Hydrazine hydrate (1:1) → 3,5-diethyl-1H-pyrazole

A solution of 3,5-heptanedione (10.0 g, 0.078 mmol) in ethanol (40 ml) was treated dropwise with hydrazine hydrate (4.2 ml, 0.086 mmol) at room temperature producing an exotherm that was cooled by use of an ice bath. After the addition was complete the reaction mixture was allowed to warm to room temperature. The solution was concentrated under reduced pressure. The oil was partitioned between dichloromethane and brine. The aqueous layer was extracted with dichloromethane (×2). The combined organic phases were dried over anhydrous magnesium sulphate, filtered and evaporated under reduced pressure to afford the title compound (9.66 g) as a pale yellow oil that partly solidified on standing.

1. customproducing an exotherm that
2. temperaturewas cooled by use of an ice bath
3. additionAfter the addition
4. concentrationThe solution was concentrated under reduced pressure
5. customThe oil was partitioned between dichloromethane and brine
6. extractionThe aqueous layer was extracted with dichloromethane (×2)
7. dry with materialThe combined organic phases were dried over anhydrous magnesium sulphate
8. filtrationfiltered
9. customevaporated under reduced pressure

ORD record

ord-49192e68d71e4e3aaa4eaba0aa64a8da

Source dataset

uspto-grants-2004_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06750230B2