| 摘要 |
A process for preparing a compound of the formula <IMAGE> wherein m represents zero or 1, which comprises reacting azobenzene with nitric acid in the presence of sulfuric acid in two steps, wherein (1) THE FIRST-STEP REACTION IS CARRIED OUT UNDER THE FOLLOWING CONDITIONS 0<X</=80, 0<Y</=11, AND -0.3X+12</=Y</=-0.22X+22 WHEREIN X IS THE REACTION TEMPERATURE IN DEG C., and y is the weight ratio of sulfuric acid to water and fed into the reaction system, and (2) THE SECOND-STEP REACTION IS CARRIED OUT UNDER THE FOLLOWING CONDITIONS 0</=X, AND -(1.7/100)X+1.7</=Y</=-(3.9/88)X+3.9.
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