“…In such compounds, which show generally favourable mammalian toxicity, the nature of the aryl substituents is frequently less critical than for corresponding 0,O-diethyl phosphates (Drabek and Fluck 1979), and they tend also to be effective against OP-resistant strains of insects (Drabek and Fluck 1979, Hirashama et al 1984, Kimura et al 1984. For example, prothiophos oxon (9) and its S-methyl, S-ethyl and S-n-butyl analogues were poor inhibitors of AChE, but (9) and its S-n-butyl homologue were highly insecticidal, especially towards OPresistant houseflies (Kimura et al 1984). T h e S-propyl and S-n-butyl, although not the S-methyl and S-ethyl oxons, were converted into more potent inhibitors by ratliver microsomes ( + NADPH); sulphoxides of the first two oxons are better leaving groups for interaction with AChE than 2,4-dichlorophenol, whereas those arising from the smaller alkvlthio groups appear to be deactivated by rapid hydrolysis.…”