New 2-(1,3,4-oxadiazole-2-yl) benzoic acids and salts and esters thereof, as well as certain 2-(2-oxazolyl) benzoic acids, salts and esters, having the formula: ##SPC1## Where X is nitrogen or C-R" (R" being hydrogen or methyl), R is phenyl or various substituents, and R' and the Y's are hydrogen or various substituents, are effective preemergence or postemergence herbicides, on various crops. The chemicals act selectively and are useful against purple nutsedge and in cranberry. Oxadiazoles of the invention may be made by reacting a benzhydrazide with phthalic anhydride to form a hydrazide which is cyclized by removal of the elements of water, using as a catalyst fuming sulfuric acid or dimethylformamide-sulfur trioxide complex.
新的2-(
1,3,4-噁二唑-2-基)
苯甲酸及其盐和酯,以及某些2-(2-
噁唑基)
苯甲酸、盐和酯,其
化学式为:##
SPC1## 其中X是氮或C-R"(R"为氢或甲基),R是苯基或各种取代基,而R'和Y是氢或各种取代基。这些
化学物质在各种作物上具有有效的前出和后出
除草剂作用。这些
化学物质具有选择性作用,并且对紫色坚果草和蔓越莓有用。本发明的噁二唑可以通过将苯
肼与
邻苯二甲酸酐反应形成
肼,然后通过去除
水的元素使其环化,使用烟雾
硫酸或二甲基甲酰胺-
三氧化硫复合物作为催化剂。