Sixteen novel 5,7-dimethyl-1,2,4-triazolo[1,5-a] pyrimidine-2 thioacetohydrazone derivatives have been designed and synthesized based on the starting material 2-mercapto-5,7-dimethyl-1,2,4-triazolo [1,5-a]pyrimidine. All compounds synthesized are identified by 1^H NMR, MS and elemental analyses. Cis/trans isomers of the compounds are observed in solutions by analyzing the NMR spectroscopy and the chemical shifits of the cis/trans isomers are assigned by molecular mechanics method. Preliminary bioassay indicates that all the compounds display herbicidal activity to some extent and excellent fungicidal activity against rhizoctonia solani.

Key words: PYRRODIAZOLE P, PYRIMIDINE P, HYDRAZONE P, BIOLOGICAL ACTIVITY, PROTON MAGNETIC RESONANCE SPECTROMETRY, MASS SPECTROGRAPHY, CHEMICAL SHIFT, PESTICIDES