设计合成了一系列文献中未报道的2-取代-6-甲基-4-苯基-3（2H）-哒嗪酮类化合物，其结构经过¹H NMR和元素分析确证，化合物4e进行了X 射线衍射晶体结构分析. 利用油菜平皿法和稗草小杯法对化合物进行了生物活性的测定. 初步生物活性测试结果表明，化合物4具有较好的除草活性. 定量构效关系表明，化合物4结构中哒嗪环2-位取代基的变化，影响了化合物的抑制活性. 当作用对象为油菜时，化合物的活性可能主要与取代基R的立体参数B4和疏水性有关；当作用对象为稗草时，化合物的活性可能主要与取代基R的疏水性有关. 部分化合物4的抑制活性与对照药品5b，5k基本相当，但没有表现出5b，5k所具有的白化效果. 化合物4与5这两类结构类似的化合物很可能在生物体内拥有不同的作用机制.

A series of novel 2-substituted-6-methyl-4-phenyl-3(2H)-pyridazinone derivatives were synthesized. All target compounds were structurally confirmed by ¹H NMR and elemental analysis. An X-ray crystallographic structure determination was carried out in compound 4e. Herbicidal activities were evaluated through Brassica napus and Echinochloa crusgalli (L.) Beauv tests. Bioassay results showed that most of compounds exhibited better herbicidal activities. Quantitative structure-activity relationship studies showed that when the test grass was rape, their herbicidal activity was mainly related with substituent's sterimol parameter B4 and hydrophobic parameter π; when the test grass was barnyard grass, their herbicidal activity was mainly related with the hydrophobic parameter π of the substituents at the 2-position of pyridazinone ring. Some compounds 4 showed inhibitive activity equal to 5b and 5k, but showed no bleaching activity. The action mode in plants may be different in compounds 4 and 5.