread, such as marmin (found in grapefruit skin and in the bark of the Bael tree) and furocoumarins such as marmesin, angelicin and psoralen.

Herniarin and marmin, umbelliferone derivatives

[edit] See also

• Aesculetin

[edit] Notes

[edit] References

This article's citation style may be unclear. The references used may be made clearer with a different or consistent style of citation, footnoting, or external linking. (September 2007)

1. F. M. Dean Naturally Occurring Oxygen Ring Compounds, Butterworths, London, 1963.
2. J. A. Joule, K. Mills Heterocyclic Chemistry, 4th edition, Blackwell Science, Oxford, UK, 2000.
3. Comprehensive Natural Products Chemistry, Volume 2, p 677, D. H. R. Barton, K. Nakanishi, O. Meth-Cohn, editors, Elsevier, Oxford, UK, 1999.

[edit] External links

• USDA ARS info on uses