4-Aminodiphenylamine Explained

4-Aminodiphenylamine is a diphenylamine with an additional amine substituent. This dimer of aniline has various industrial uses, including as a hair dye ingredient, but also has raised concerns about toxicity by skin contact.^[1] It is also a starting material for the synthesis of 6PPD, an antiozonant for various rubber products. A colorimetric test for the quantitative analysis of nitrite, at levels below 100 nanograms per milliliter, is based on nitrite-catalyzed coupling of 4-aminodiphenylamine with N,N-dimethylaniline.^[2]

The most common route of industrial production is by the reaction of aniline with 4‑nitrochlorobenzene followed by reduction of the intermediate 4‑nitrodiphenylamine.^[3] An alternative is the direct condensation reaction of nitrobenzene with aniline via a nucleophilic aromatic substitution of hydrogen,^[4] this again requires a reduction step.

Notes and References

1. Studies on the skin uptake and efflux kinetics of N-phenyl-p-phenylenediamine: an aromatic amine intermediate . S. K. . Khanna . Pushpa . Tewari . Anil . Joshi . G. B. . Singh . International Journal of Cosmetic Science . 9 . 3 . 1987 . 137–147 . 19456976 . 10.1111/j.1467-2494.1987.tb00470.x . 205555627 .
2. Sensitive flow injection colorimetry of nitrite by catalytic coupling of N-phenyl-p-phenylenediamine with N,N-dimethylaniline . Ryoichi . Kadowaki . Shigenori . Nakano . Takuji . Kawashima . Talanta . 1999 . 48 . 1 . 103–107 . 18967448 . 10.1016/s0039-9140(98)00227-6 .
3. Bochkarev . V.V. . Soroka . L.S. . Bashkin . J.K. . Resource-efficient technology to produce 4-aminodiphenylamine . Resource-Efficient Technologies . December 2016 . 2 . 4 . 215–224 . 10.1016/j.reffit.2016.10.011. free .
4. Stern . Michael K. . Hileman . Fredrick D. . Bashkin . James K. . The direct coupling of aniline and nitrobenzene: a new example of nucleophilic aromatic substitution for hydrogen . Journal of the American Chemical Society . November 1992 . 114 . 23 . 9237–9238 . 10.1021/ja00049a095.