1-Isobutyl-1H-pyrazole synthesis
- Product Name:1-Isobutyl-1H-pyrazole
- CAS Number:725746-81-6
- Molecular formula:C7H12N2
- Molecular Weight:124.18
Yield:725746-81-6 100%
Reaction Conditions:
with sodium hydroxide;tetrabutylammomium bromide in water;methyl cyclohexane at 110; for 5.5 h;Product distribution / selectivity;Heating / reflux;
Steps:
1.1
Isobutyl bromide (176 ml, 1.62 mol), tetra-n-butylammonium bromide (4.8 g, 0.015 mol) and 40% aqueous sodium hydroxide solution (192 ml, 2.94 mol) were added to a solution of 1H-pyrazole (100.0 g, 1.47 mol) in methylcyclohexane (200 ml) and the mixture was refluxed for 5.5 hours while violently stirring at an oil bath temperature of 110°C. After the mixture was cooled to room temperature, the organic phase was separated and washed with water and then brine. The thus obtained organic phase was dried over anhydrous magnesium sulfate and concentrated to obtain the desired compound (183.1 g, 1.47 mol) containing approximately 0.5% of methylcyclohexane. Yield: 100% Mass (EI); M/z: 124 (M+), 109, 81. NMR (200 MHz, CDCl3); δ (ppm): 0.90 (6H, d, J=6.9 Hz), 2.21 (1H, brhep, J=6.9 Hz), 3.92 (2H, d, J=7.3 Hz), 6.23 (1H, dd, J=1.7 Hz, J=2.1 Hz). 7.35 (1H, d, J=2.1 Hz), 7.50 (1H, d, J=1.7 Hz).
References:
EP1580189,2005,A1 Location in patent:Page/Page column 31
288-13-1
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