Fenthion-ethyl was produced by adapting the standard organophosphorothioate assembly used across the fenthion family. Commercial manufacture began with preparation of the phosphorothiochloridate intermediate, generated from inexpensive phosphorus trichloride and sulphur chemistry under controlled conditions. This activated phosphorus species was then reacted with the appropriate ethyl-substituted thioether alcohol to form the O-alkyl phosphorothioate framework that defines fenthion-ethyl. Producers focused on achieving clean substitution at phosphorus, managing sulphur-based impurities, and purifying the resulting ester to technical grade suitable for formulation.
