Monosulfuron was identified by m.p., IR, NMR, MS, UV and HPLC/MS analysis in this study, the results indicate that, the active ingredient of monosulfuron was N-[2′-（4′-methyl） pyrimidyl]-2-nitrobenzensulfonylurea, it′s main impurities were 2-amino-4-methylpryrimidine, 2-nitrobenzensulfonamide and ethyl 2-nitrobenzensulfonyl carbamate. The method of reverse HPLC analysis for active ingredient and main impurities in monosulfuron were established by using 250 mm× 4.6 mm stainless column of ODS 5 μm with V（CH3OH）∶V（H2O）= 60∶40 containing H3PO4 （ pH 3.0） as a mobile phase, \{0.8\} mL/min of flow rate, 225 nm as UV determination wave length. All components of monosulfuron which consisted of more than 0.1% were quantitated.
The title compound, N-（4-methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl）-N＇-（2-tritluoromethyl-phenyl）-guanidine, was synthesized and its structure was confirmed by using IR, MS,^1H NMR, and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test showed that the synthesized compound has a weak herbicidal activity.
Diamidine （A） was identified in our in vitro bio-assay as a possible inhibitor of ketol-acid reductoisomerase （KARI） from the ACD database search based on the known three-dimensional crystal structure of KARI. An investigation on interaction of A on KARI active sites, led to the design and synthesis of 15 novel monoamidines. Some of those showed better biological activity than A on rice KARI （in vitro） and in greenhouse herbicidal tests （in vivo）. The structure-biological activity relationship was investigated, which provides valuable information to further study of potential KARI inhibitors.
Bao Lei Wang Yong Hong Li Jian Guo Wang Yi Ma Zheng Ming Li
