Mechanisms of isomerization and hydration reactions of typical β-diketone at the air-droplet interface

•A good accumulation and accommodation of interface is towards acetylacetone (AcAc).•AcAc isomerization is favorable on acidic interface as “water-bridge” is destroyed.•Carbonyl/hydroxyl O-atom of AcAc displays an energetical preference to hydration.•Unfeasible hydration on acidic interface leads to the accumulation of product.