The chlorine atom in acyl chlorine has the electron-absorbing effect, enhances the affinity of carbon, makes acyl chlorine more susceptible to the attack of Nucleophilic reagent, and Cl− is also a good leaving group, so the activity of nucleophilic acyl substitution reaction is the strongest in all carboxylic acid derivatives.
The simplest example of this is the hydrolysis of lower-level acyl chlorine in the case of water:
RCOCL + H-oh→rcooh + HCl In addition, the acyl chlorine can also react with ammonia/amine to produce amide (ammonia solution), reacts with alcohols to produce esters (alcohols), reacts with carboxylic ions to produce anhydride, etc. Alkali (such as sodium hydroxide, pyridine, or amine) is generally added to the reaction to catalyze the reaction and to absorb the by-product hydrogen chloride. As the acyl chlorine is more active than the corresponding carboxylic acid, the reaction of using acyl chlorine as raw material is often higher, so the amide, ester and anhydride are often made of acyl chlorine instead of carboxylic acid.