反应详情

A solution of 16.7 g of 4-formylcinnamic acid dimethyl acetal in 200 ml of dioxane was hydrogenated in the presence of 1 g of 5% palladium-on-carbon at room temperature and atmospheric pressure. After about 61/2 hrs., the theoretical volume of hydrogen was consumed and the uptake ceased. The reaction mixture was filtered through Celite and the filter cake was washed with 300 ml of dioxane. The filtrate was concentrated to a final volume of 200 ml, 200 ml of 1N hydrochloride acid was added, the solution was stirred at room temperature for 4 hrs. and then evaporated to dryness. The residue was dissolved in 700 ml of methylene chloride, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated to a final volume of 100 ml and the solution was allowed to stand at 0° for 16 hrs. The precipitate was collected, washed with 1:1 methylene chloride-petroleum ether and dried at 55° for 4 hrs. under vacuum to give 10.9 g (81%) of 4-formyldihydrocinnamic acid as colorless crystals, m.p. 134°-138°.

1. custom2 hrs
2. custom, the theoretical volume of hydrogen was consumed
3. filtrationThe reaction mixture was filtered through Celite
4. washthe filter cake was washed with 300 ml of dioxane
5. concentrationThe filtrate was concentrated to a final volume of 200 ml, 200 ml of 1N hydrochloride acid
6. additionwas added
7. customand then evaporated to dryness
8. dissolutionThe residue was dissolved in 700 ml of methylene chloride
9. dry with materialdried over anhydrous sodium sulfate
10. filtrationfiltered
11. concentrationThe filtrate was concentrated to a final volume of 100 ml
12. waitto stand at 0° for 16 hrs
13. customThe precipitate was collected
14. washwashed with 1:1 methylene chloride-petroleum ether
15. customdried at 55° for 4 hrs