Here's why:

* Ferric chloride test: This test is used to detect the presence of phenols and enols. The reaction between ferric ions (Fe³⁺) and the phenolic or enolic hydroxyl group forms a colored complex, often purple or green.

* Acetoacetic ester structure: Acetoacetic ester exists in equilibrium between its keto and enol forms. However, the keto form is the dominant tautomer. The keto form does not have a free hydroxyl group capable of reacting with ferric ions.

Therefore, acetoacetic ester does not give a positive ferric chloride test.

Important Note: While acetoacetic ester itself does not give a positive ferric chloride test, its enol form is capable of reacting with ferric ions. However, the enol form is present in very low concentrations at equilibrium, making the reaction very weak and not easily observable.