Propose a mechanism to show how acetophenone undergoes base-promoted chlorination to give trichloroacetophenone.

Acetophenone is an aromatic ketone with a phenyl group attached to a carbonyl (C=O) functional group. The presence of the carbonyl makes the molecule susceptible to nucleophilic attack, particularly at the alpha position. Understanding the structure helps in predicting how it will react under various conditions, including chlorination.

Base-promoted chlorination involves the deprotonation of the alpha hydrogen of acetophenone by a base, forming an enolate ion. This enolate ion acts as a nucleophile, attacking chlorine molecules (Cl2) to form chlorinated products. The mechanism typically proceeds through a series of steps, including the formation of the enolate, electrophilic attack, and subsequent protonation.

Electrophilic aromatic substitution (EAS) is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. In the case of acetophenone, the chlorination occurs at the aromatic ring, facilitated by the electron-withdrawing nature of the carbonyl group, which enhances the reactivity of the ring towards electrophiles like chlorine.