This document is applicable to the low-boiling mixed liquid with valeric acid as the main component obtained from the top of the light removal tower during the oxidation and distillation of n-valeraldehyde as raw material to produce valeric acid, which is used as raw material for the production of mixed esters. Molecular formula of valeric acid: C5H10O2 Relative molecular mass of valeric acid: 102.13 (according to the 2016 international relative atomic mass)