A process for the preparation of a compound of general formula I: ##STR1## wherein: R.sup.1 is hydrogen or C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl or C.sub.2 -C.sub.6 alkynyl, any of which may optionally be substituted with one or more substituents selected from halogen and OH; or COOR.sup.4, COR.sup.6, CONR.sup.4 R.sup.5 or CONHSO.sub.2 R.sup.4 ; R.sup.4 and R.sup.5 are each independently hydrogen or C.sub.1 -C.sub.4 alkyl optionally substituted with one or more halogen atoms; R.sup.6 is a halogen atom or a group R.sup.4 ; R.sup.2 is hydrogen or halo; R.sup.3 is C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 alkenyl or C.sub.2 -C.sub.4 alkynyl, any of which may optionally be substituted with one or more halogen atoms; or halo; the process comprising reacting a compound of general formula II: ##STR2## wherein R.sup.1, R.sup.2 and R.sup.3 are as defined for general formula I; with a nitrating agent comprising nitric acid or a mixture of nitric and sulphuric acids in the presence of an organic solvent and in the presence of acetic anhydride, characterized in that the molar ratio of acetic anhydride to compound of general formula II is from about 1:1 to 3:1.
一种制备一般式I化合物的方法:其中:R1是氢或C1-C6烷基,C2-C6烯基或C2-C6炔基,其中任何一种可以选择性地被取代为一个或多个取代基,所述取代基选择自卤素和OH; 或COOR4,COR6,CONR4R5或CONHSO2R4; R4和R5各自独立地是氢或C1-C4烷基,可选择性地取代为一个或多个卤素原子; R6是卤素原子或R4基团; R2是氢或卤素; R3是C1-C4烷基,C2-C4烯基或C2-C4炔基,其中任何一种可以选择性地被取代为一个或多个卤素原子; 或卤素; 该过程包括在有机溶剂和
乙酸酐存在下,将一般式II化合物:其中R1,R2和R3如一般式I所定义;与一种含
硝酸或
硝酸和
硫酸混合物的硝化剂反应,其特征在于
乙酸酐与一般式II化合物的摩尔比为约1:1至3:1。