Avobenzone (Butyl Methoxydibenzoylmethane) CAS 70356-09-1

Avobenzone (Butyl Methoxydibenzoylmethane) – Broad-Spectrum UVA Filter for Sunscreen Formulations

Basic Information

• CAS Number: 70356-09-1

• Molecular Formula: C₂₀H₂₂O₃

• Molecular Weight: 310.39 g/mol

• Synonyms: Avobenzone, Parsol 1789, Butyl Methoxydibenzoylmethane

• Appearance: Yellowish to off-white crystalline powder

• Melting Point: 81–86°C

• Solubility: Very slightly soluble in water; soluble in ethanol, propylene glycol, and oils

• Storage: Store in tightly sealed containers at 15–25°C, protected from light and moisture

Overview
Avobenzone (also known as Parsol 1789) is one of the most effective organic UVA filters available for cosmetic and sunscreen applications. It provides broad protection against long-wave UVA rays (UVA1, 340–400 nm), which are responsible for deep skin photoaging, loss of elasticity, and hyperpigmentation. However, avobenzone is photolabile and tends to degrade upon exposure to sunlight unless properly stabilized. To maintain its efficacy, it is typically combined with photostabilizers such as octocrylene, diethylhexyl 2,6-naphthalate, or antioxidants like tocopherol and chelating agents.

Mechanism of Action
Avobenzone absorbs UVA radiation through its conjugated dibenzoylmethane structure, dissipating the energy as heat. Unlike UVB filters, it penetrates deeper into the epidermis and dermis, providing critical protection against photoaging and DNA damage. Its photodegradation products may reduce efficacy, hence the need for stabilization in formulations.

Applications

• Sunscreens: Used as the primary UVA filter in broad-spectrum sunscreens, day creams, and moisturizers with SPF.

• Anti-aging products: Incorporated into formulations aimed at preventing wrinkles, fine lines, and pigmentation caused by UVA exposure.

• Daily protection: Widely used in everyday skin care products to provide continuous defense against UVA radiation.

• Combination formulations: Often combined with UVB filters (octocrylene, octinoxate, oxybenzone) for complete UV protection.

Key Benefits

• Effective UVA1 protection – prevents deep skin damage.

• Reduces photoaging, wrinkles, and hyperpigmentation.

• Compatible with various cosmetic oils and organic solvents.

• Available in a range of formulation types (creams, lotions, sprays).

• Stabilized formulations offer extended protection.

Stabilization Strategies

• Octocrylene: Stabilizes avobenzone by quenching its excited state, reducing photodegradation.

• Antioxidants: Tocopherol (vitamin E) and ascorbic acid (vitamin C) help prevent oxidation.

• Chelating agents: EDTA and other chelators minimize metal-catalyzed degradation.

• Combination with other filters: Diethylhexyl 2,6-naphthalate and other stabilizers enhance photostability.

Safety and Handling

• Generally recognized as safe at concentrations up to 3% (EU) or 5% (US).

• May cause mild skin irritation in sensitive individuals; patch testing recommended.

• Store in a cool, dry place, away from direct sunlight and moisture.

• Use appropriate personal protective equipment (gloves, safety goggles) when handling.

• Shelf life: typically 24 months under recommended storage conditions.

Quality Assurance
Each batch is tested for purity (by HPLC), melting point, and UV absorption characteristics to ensure consistent performance.