(4-Nitrophenyl)phenylamine-d5 is deuterium labeled(4-Nitrophenyl)phenylamine (N504462), a useful compound to investigate the energy ofN-H-bond dissociation in phenothiazines and diphenylamines. (4-Nitrophenyl)phenylamine can also be used to determine the chemoselectivity among functional groups in Ullmann-type C-O and C-N couplings.