Water → 3-Bromo-6-propylpyridazine

Temperature

80 °C

11.75 g of 6-propyl-3(2H)-pyridazinone were dissolved in 70 ml of absolute toluene while warming in a sulphonation flask under nitrogen, heated to 80° C. and treated dropwise while stirring well within 30 minutes with a solution of 24.4 g of phosphorus oxybromide in 24.4 g of absolute toluene. The mixture was subsequently stirred under reflux for a further 3 hours. After completion of the reaction, the mixture was poured into 200 ml of water and neutralized with solid sodium hydrogen carbonate. The phases were separated and the aqueous phase was back-extracted twice with 100 ml of tert.butyl methyl ether each time. The combined organic phases were washed with 100 ml of water and dried over sodium sulphate. After evaporation of the solvent, the dark brown crystalline residue (14.1 g) was sublimed at 40°-60° C. in a high vacuum, there being obtained 8.2 g (48%) of 3-bromo-6-propylpyridazine as white crystals of melting point 35°-36° C.

1. temperaturewhile warming in a sulphonation flask under nitrogen
2. additiontreated dropwise
3. temperatureunder reflux for a further 3 hours
4. customAfter completion of the reaction
5. customThe phases were separated
6. extractionthe aqueous phase was back-extracted twice with 100 ml of tert.butyl methyl ether each time
7. washThe combined organic phases were washed with 100 ml of water
8. dry with materialdried over sodium sulphate
9. customAfter evaporation of the solvent
10. customwas sublimed at 40°-60° C. in a high vacuum

ORD record

ord-718d583c445040caa88924dcb877be55

Source dataset

uspto-grants-1986_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04595521