The raw materials are acetyl chloride and aniline. The specific mechanism is that firstly, lone pair N on aniline attacks carbonyl C of acetyl chloride, and then the double bond between carbon and oxygen opens, and O shows electronegativity with a pair of electrons, and an H on N undergoes hydrogen transfer to oxygen. Then a pair of negative electrons on O attack C to change back to double bond, which breaks the chlorine-carbon bond of acetyl chloride, and chlorine leaves in the form of negative ions. Finally, H+ on samarium salt is removed to generate acetanilide.