反应详情

Sodium hydrate—60% in oil dispersion (100.0 g, 2.5 mol) was weighed into a 5-liter three-necked reaction flask and the metal hydride washed three times with 300-mL portions of pentane under nitrogen. The washed sodium hydride was covered with a solution of dry reagent grade tetrahydrofuran (900 mL) and dimethyl carbonate (900 g, 10.0 mol). The sodium hydride was activated by the dropwise addition of anhydrous methanol (1.5 mL) followed by a few grams of 5-acetyl-2,2,5-trimethyl-1,3-dioxane in tetrahydrofuran. The reaction mixture was held under reflux with constant stirring in a nitrogen atmosphere while 5-acetyl-2,2,5-trimethyl-1,3-dioxane dissolved in tetrahydrofuran (800 mL) was added dropwise (ca. 0.5 hr.). The reaction was stirred for another hour after which time the mixture was allowed to cool to room temperature. Anhydrous methanol (100 mL) was added to the mixture to decompose residual sodium hydride followed by glacial acetic acid (150 mL) to quench the anion. The quenched reaction was poured into one liter of cold water and the product extracted with ligroin. The ligroin extract was washed with saturated sodium bicarbonate solution, dried over magnesium sulfate, filtered, and flash evaporated in vacuio to yield 203 g of crude product. The brown-colored mobile oil was purified to yield a water white liquid by distillation; b.p. 102-5° C.; 130 g, 57% of theoretical yield; H-NMR spectra were consistent. Elemental Analysis calculated for C11H18O5: C,57.38; H, 7.88. Found: C, 57.67; H, 7.98.

1. washthe metal hydride washed three times with 300-mL portions of pentane under nitrogen
2. temperatureunder reflux
3. additionwas added dropwise (ca. 0.5 hr.)
4. customto quench the anion
5. customThe quenched reaction
6. extractionthe product extracted with ligroin
7. extractionThe ligroin extract
8. washwas washed with saturated sodium bicarbonate solution
9. dry with materialdried over magnesium sulfate
10. filtrationfiltered
11. customflash evaporated in vacuio
12. customto yield 203 g of crude product
13. customThe brown-colored mobile oil was purified
14. customto yield a water white liquid
15. distillationby distillation