AbstractThe synthesis of14C‐labelled crotamiton, which is a fungicide, an insecticide as well as a scabicide is described. Starting from 2‐bromonitrobenzene and Cu14CN,o‐toluidine, labelled with14C at the methyl group was prepared by the following sequence of reactions: NO2‐C6H4‐Br → NO2‐C6H4‐14CN → NO2‐C6H4‐14COOH → NO2‐C6H4‐14CH2OH → NO2‐C6H4‐14CH2Br → NH2‐C6H4‐14CH3. Labelledo‐toluidine was then heated with crotonic anhydride to give crotonic acido‐toluidide which was then ethylated by treatment with sodium hydride and