What it is
t-Butyl alcohol, with the formula (CH3)3COH, is the simplest tertiary alcohol, meaning its hydroxyl-bearing carbon has no adjacent hydrogen, which makes it resistant to oxidation. It is a colorless solid that melts near room temperature, has a camphor-like odor, and is miscible with water and many organic solvents. In product formulation it functions mainly as a solvent and as a denaturant that renders ethanol unfit to drink while preserving its usefulness.
Safety & warnings
In cosmetics t-butyl alcohol is typically present at small levels as a solvent or as a denaturant within denatured alcohol rather than as an active. People who prefer to avoid alcohol-denatured formulas may wish to note its presence, but it appears in finished sunscreens in minor, functional amounts.
Origin & sourcing
t-Butyl alcohol is a synthetic compound produced industrially. It is obtained from isobutane as a byproduct of propylene oxide manufacturing and can also be made by catalytic hydration of isobutylene. It is not derived from natural sources for cosmetic use.
Questions everyone asks
Why is t-butyl alcohol in my sunscreen?
It usually serves as a solvent or as a denaturant within denatured alcohol, helping process the formula rather than acting as an active skincare ingredient.
Is t-butyl alcohol the same as the drying alcohol in toners?
No. It is a different, tertiary alcohol used mainly as a solvent and ethanol denaturant, typically present in small functional amounts.
Is it natural?
No, it is made industrially, for example as a byproduct of propylene oxide production or by hydrating isobutylene.