Butyl Methoxydibenzoylmethane Avobenzone is an organic compound produced by the esterification of salicylic acid with butyl alcohol in the presence of an acid catalyst to produce butyl salicylate which, in a Claisen condensation reaction with benzoyl chloride or its derivatives, forms butyl methoxydibenzoylmethane. Subsequently, this product is purified using various techniques such as recrystallisation, solvent extraction and filtration to obtain the purest possible form of butyl methoxydibenzoylmethane.

Butyl Methoxydibenzoylmethane and Avobenzone are the same chemical compound.

The name defines the structure of the molecule:

• Butyl refers to the butyl group (C₄H₉), a four-carbon alkyl group.
• Methoxy refers to the methoxy group (CH₃O), a functional group consisting of a methyl group bonded to an oxygen atom.
• Dibenzoylmethane refers to the central structure of the molecule, which consists of a methane group (CH₂) bonded to two benzoyl groups (C₆H₅C=O).

The synthesis of Butyl Methoxybenzoylmethane (Avobenzone) typically involves the following steps:

• Condensation of methyl anthranilate and 4-tert-butylbenzoyl chloride. Methyl anthranilate reacts with 4-tert-butylbenzoyl chloride in the presence of a base such as triethylamine to form an intermediate product.
• Reaction with methoxyacetyl chloride. The intermediate product is reacted with methoxyacetyl chloride to form avobenzone.

It appears as a white powder that is not very soluble in water, but soluble in organic solvents such as isopropyl alcohol, ethanol and oils.

What it is used for and where

Cosmetics

It is a restricted ingredient  VI/8   as a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Ingredient or substance at  risk: 1-(4-tert-Butylphenyl)-3-(4-methoxyphenyl) propane-1,3-dione / Avobenzone

Butyl Methoxydibenzoylmethane is generally used in cosmetics as a UV filter, maximum absorption length of 360nm (1) and as an INCI ingredient has the following functions:

• UV filter. It is the defining ingredient in sun creams that can mitigate the sun's ultraviolet (UV) radiation, which is a high risk factor for the development of skin cancer, erythema and photo-ageing. 
• UV absorber. It acts by intercepting ultraviolet light before it can cause damage by reducing its energy through dissipation and returning it to a lower energy state.
• Light stabilizer. It prevents light from degrading light-sensitive components and slows down degradation reactions that have already begun. The mechanism is, in a way, similar to antioxidants and the effectiveness depends on the.complexity of the formulation and the density of the product.

The most relevant studies on this chemical compound have been selected with a summary of their contents:

Butyl Methoxydibenzoylmethane studies

• Molecular Formula: C₂₀H₂₂O₃
• Molecular Weight: 310.393 g/mol
• UNII: G63QQF2NOX
• CAS: 70356-09-1 87075-14-7  185160-18-3  112725-59-4
• EC Number: 274-581-6
• PubChem Substance ID 329751311
• MDL number MFCD00210252

Synonyms:

• Avobenzone
• Parsol 1789
• Butyl methoxydibenzoylmethane
• 1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)propane-1,3-dione
• 4-tert-Butyl-4'-methoxy-dibenzoylmethane
• Escalol 517
• Eusolex 9020
• 1-(4-(tert-Butyl)phenyl)-3-(4-methoxyphenyl)propane-1,3-dione
• 1-(p-tert-Butylphenyl)-3-(p-methoxyphenyl)-1,3-propanedione
• 1-(4-tert-Butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione
• HSDB 7423
• 1,3-Propanedione, 1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)-
• 1-(4-(1,1-Dimethylethyl)phenyl)-3-(4-methoxyphenyl)-1,3-propanedione
• 1-(4-Methoxyphenyl)-3-(4-tert-butylphenyl)-1,3-propanedione
• 1,3-Propanedione, 1-(4-(1,1-dimethylethyl)phenyl)-3-(4-methoxyphenyl)-
• 1-(4-(1,1-Dimethylethyl)phenyl)-3-(4-methoxyphenyl)-1,3-propanedi- one
• 1-(4-(1,1-Dimethylethyl)phenyl)-3-(4-methoxyphenyl)propane-1,3-dione
• 1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)-1,3-propanedione
• 4-t-butyl-4'-methoxy-dibenzoylmethane

References____________________________________________

(1) Li X, Hu J, Chen L, Zhang W. The adsorption behaviour and photoprotection effect of UV filter absorbed on the surface of human hair.  Int J Cosmet Sci. 2016 Feb;38(1):52-9. doi: 10.1111/ics.12247.