Ten new aroylureas have been synthesized by the reaction of 2-amino-5-trifluoromethyl-1,3,4- thiadiazole with aroyl isocyanates. Their structures were characterized by IR, ¹H NMR spectra and elemental analysis, while the crystal structure of 2j was determined by X-ray single-crystal diffraction. The crystal of this compound belongs to triclinic system with space group P-1, and a＝0.54191(15) nm, b＝0.7766(2) nm, c＝1.7161(5) nm, α＝98.668(5)°, β＝95.103(5)°, γ＝101.070(5)°, V＝0.6955(3) nm³, Z＝2, D_c＝1.653 g/cm³, F(000)＝352, μ＝0.289 mm^－1. The preliminary biological activity tests showed that some title compounds have good activity as plant growth regulator.

Key words: aroylurea, biological activity, synthesis, crystal structure, 1,3,4-thiadiazole