1-(2-BroMo-5-chlorophenyl)-3-Methyl-1H-pyrazole Chemical Properties

Boiling point:

344.8±37.0 °C(Predicted)

Density 

1.56±0.1 g/cm3(Predicted)

storage temp. 

Sealed in dry,Room Temperature

pka

0.02±0.12(Predicted)

1-(2-BroMo-5-chlorophenyl)-3-Methyl-1H-pyrazole Usage And Synthesis

Synthesis

Potassium tert-butoxide (Aldrich, 95%, 84.6 g, 0.716 mol) and DMSO (400 mL) were added to a 3L three-necked round-bottomed flask fitted with a mechanical stirrer, a temperature controller and a nitrogen inlet. The solution was stirred for 15 min at room temperature. To this solution, 3-methylpyrazole (59 g, 0.719 mol) was added and then washed with DMSO (50 mL). The resulting orange-colored turbid solution was stirred for 15 min, 1-bromo-4-chloro-2-fluorobenzene (100 g, 0.477 mol) was added, and then washed with DMSO (50 mL). The reaction mixture was heated to 50 °C and kept for 5 hours. After cooling to room temperature, the reaction mixture was diluted with MTBE (750 mL) and water (500 mL) was added to give a brown turbid mixture. After stirring for 15 min, the organic layer was separated and washed sequentially with 1N HCl (250 mL), brine (250 mL) and water (250 mL). The organic layer was analyzed by GC (>99% conversion, 83% and 17% yield of 1-(2-bromo-5-chlorophenyl)-3-methyl-1H-pyrazole and 1-(2-bromo-5-chlorophenyl)-5-methyl-1H-pyrazole, respectively). The MTBE solution was concentrated under vacuum to about 200 mL (KF showed 0.737% water). THF (500 mL) was added and concentrated to about 200 mL (KF = 0.158%). The THF addition and concentration steps were repeated to obtain a solution of ~200mL (KF=0.023%), which was used directly in the next step. Analytical samples of compounds 3 and 4 were purified and characterized by column chromatography: compound 3: white crystals; melting point: 76 °C (DSC onset temperature). 1H NMR (400 MHz, CDCl3) δ 7.80 (1H, d, J=2.3 Hz), 7.61 (1H, d, J=8.6 Hz), 7.58 (1H, d, J=2.5 Hz), 7.22 (1H, dd, J=8.6,2.6Hz), 6.27 (1H, d, J=2.5Hz), 2.38 (3H, s); 13C NMR (100MHz, CDCl3) δ 150.8, 140.6, 134.6, 134.1, 132.0, 129.0, 128.2, 115.4, 107.0, 13.6. Compound 4: white crystals; 1H NMR (400 MHz, CDCl3) δ 7.65 (1H, d, J=8.6 Hz), 7.62 (1H, d, J=1.5 Hz), 7.43 (1H, d, J=2.5 Hz), 7.35 (1H, dd, J=8.6,2.2 Hz), 6.21 (1H, s), 2.19 (3H. s); 13C NMR (100 MHz, CDCl3) δ 140.6, 140.2, 140.0, 134.1, 133.9, 130.8, 130.2, 120.7, 105.9, 11.4.

References

[1] Patent: US2009/62540, 2009, A1. Location in patent: Page/Page column 6-7
[2] Patent: US2009/88447, 2009, A1. Location in patent: Page/Page column 4
[3] Patent: WO2015/35113, 2015, A1. Location in patent: Page/Page column 71

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