AWK-I would think that acetyl chloride is more reactive with water than is acetic anhydride, with both hydrolyzing to acetic acid. Is it your experience that the reaction with amines and acetyl chloride is so fast that water can be present in the reaction medium?
(Thank the forum moderators for the modify button)
Let me take that back and rephrase the question, since the Schotten-Baumann reaction obviously works. In view of the reactivity of acyl halides, why doesn't the halide undergo significant hydrolysis under these conditions? Standard texts list acid halides as the most reactive acid derivatives toward reactions with nucleophiles.