Synthesis and molluscicidal structure-activity relationships of some novel 1,2,4-triazole N-methyl carbamates

A new series of 1,2,4-triazole derivatives and their corresponding carbamates have been synthesized and screened for their molluscicidal activity against two types of terrestrial snail, Helix aspersa and Theba pisana, by two methods of application, either as contact or as bran baits. Several of the tested compounds exhibited good molluscicidal activity, and T pisana was more sensitive than H aspersa. Substitution at the o- and/or p-positions of the phenyl ring with chlorine or bromine gave higher molluscicidal activity than the unsubstituted compound, with o,p-dichloro substitution being optimum. In addition, compounds containing two triazole moieties showed higher molluscicidal activity, particularly as stomach poisons, than the contact toxic effect of the corresponding compound with one triazole ring. In general, carbamate derivatives were more active than their corresponding 1,2,4-triazole derivatives.