4-硝基水杨酸

2,2'-dihydroxy-4,4'-hydrazo-di-benzoic acid

2,2'-dihydroxy-4,4'-azo-di-benzoic acid dimethyl ester

2-羟基-4-(羟基氨基)苯甲酸

2,2'-dihydroxy-4,4'-azoxy-di-benzoic acid