Twelve novel α-(2,4-dichlorophenoxyacetoxy)arylmethylphosphonates were synthesized from the intermediate (α-hydroxyl)-α-arylmethylphosphonates and 2,4-dichlorophenoxyacetyl chloride. All com-pounds synthesized were identified by 1H NMR, IR and MS techniques. The crystal structure of the com-pound 4a was determined by X-ray single-crystal diffraction. Preliminary bioassay results showed that some of these compounds had better inhibiting effect against the roots of rape and barnyard grass. Inhibitory rates of compounds 4a～4l against the roots of rape and barnyard grass were more than 90% at a dosage of 100 and 10 mg/L respectively.

Key words: crystal structure, synthesis, bioactivity, arylmethylphosphonate