Avobenzone (trade names Parsol 1789, Milestab 1789, Eusolex 9020, Escalol 517, Neo Heliopan 357 and others, INCI Butyl Methoxydibenzoylmethane) is an oil-soluble ingredient used in sunscreen products to absorb the full spectrum of UVA rays. It is a dibenzoylmethane derivative. Avobenzone exists in the ground state as a mixture of the enol and keto forms, favoring the chelated enol. This enol form is stabilized by intramolecular hydrogen-bonding within the β-diketone. Its ability to absorb ultraviolet light over a wider range of wavelengths than many other sunscreen agents has led to its use in many commercial preparations marketed as "broad spectrum" sunscreens. Avobenzone has an absorption maximum of 357nm.

Chemical Name	1-(4-tert-Butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione
Synonyms	Avobenzone;
CAS No.	70356-09-1
Molecular Formula	C20H22O3
Molecular Weight	310.38700
PSA	43.37000
LogP	4.44840

Appearance & Physical State	white powder
Density	1.079
Boiling Point	463.6ºC at 760 mmHg
Melting Point	81-84ºC
Refractive Index	1.546
Storage Condition	Keep container tightly closed. Protect from light.

Safety Statements	S60-S61
HS Code	29145000
RIDADR	UN3077 9/PG 3
Risk Statements	R50/53
Hazard Codes	N