The reaction between acetyl chloride and sodium hydroxide is a nucleophilic substitution reaction. In this reaction, the hydroxide ion (OH-) from sodium hydroxide acts as a nucleophile and attacks the carbonyl carbon of acetyl chloride. This results in the breaking of the carbon-chlorine bond and the formation of a new carbon-oxygen bond. The products of the reaction are sodium acetate and hydrochloric acid.

The overall reaction can be represented as follows:

CH3COCl + NaOH → CH3COONa + HCl

The reaction proceeds through a nucleophilic addition-elimination mechanism. In the first step, the hydroxide ion attacks the carbonyl carbon of acetyl chloride, forming a tetrahedral intermediate. This intermediate then undergoes elimination of the chloride ion, resulting in the formation of sodium acetate.

The rate of the reaction is influenced by a number of factors, including the concentration of the reactants, the temperature, and the presence of a catalyst. The reaction is typically carried out in an aqueous solution at room temperature. A catalyst, such as pyridine or triethylamine, can be used to increase the rate of the reaction.