What’s an isomer? “In chemistry, isomers are molecules or polyatomic ions with identical molecular formulas — that is, same number of atoms of each element — but distinct arrangements of atoms in space.” (Reference) So let’s say you have a molecule that has C18H36O2 – stearic acid. This molecule could be arranged in a few different ways. You’ve seen the version that has 18 carbon atoms in a row, but there could be a version that has 16 carbon atoms in a row with a branch of two carbon atoms or 14 carbon atoms in a row with a branch of 4 carbon atoms. These differently shaped atoms would be called isomers of the stearic acid molecule. One might be called isostearate.
Read more in this post – Chemistry: Isomers and how they relate to the isopropyl esters…