Young Chemist 1,3-Propanediol is a cosmetic chemical that is commonly used in various personal care products. It serves multiple purposes and offers several benefits for both the formulation and performance of cosmetic products. Here is a description of 1,3-Propanediol, its benefits, how to use it, and some cautions to be aware of: 1,3-Propanediol, also known as propylene glycol, is a clear, odorless liquid that belongs to the class of diols. It has a molecular formula of C3H8O2 and is soluble in water and most organic solvents. It is commonly derived from renewable sources, making it an environmentally friendly option for cosmetic formulations.