The present invention concerns new 5-nitropyrimidine derivatives and their acid addition salts as well as compositions containing them and their use, for selective pre- and post-emergent combating of weeds and for diminishing the growth of lawn, cereals and suckers. The new 5-nitropyrimidines have the formula ##STR1## wherein R.sub.1 is alkyl with 2-7 carbon atoms, alkenyl or cycloalkyl; R.sub.2 is optionally substituted lower alkyl, alkoxy or alkylthio, alkenyloxy or alkenylthio, cycloalkoxy or cycloalkylthio; R.sub.3 is hydrogen, lower alkyl, haloalkyl, alkoxy, alkylthio or dialkylamino.
                            本发明涉及新的5-
硝基嘧啶衍
生物及其酸盐添加物,以及含有它们的组合物和它们的用途,用于选择性预防和后期防治杂草,以及减少草坪,谷物和萌芽的生长。新的5-
硝基嘧啶的
化学式为##STR1##其中R.sub.1是2-7碳原子的烷基,烯基或环烷基;R.sub.2是可选取取代的低碳烷基,烷氧基或烷基
硫醚,烯氧基或烯基
硫醚,环烷氧基或环烷基
硫醚;R.sub.3是氢,低碳烷基,卤代烷基,烷氧基,烷基
硫醚或双烷基
氨基。