Ethanol → Methyl 1H-pyrazole-4-carboxylate

Temperature

80 °C

44.45 g of methyl 3,3-dimethoxypropionate and 45 ml of methyl formate was dissolved to 180 ml of dimethoxyethane. Under nitrogen atmosphere, 12.8 g of 60% sodium hydride was added to the solution keeping the temperature of the solution at 40 to 50° C. during addition. Then the mixture was stirred at room temperature for 18 hours. 180 ml of diethylether was added to the reaction mixture, as a result, a solid was formed. The solid was collected by filteration, followed by washing with 60 ml of diethylether. The obtained solid was dried under reduced pressure for overnight to obtain 49.41 g of methyl 2-(dimethoxymethyl)-3-hydroxy-acrylate sodium salt. 9.91 g of methyl 2-(dimethoxymethyl)-3-hydroxy-acrylate sodium salt was suspended to 100 ml of ethanol. 2.50 g of hydrazine hydrate was added to the suspension, followed by stirring at room temperature for 3 hours and at 80° C. for 1 hour. 100 ml of water was added to the reaction mixture which was cooled to room temperature. The mixture was concentrated under reduced pressure to about 100 ml. The concentrated solution was extracted by ethyl acetate. The organic layer was washed with saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was dissolved to ethyl acetate, activated carbon was added to it, and stirred for overnight. The suspension was filtered. The filtrate was concentrated under reduced pressure. The residue was recrystallized from hexane-ethyl acetate to obtain 1.40 g of 4-methoxycarbonyl-1H-pyrazole.

1. temperaturewas cooled to room temperature
2. concentrationThe mixture was concentrated under reduced pressure to about 100 ml
3. extractionThe concentrated solution was extracted by ethyl acetate
4. washThe organic layer was washed with saturated aqueous solution of sodium chloride
5. dry with materialdried over anhydrous magnesium sulfate
6. filtrationfiltered
7. concentrationconcentrated under reduced pressure
8. dissolutionThe residue was dissolved to ethyl acetate, activated carbon
9. additionwas added to it
10. stirringstirred for overnight
11. filtrationThe suspension was filtered
12. concentrationThe filtrate was concentrated under reduced pressure
13. customThe residue was recrystallized from hexane-ethyl acetate

ORD record

ord-4e8ed68ea7804f3ea620ff2bee6e1ee7

Source dataset

uspto-grants-2009_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07541374B2