"Controlled Amount" Limited by One-Sentence Definition in
Specification Control of the amount of protic material present
in the reaction is important. Generally, when the reaction is
conducted in aniline, water present in the reaction in an amount
greater than about 4% H2 O, (based on volume of the reaction
mixture) inhibits the reaction of the aniline with the
nitrobenzene to an extent where the reaction is no longer
significant. Reducing the amount of water to below the 4% level
causes the reaction to proceed in an acceptable manner. When
tetramethylammonium hydroxide is utilized as a base with aniline
as the solvent, as the amount of water is reduced further, e.g.,
down to about 0.5% based on the volume of the reaction mixture,
the total amount of 4-nitrodiphenylamine and
4-nitrosodiphenylamine increases with some loss in selectivity
so that more 2-nitrodiphenylamine is produced but still in minor
amounts. Thus, the present reaction could be conducted under
anhydrous conditions. A “controlled amount” of pr