Synthesis and herbicidal activity of some new pyrazolyl amido urea derivatives

A new series of amido ureas were synthesized from the 3-ethyl-1-methyl-5-hydrazinocarbonylpyrazole and substituted phenyl isocyanate.Their structures were confirmed by 1H NMR,FTIR,MS and elemental analysis.The herbicidal activity of these compounds was evaluated.The results showed that most of them exhibited higher herbicidal activity against dicotyledonous weeds than that of monocotyledonous weeds.For example,compound 3i had 100% inhibitory effect against Abutilon theophrasti and Amaranthus retroflexus at 2 250 g/ha in post-emergence and pre-emergence condition.Compound 3i had also moderate inhibitory effect against dicotyledonous weeds at the dose of 375 g/ha.