Related Products of 288-32-4, These common heterocyclic compound, 288-32-4, name is 1H-Imidazole, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.
Example 1; Inventive; A flask is charged with 531.5 g of dry dichloromethane and 93.8 g (1.37 mol) of imidazole and this initial charge is heated to 35 C. At this temperature over the course of 1.75 hours 36.04 g (0.36 mol) of phosgene are added with an introduction rate of 20.6 g/h. The mixture thus obtained is subsequently stirred at the same temperature for 1.5 h. In order to ensure a phosgene-free reaction mixture, 13.2 g of distillate are taken off under a pressure of 790 to 500 mbar and at 35-25 C., an ammonia/water/isopropanol mixture is added to the distillate, and this mixture is discarded. The imidazole hydrochloride by-product (isolated dry weight: 72.1 g) is removed by filtration at 35 C., the filter cake being washed with twice 100 ml of warm dichloromethane at 33 C. 250.1 g of water-clear solution are distilled off from the combined organic phases at 790 to 500 mbar and 35-25 C. The remaining solution is cooled to 0 C., and a suspension forms. The precipitated carbonyl bisimidazole is separated off by filtration and additionally washed with 50 ml of dichloromethane conditioned to a temperature of 0 C. Drying of the crystals at 4 mbar and 30 C. gives 40.0 g of product in the form of white crystals, Hazen colour number: 69.7. The purity of the product is 99.3%, corresponding to a yield of 71.2% of theory.; Example 5 Inventive with Recycling of the Mother Liquor 1st Phosgenation A flask is charged with 531.5 g of dry dichloromethane and 93.8 g (1.37 mol) of imidazole and this initial charge is heated to 35 C. At this temperature over the course of 1.75 hours 35.02 g (0.35 mol) of phosgene are added with an introduction rate of 20.0 g/h. The mixture thus obtained is subsequently stirred at the same temperature for 1.5 h. In order to ensure a phosgene-free reaction mixture, 8.4 g of distillate are taken off under a pressure of 750 to 500 mbar and at 35-20 C., an ammonia/water/isopropanol mixture is added to the distillate, and this mixture is discarded. The imidazole hydrochloride by-product (isolated dry weight: 80.3 g) is removed by filtration at 35 C., the filter cake being washed with twice 100 ml of warm dichloromethane at 33 C. The remaining solution is cooled to 0 C., and a suspension forms. The precipitated carbonyl bisimidazole is separated off by filtration and additionally washed with 50 ml of dichloromethane conditioned to a temperature of 0 C. After the solid carbonylbisimidazole has been filtered off, 553.0 g of mother liquor M1 are obtained. Drying of the crystals at 5 mbar and 20 C. gives 33.54 g of product in the form of white crystals with a Hazen colour number of 45.1. The purity of the product is 99.6%. The yield therefore corresponds to 59.9% of theory. 2nd Phosgenation A flask is charged with 531.5 g of dichloromethane-containing mother liquor M1 from the 1st phosgenation step and 93.8 g (1.37 mol) of imidazole and this initial charge is heated to 35 C. At this temperature over the course of 1.75 hours 35.02 g (0.35 mol) of phosgene are added with an introduction rate of 20.0 g/h. The mixture thus obtained is subsequently stirred at the same temperature for 1.5 h. In order to ensure a phosgene-free reaction mixture, 21.6 g of distillate are taken off under a pressure of 750 to 450 mbar and at 35-20 C., an ammonia/water/isopropanol mixture is added to the distillate, and this mixture is discarded. The imidazole hydrochloride by-product (isolated dry weight: 86.6 g) is removed by filtration at 35 C., the filter cake being washed with twice 100 ml of warm dichloromethane at 33 C. The remaining solution is cooled to 0 C., and a suspension forms. The precipitated carbonyl bisimidazole is separated off by filtration and additionally washed with 100 ml of dichloromethane conditioned to a temperature of 0 C. After the solid carbonylbisimidazole has been filtered off, 553.0 g of mother liquor M2 are obtained. Drying of the crystals at 6 mbar and 30 C. gives 39.4 g of product in the form of white crystals with a Hazen colour number of 33.2. The purity of the product is 98.7%. The yield therefore corresponds to 70% of theory. 3rd Phosgenation A flask is charged with 531.5 g of dichloromethane-containing mother liquor M2 from the 2nd phosgenation step and 93.8 g (1.37 mol) of imidazole and this initial charge is heated to 35 C. At this temperature over the course of 1.75 hours 35.02 g (0.35 mol) of phosgene are added with an introduction rate of 20.0 g/h. The mixture thus obtained is subsequently stirred at the same temperature for 1.5 h. In order to ensure a phosgene-free reaction mixture, 9.2 g of distillate are taken off under a pressure of 750 to 500 mbar and at 35-20 C., an ammonia/water/isopropanol mixture is added to the distillate, and this mixture is discarded. The imidazole hydrochloride by-product (isolated dry weight: 88.1 g) is removed by filtration at 35 C., the filter cake being washed with twice 100 ml of warm dichloromethane at 33 C. The remaining solution is cooled to 0 …
The synthetic route of 288-32-4 has been constantly updated, and we look forward to future research findings.
Reference:
Patent; Job, Andreas; Griehsel, Bernd; US2005/272937; (2005); A1;,
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem