反应详情

A mixture of finely powdered malonic acid (10.4 g, 0.1 mol), 2,2,2-trichloroethanol (9.6 mL, 0.1 mol) and p-toluenesulfonic acid monohydrate (570 mg, 3% in benzene (30 mL) was stirred under azeotropic reflux for 26 hours, then cooled at room temperature. The unreacted malonic acid (4.6 g) was filtered and washed with benzene (2×10 mL). Water (50 mL) was added to the filtrate followed by portionwise addition of sodium bicarbonate until a basic pH was reached. The aqueous phase was decanted, washed with ether (3×50 mL), then acidified with concentrated aqueous HCl and extracted with methylene chloride (4×50 mL). The combined extracts were washed with brine (25 mL), dried over MgSO4, filtered and evaporated in vacuo to give 2,2,2-trichloroethyl hydrogen malonate (4.34 g, 18.4 mmol, 18%) that slowly crystallized; m.p. 42°-43°; NMR (CDCl3): δ11.0 (S, CO2H), 4.83 (S, --OCH2CCl3 ), 3.61 (S, --O2C--CH2CO2 --).

1. temperatureunder azeotropic reflux for 26 hours
2. filtrationThe unreacted malonic acid (4.6 g) was filtered
3. washwashed with benzene (2×10 mL)
4. additionWater (50 mL) was added to the filtrate
5. additionfollowed by portionwise addition of sodium bicarbonate until a basic pH
6. customThe aqueous phase was decanted
7. washwashed with ether (3×50 mL)
8. extractionextracted with methylene chloride (4×50 mL)
9. washThe combined extracts were washed with brine (25 mL)
10. dry with materialdried over MgSO4
11. filtrationfiltered
12. customevaporated in vacuo