Avobenzone

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Avobenzone
Skeletal formula of avobenzone
Space-filling model of the avobenzone molecule
Names
IUPAC name
1-(4-Methoxyphenyl)-3-(4-tert-butylphenyl)propane-1,3-dione
Other names
butylmethoxydibenzoylmethane; 4-tert-butyl-4'-methoxydibenzoylmethane
Identifiers
70356-09-1 YesY
ChEMBL ChEMBL1200522 N
ChemSpider 46261 YesY
EC Number 274-581-6
Jmol 3D model Interactive image
KEGG D03015 YesY
PubChem 51040
UNII G63QQF2NOX YesY
  • InChI=1S/C20H22O3/c1-20(2,3)16-9-5-14(6-10-16)18(21)13-19(22)15-7-11-17(23-4)12-8-15/h5-12H,13H2,1-4H3 YesY
    Key: XNEFYCZVKIDDMS-UHFFFAOYSA-N YesY
  • InChI=1/C20H22O3/c1-20(2,3)16-9-5-14(6-10-16)18(21)13-19(22)15-7-11-17(23-4)12-8-15/h5-12H,13H2,1-4H3
    Key: XNEFYCZVKIDDMS-UHFFFAOYAG
  • O=C(c1ccc(cc1)C(C)(C)C)CC(=O)c2ccc(OC)cc2
Properties
C20H22O3
Molar mass 310.39 g/mol
Appearance colorless crystal
Vapor pressure {{{value}}}
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
N verify (what is YesYN ?)
Infobox references

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.[1] This enol form is stabilized by intramolecular hydrogen-bonding within the β-diketone.[2] 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 357 nm.[3]

History

Avobenzone was patented in 1973 and was approved in the EU in 1978. It was approved by the FDA in 1988. Its use is approved worldwide.

Avobenzone is sensitive to the properties of the solvent, being relatively stable in polar protic solvents and unstable in nonpolar environments. Also, when it is irradiated with UVA light, it generates a triplet excited state in the keto form which can either cause the avobenzone to degrade or it can transfer energy to biological targets and cause deleterious effects.[1]

Avobenzone has been shown to degrade significantly in light, resulting in less protection over time.[4][5][6] The UV-A light in a day of sunlight in a temperate climate is sufficient to break down most of the compound. Data presented to the Food and Drug Administration by the Cosmetic, Toiletry and Fragrance Association indicates a -36% change in avobenzone's UV absorbance following one hour of exposure to sunlight.[7] This degradation can be reduced by using a photostabilizer, like octocrylene. Other photostabilizers include:

  • 4-Methylbenzylidene camphor (USAN Enzacamene)
  • Tinosorb S (USAN Bemotrizinol, INCI Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine)
  • Tinosorb M (USAN Bisoctrizole, INCI Methylene Bis-Benzotriazolyl Tetramethylbutylphenol)
  • Butyloctyl Salicylate (Tradename HallBrite BHB - [1])
  • Hexadecyl Benzoate
  • Butyloctyl Benzoate
  • HallBrite PSF (INCI UNDECYLCRYLENE DIMETHICONE)[8]
  • Mexoryl SX (USAN Ecamsule, INCI Terephthalylidene Dicamphor Sulfonic Acid)
  • Corapan TQ (INCI Diethylhexyl 2,6-Naphthalate)[9]
  • Parsol SLX (INCI Polysilicone-15)[10]
  • Oxynex ST (INCI Diethylhexyl Syringylidene Malonate[11]
  • Polycrylene (INCI Polyester-8)[12]
  • SolaStay S1 (INCI Ethylhexyl Methoxycrylene)[13]

Complexing avobenzone with cyclodextrins may also increase its photostability.[14] Formulations of avobenzone with hydroxypropyl-beta-cyclodextrin have shown significant reduction in photo-induced degradation, as well as increased transdermal penetration of the UV absorber.[15]

According to some studies, "the most effective sunscreens contain avobenzone and titanium dioxide."[16][17] Avobenzone can degrade faster in light in combination with mineral UV absorbers like zinc oxide and titanium dioxide, though with the right coating of the mineral particles this reaction can be reduced.[18] A manganese doped titanium dioxide may be better than undoped titanium dioxide to improve avobenzone's stability.[19]

Avobenzone reacts with minerals to form colored complexes. Manufacturers of avobenzone, like DSM recommend to include a chelator to prevent this from happening. They also recommend to avoid the inclusion of iron and ferric salts, heavy metals, formaldehyde donors and PABA and PABA esters.

The makers of Coppertone advise that avobenzone binds iron and can cause staining of clothes washed in iron-rich water.

Avobenzone also reacts with boron trifluoride to form a stable crystalline complex that is highly fluorescent under UV irradiation. More interestingly, the emission color of the crystals relies on the molecular packing of the boron avobenzone complex. The photoluminescence may also be altered by mechanical force in the solid state, resulting in a phenomenon called "mechanochromic luminescence". The altered emission color recovers itself slowly at room temperature or more swiftly at higher temperatures.[20]

See also

Notes

  1. ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Free text.png Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ CTFA letter re: Tentative Final Monograph for OTC Sunscreen
  8. ↑ http://www.hallstar.com/pis.php?product=1A054
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ http://www.dsm.com/en_US/downloads/dnp/Parsol_SLX_Skin.pdf
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ http://www.hallstar.com/techdocs/Polycrylene&CorapanTQAvobenzoneStabilization.pdf
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  18. ↑ Stability Study of Avobenzone with Inorganic Sunscreens, Kobo Products Poster, 2001, Online version
  19. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  20. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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