Synthetic Route of 13808-64-5, The chemical industry reduces the impact on the environment during synthesis 13808-64-5, name is 4-Bromo-3-methylpyrazole, I believe this compound will play a more active role in future production and life.
(1) Combine 16.1 g (0.1 mol) of 4-bromo-3-methyl-1H-pyrazole, 10.1 g (0.12 mol) of 3,4-dihydro-2H-pyran, and 0.7 g (0.006 mol) of trifluoroacetic acid ) Add to the reaction bottle and stir to heat to micro-reflux for 12 hours. The reaction formula is as follows:Cool to room temperature, add 0.24 g (0.006 mol) of sodium hydride to neutralize the reaction system,Vacuum distillation to obtain intermediate4-bromo-3-methyl-1- (tetrahydro-2H-pyran-2-yl) -1H-pyrazole and4-bromo-5-methyl-1- (tetrahydro-2H-pyran-2-yl) -1H-pyrazole total 24 grams,The presence of isomers does not affect the next reaction. (2) The intermediates obtained in step (1) 4-bromo-3-methyl-1- (tetrahydro-2H-pyran-2-yl) -1H-pyrazole and 4-bromo-5- Methyl-1- (tetrahydro-2H-pyran-2-yl) -1H-pyrazole 24 g was dissolved in 200 ml of THF, cooled to minus 75 degrees, and n-butyl with a concentration of 2.5 mol / L was added dropwise 48 ml (0.12 mol) of lithium solution, maintaining the temperature at minus 75 degrees Celsius, dropping and holding for half an hour, then adding 14 g (0.12 mol) of N-formylmorpholine at this temperature, the reaction formula in step (2) is as follows :After the reaction is completed, naturally warm to room temperature, add dilute sulfuric acid to quench until the system pH value is less than 1, stir at room temperature for 3-4 hours, neutralize with sodium bicarbonate, extract with ethyl acetate, dry and concentrate to obtain the target product by adsorption and purification on silica gel 3-Methyl-1H-pyrazole-4-carbaldehyde 8 g.The yield of the target product 3-methyl-1H-pyrazole-4-carbaldehyde in this example was 72.7%. 2 is the nuclear magnetic resonance spectrum of the product 3-methyl-1H-pyrazole-4-carbaldehyde obtained in this example;
In the field of chemistry, the synthetic routes of compounds are constantly being developed and updated. I will also mention this compound in other articles, 4-Bromo-3-methylpyrazole, other downstream synthetic routes, hurry up and to see.