What it is
Octyldodecanol is a clear, slightly yellow, odorless oily liquid that serves as a very common, medium-spreading emollient. Chemically it is a branched-chain fatty alcohol (a Guerbet alcohol) with the molecular formula C20H42O. In formulas it softens and conditions the skin, helps dissolve other oily ingredients, and contributes a smooth, cushioned feel, which makes it useful across products from sun sticks and lip balms to serums.
Safety & warnings
Octyldodecanol is a large, oily branched fatty alcohol used widely as an emollient and is not the same as the short-chain drying alcohols; cosmetic references treat it as a routine skin-softening ingredient. As a rich emollient oil, those prone to congestion in heavy occlusive textures may prefer lighter formulas, but it is generally well tolerated.
Origin & sourcing
Octyldodecanol is manufactured synthetically as a Guerbet alcohol. The Guerbet reaction converts a primary fatty alcohol into a larger branched dimer alcohol with loss of water, using alkali catalysts at high temperature; such branched-chain Guerbet alcohols are of commercial interest as components of cosmetics.
History
The chemistry behind it, the Guerbet reaction, is named after the French chemist Marcel Guerbet (1861–1938), who described the conversion of primary alcohols into their branched dimer alcohols.
Questions everyone asks
Is octyldodecanol a drying alcohol?
No. It is a large, oily fatty alcohol used as an emollient to soften skin, not a volatile drying alcohol like ethanol.
What does octyldodecanol do in sunscreen?
It acts as an emollient and solvent, helping the product spread smoothly, dissolve oily ingredients, and leave a soft skin feel.
Is it natural or synthetic?
It is made synthetically as a Guerbet alcohol, a branched fatty alcohol produced from primary fatty alcohols.