2,3-Dimethyl-4-nitroso-1-phenyl-3-pyrazolin-5-one 3H-Pyrazol-3-one, 1,2-dihydro-1,5-dimethyl-4-nitroso-2-phenyl- 3H-Pyrazol-3-one, 1,2-dihydro-1,5-dimethyl-4-nitroso-2-phenyl- (9CI) 4-24-00-00104 (Beilstein Handbook Reference) 4-Nitrosoantipyrin 4-Nitrosoantipyrine 885-11-0 ANTIPYRINE, 4-NITROSO- BRN 0201816 CCRIS 2908 EINECS 212-941-6 NSC 163932