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With hydrogen;palladium 10% on activated carbon; In methanol; for 6.0h;
To a solution of 4,6-dimethyl-2-nitroaniline (312 mg) in 5 mL MeOH, was added 10% Pd/C (50 mg). The mixture evacuated and flushed with H2 (3×), then was stirred under an atmosphere of H2 for 6 h. Conc. HCl (2 drops) was added and the mixture was stirred under H2 for an additional 18 h, then was filtered and concentrated to afford 280 mg of Intermediate 179.1, which was used without further purification.
With hydrogen;palladium 10% on activated carbon; In ethanol; under 760.051 Torr; for 3.0h;
A mixture of 4,6-dimethyl-2-nitroaniline (10.0 g, 60.2 mmol) and 10% Pd/C (1.0 g) in EtOH (300 niL) was stirred under an atmosphere of hydrogen (ca. 1 atm) for 3 h, then filtered through a Celite pad and concentrated in vacuo. The crude solid was dissolved in CH3CN (200 mL) and triphosgene (15.0 g, 50.5 mmol) was added. The mixture was stirred for 1 h, then H2O (200 mL) was added slowly and stirring was continued for 1 h. The precipitate was isolated by filtration and dried to give the title compound. MS: mlz = 163 (M + 1).
1,2-Diamino-4,6-dimethylbenzene. A mixture of 4,6-dimethyl-2-nitroaniline (1.66 g, 10.0 mmole) and 10% Pd/C (200 mg) in ethanol (35 mL) was hydrogenated for 2 h at room temperature under 25 psi H2. The catalyst was removed by filtration with celite and the solvent was removed by rota-evaporation to give 1.300 g (96%) of 1,2-diamino-4,5-dimethylbenzene as a brown solid. 1 H NMR (CDCl3): 6.449 (s, 1H), 6.469 (s, 1H), 3.327 (br, 2H), 3.259 (br, 2H), 2.190 (s, 3H), 2.159 (s, 3H).
EXAMPLE 3a Preparation of the mononitro-2,4-dimethylacetanilide isomer mixture 300 g (5.0 mols) of glacial acetic acid are initially introduced into a 1 l four-necked flask with a stirrer, condenser, dropping funnel and internal thermometer. 141 g of mononitro-2,4-dimethylaniline isomer mixture (prepared by nitration of 121 g=1.0 mol of 2,4-dimethylaniline) of the following composition: 90.2% by weight of <strong>[2124-47-2]5-nitro-2,4-dimethylaniline</strong>, 9.5% by weight of 3-nitro-2,4-dimethylaniline, and 0.3% by weight of 6-nitro-2,4-dimethylaniline are introduced into the flask at 20 C. 122 g (1.2 mols) of acetic anhydride are added dropwise to the mixture in the course of 1 hour, whilst cooling, and the temperature is not to rise above 55 C. The reaction mixture is then heated to boiling and is heated under reflux for 1 hour. 300 g is glacial acetic acid are then distilled off under normal pressure. The approximately 120 C. hot reaction solution is allowed to run into an initially introduced quantity of 1,500 g of water at 35 C., whilst stirring, and the temperature is not to rise above 60 C. The reaction mixture is cooled to 20 C., whilst stirring, and the precipitated product is filtered, washed with water until free from acetic acid and dried well under suction. Yield about 230 g of moist product with the relative composition given above.
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