Cotton herbicide SIOC0426( 4-bromo-N-( 2-chloro-6-( 4,6-dimethoxypyrimidin-2-yloxy)benzyl) aniline) was synthesized in kilo-scale from 2-chloro-6-fluorobenzaldehyde via hydrolysis,condensation,reduction and nucleophilic substitution reactions. The purity of the herbicide was determined by HPLC external standard method,and the impurities of the herbicide were elucidated by HPLC-DAD-MS. The four-step yield is above 80%,and the purity of the final product is greater than98%. The impurities are unreacted interm...