Sharnin, G. P. published the artcileIonization constants of nitro-substituted diphenylamine in dimethylformamide, Synthetic Route of 1821-27-8, the publication is Zhurnal Obshchei Khimii (1973), 43(7), 1564-9, database is CAplus.
Ionization constants were determined for 19 polynitro derivatives of Ph2NH and substituted Ph2NH in DMF and in aqueous sulfolane. The acidity of these amines increased with the number of NO2 groups present, o-NO2 groups having an especially large effect. In 2,4,2′-trinitro-4-R-substituted compounds, a correlation was observed between pKa and δ- of the R groups. The pKa’s of these compounds in DMF were lower than those in aqueous sulfolane.
Zhurnal Obshchei Khimii published new progress about 1821-27-8. 1821-27-8 belongs to catalysis-chemistry, auxiliary class Nitro Compound,Amine,Benzene, name is Bis(4-nitrophenyl)amine, and the molecular formula is C3H6O2, Synthetic Route of 1821-27-8.
Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia