Preparation of picramic acid
10 g of picric acid and 10 g of 35 % sodium hydroxide are dissolved in 600 ml water. After heating up to 55° C the liquid is stirred vigorously and a solution of 40 g crystallized sodium sulfide (Na2S · 9H2O) and 100 ml water is dropwise added during 10 minutes. After the addition, 127.5 g of powdered picric acid are scattered in, about a teaspoonful at a time, a solution of 220 g sodium sulfide in 400 ml water being allowed to run in simultaneously during 10 minutes. The addition of the picric acid should end just at the same time as that of the sodium sulfide. If the temperature exceed 65° C a little ice must be added. After all has been added, stirring is continued for a further 10 minutes, after which 400 g of ice are added quickly, whereupon the sodium salt of the picramic acid is completely precipitated at once. After standing 10 hours it is filtered off and washed with 10% brine. The free picramic acid is obtained by stirring up the sodium salt with 500 ml of water, warming to 80° C, and acidifying with dilute sulfuric acid. After cooling and standing for 10 hours the picramic acid is filtered off, the yield being about 100 g.
By slightly modified method picramic acid is prepared by dissolving 137.5 g of picric acid in 1200 ml water containing 36 g sodium carbonate at 50° C. When the carbon dioxide has been driven off, 240 g crystallized, sodium sulfide (Na2S · 9H2O) dissolved in 450 ml water is dropwise added during half an hour with good stirring. At the same time a mixture of 108 g 30 % hydrochloric acid, and 300 ml water added so that the hydrochloric acid takes about a minute longer than the sodium sulfide. After all has been added, stirring is continued for half an hour without heating, the mixture allowed to stand for 12 hours and filtered. The precipitate is washed with 100 ml saturated brine. The crude sodium picramate is dissolved in 2 litres water, and the filtered solution poured into a dilute hydrochloric acid prepared from 70 ml of 30 % hydrochloric acid and 400 ml water at 90° C. The pure picramic acid is completely precipitated within 24 hours; it is then filtered off and washed with a little water, after which it is pressed and dried at 80° C, the yield being about 100 g or 83%.
The fundamental processes of dye chemistry, by F. David, 77-78, 1921
2-amino-4,6-dinitrophenol, picramic acid, picramic acid, monosodium salt, picramic acid, sodium salt
2-Amino-4,6-dinitrophenol, Picramic acid, 96-91-3, 6-Amino-2,4-dinitrophenol, Fourrine 4R, Fourrine 93, Furro 4R, Oxidation Base 21, Zoba 4R, Acide picramique, Phenol, 2-amino-4,6-dinitro-, C.I. Oxidation Base 21, 2,4-Dinitro-6-aminophenol, 4,6-DINITRO-2-AMINOPHENOL, CI Oxidation Base 21, NSC 36939, Acide picramique [French], UNII-5VDQ7GK8L3, 1-Amino-2-hydroxy-3,5-dinitrobenzene, 2-amino-4,6-dinitro-phenol, CCRIS 1003, HSDB 4319, QXYMVUZOGFVPGH-UHFFFAOYSA-N, EINECS 202-544-6, UN3317, BRN 0989416, CI 76540, AI3-08922, Picramicacid, AC1NKYV1, DSSTox_CID_4479, 5VDQ7GK8L3, DSSTox_RID_77418, DSSTox_GSID_24479, SCHEMBL18124, 4,6-dinitro-2-amino-phenol, Ex073, 2-azanyl-4,6-dinitro-phenol, CHEMBL3183248, NSC4861, MolPort-000-794-302, BB_SC-1516, AC1Q5164, ACT07496, NSC-4861, NSC36939, ZINC1316284, Tox21_202887, 2-AMINO-4,6-DINITRO PHENOL, BBL028138, NSC-36939, SBB058601, STK711606, AKOS000120580, LS-2014, MCULE-4569162230, NE11171, VZ23602, CAS-96-91-3, NCGC00260433-01, AC-11460, AJ-25373, AK-36994, AN-42818, KB-73795, OR003948, OR381453, DB-020415, ST4032788, D0813, 4-13-00-00909 (Beilstein Handbook Reference), A845654, AE-641/00206029, I01-7104, 3B3-005348, T0519-7931, A1547/0067316, 2-Amino-4,6-Dinitrophenol, wetted with not <20% water by mass, 2-Amino-4,6-Dinitrophenol, wetted with not <20% water by mass [UN3317] [Flammable solid], 2-Amino-4,6-Dinitrophenol, wetted with not <20% water by mass [UN3317] [Flammable solid]