Phosdiphen is used specifically for the control of rice blast diseases
(Pyricularia oryzae).
ChEBI: Phosdiphen is a dichlorobenzene.
Phosdiphen was produced through a phosphorus chloride–based condensation route typical of mid 20th century dialkyl phosphonate chemistry. Industrial synthesis generally began with the preparation of a dichlorophosphoryl intermediate, often derived from phosphorus oxychloride, which was then reacted with appropriate phenyl and alkyl alcohol components under controlled, anhydrous conditions to form the mixed phosphonate ester. Manufacturers used acid scavengers and inert solvents to maintain selectivity and suppress hydrolysis, followed by neutralization and vacuum stripping to remove residual chlorides. The resulting technical grade material was purified by distillation or crystallisation before formulation.
Acetylcholinesterase (AchE) inhibitor.
Limited information is available in the open literature to describe the
degradation and metabolic fate of phosdiphen. Information presented
in this summary is abstracted from an unpublished report provided by
Mitsui Chemical Industry, 1979). Hydrolytic cleavage of the P-O ester
linkages is the primary degradation pathway of phosdiphen in soil, plants
and animals (Scheme 1). The cleavage product, dichlorophenol, was
recovered as both free and conjugated metabolites.
Phosdiphen (1) is stable in acidic solution and hydrolysed under alkaline
conditions at 25 °C with DT50 values of 4 days (pH 9) to 7 days (pH 7)
(PM). Phosdiphen labelled in both rings degraded rapidly in rice paddy
water with DT50 values of 1-3 days. 2,4-Dichlorophenol(2) was the major
product detected.
