2,2'-5',2''-TERTHIOPHENE AND HETEROARENE ANALOGS AS POTENTIAL NOVEL PESTICIDES

Derivatives and heteroarene analogs of alpha-T were synthesized and evaluated for their pesticidal activities. Studies on physical properties, photostability, and electronic calculations were also performed on selected analogs. In the nematicide water screen under sun light, some of these compounds were found to be very fast acting and were much more potent than oxamyl and parathion (EC50 = < 0.01 ppm at 2 hours). At 1 lb/acre postemergence application 5-chloro-5"-methyloximino-alpha-T was significantly more active than alpha-T and completely controlled johnson grass, yellow foxtail, and morning-glory. However, selected analogs of alpha-T were found to have poor photostability, with half-life time ranging from 0.7 to 22 hours in thin film photostability studies under solar simulator. Electronic calculations were performed to study the effect of substitution on the ring conformation and the lowest triplet state energy. The calculation results were consistent with the lowest triplet state energy transfer mechanism for singlet oxygen formation.