| Abstract: | Data are presented on changes in physical properties and insecticidal activity resulting from modifications in chemical structure in two groups of compounds. The first group consists of propoxur and three closely related N-methylcarbamates and the corresponding N-acetyl compounds The parent compounds are all highly toxic to adult mosquitos by topical application in solution and deposits from water-dispersible powder formulations on plywood and plaster of Paris panels have long residual activity. N-acetylation is not accompanied by excessive loss of toxicity to mosquitos, but increases volatility to the extent that none of the four N-acetyl derivatives can be considered as potential residual insecticides. The second group consists of tetrachlorvinphos and related vinyl phosphates and vinyl phosphorothionates which show a wide range of toxicity both to adult mosquitos and to mammals. |
