反应详情

90 g of polyphosphoric acid were placed in a 350 ml sulphonation flask. Then, it was treated dropwise with a solution of 10.0 g (47 mmol) of 2-(p-fluorophenyl)-3-hydroxy-3-methylbutyric acid in 70 ml of CH2CL2 at 20-25°. The viscous, yellow colored mixture was stirred for 2 hours, with the temperature rising to 35°. After hydrolysis with ice-water the mixture was left to stand overnight and then treated with ether. The organic phase was separated, washed 3 times with water, dried over MgSO4, filtered and the filtrate was concentrated. The residue was dissolved in CH2CL2 and the solution was treated with hexane and concentrated on a rotary evaporator until crystallization occurred. After standing at RT for 1 hour the crystals were filtered off under suction and washed with cold hexane. There were obtained 67 g (73%) of 2-(p-fluorophenyl)-3-methylcrotonic acid as a white powder.

1. customrising to 35°
2. waitwas left
3. waitto stand overnight
4. customThe organic phase was separated
5. washwashed 3 times with water
6. dry with materialdried over MgSO4
7. filtrationfiltered
8. concentrationthe filtrate was concentrated
9. dissolutionThe residue was dissolved in CH2CL2
10. additionthe solution was treated with hexane
11. concentrationconcentrated on a rotary evaporator until crystallization
12. waitAfter standing at RT for 1 hour
13. filtrationthe crystals were filtered off under suction
14. washwashed with cold hexane