| 90.3% |
With sodium chlorite; sodium dihydrogenphosphate; 2-methyl-but-2-ene In water; <i>tert</i>-butyl alcohol at 20℃; for 14h; |
7.1; 43.1 5-chloro-1-methyl-3-(trifluoromethyl)-1H-pyrazole-4-carboxylic acid (Compound I-7B)
Add the compound 5-chloro-1-methyl-3-(trifluoromethyl)-1H-pyrazole-4-carbaldehyde (700mg, 3.30mmol) to tert-butanol (20mL) and water (5mL) at room temperature Add 2-methyl-2-butene (1.80 g, 25.7 mmol), sodium chlorite (1.48 g, 16.4 mmol), sodium dihydrogen phosphate (3.10 g, 25.8 mmol), and stir at room temperature for 14 hours. Dilute with water (50mL), extract with ethyl acetate (30mL×3), separate, combine the organic phases, dry the organic phase with anhydrous sodium sulfate, filter, and concentrate to obtain a colorless liquid crude residue, which is separated by a silica gel column Purification (petroleum ether: ethyl acetate (V/V) = 1:1) to obtain a colorless solid 5-chloro-1-methyl-3-(trifluoromethyl)-1H-pyrazole-4-carboxylic acid (compound I-7B) (680 mg, yield 90.3%). |
| 80% |
With sodium hydroxide; dihydrogen peroxide In water at 40 - 50℃; for 2h; |
5 EXAMPLE 5
EXAMPLE 5 10 g of 5-chloro-1-methyl-3-trifluoromethylpyrazol-4-carboaldehyde was added to an aqueous solution of 5 g of sodium hydroxide (2 equivalents to the amount of the aldehyde) in 50 ml of water.While stirring the resulting solution vigorously, 34.4 g of 35% hydrogen peroxide was added, in eight portions, over 1.5 hours at 40° C. to 50° C. After the completion of the dropping, the solution was stirred for 30 minutes, cooled to 15° C. and adjusted PH to 1 with concentrated hydrochloric acid.The crystals obtained were sufficiently washed with water and dissolved in ether.The ether solution was dried over anhydrous magnesium sulfate and further treated with active carbon.Ether was distilled out under reduced pressure to give 8.6 g of the target compound.Melting point: 197.5-199.5° C. Yield: 80.0%. Applicability in Industry The 4-cyanoacetylpyrazoles of the present invention, represented by Formula (1), are useful as intermediates for producing agricultural chemicals and drugs, for example for producing insecticides and acarcides described in Japanese Patent Laid-open No. Hei 11-269173 and patent application ser. No. 2000-178334. According to the present invention, 4-cyanoacetylpyrazoles useful as intermediates for producing compounds with insecticidal and acaricidal activities can be produced by an industrially advantageous process using easily available starting materials. The present invention does not use at all reaction solvents, such as toluene or ethylene dichloride, heavy metal oxidizing agents or heavy metal catalysts, which known processes have adopted.Use of water as a reaction solvent and only hydrogen peroxide as an oxidizing agent allows an industrially advantageous process to produce substituted pyrazole-4-carboxylic acids. |
| 72.5% |
With potassium permanganate; water at 70 - 80℃; for 8h; |
1.3 Preparation of 1-methyl-3-trifluoromethyl-5-chloro-4-pyrazole acid intermediates:
In a 500 mL three-necked flask, add 0.05 mol of 1-methyl-3-trifluoromethyl-5-chloro-4-pyrazole and 100 mLWater, slowly dropping 0.075 mol KMnO4 200 mL of aqueous solution for oxidation. Drop complete, heating to 70 ~ 80° C for 8 h. After slow cooling, the pH of the reaction solution was adjusted to alkaline with 10% KOH solution, and the insolubility was removed by filtration Acidification of the filtrate with concentrated hydrochloric acid, precipitation of white solid, filtration, washing, drying, in a white solid; yield: 72.5%. |
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