Do acetals and hemiacetals give 2,4 DNP test?
The standard mixture for a 2,4-DNP test contains 2,4-DNP and conc. Sulfuric Acid in EtOH/water here. This is sufficient to hydrolyse most acetals and hemi-acetals so they will give a positive test. Cyclic acetals such as dioxolanes are more stable and may not.