Some phosphorothionate imported fire ant toxicants with delayed kill

Abstract

Twenty-one diethyl aryl phosphorothionates (2), (Et0)2P(=S)OC6H3XY, were prepared and tested as imported fire ant (IFA) toxicants. The substituents placed on the aryl ring include bromo esters, ketones, imines, an aldehyde, an oxime, a semicarbazone, a phenylhydrazone, a trifluoromethyl, an acylhydrazone, and a benzylidene malononitrile substituent. The phosphorothionates with both a bromo and a COzR substituent on the phenyl ring were poorer toxicants than the corresponding phosphorothionates with a single Br or C02R substituent on it. Phosphorothionates 2 [X = 4-C(=O)CH2Ph, Y = H; X = 4-C(=O)NHNH2, Y = H I were both found to give delayed kill at 0.1% toxicant in soybean oil, while 2 (X = CF3, Y = H) was found to be nearly as good an IFA toxicant. A QSAR study found the toxicity of 2 to be correlated with the steric parameter MR and to a lesser extent with II and u.