反应详情

温度

-30 °C

1.3 mols of magnesium turnings are placed in a 3 L four-necked flask. 100 ml of tetrahydrofuran (THF) and a iodine crystal are added thereto. 50 ml of a 15% vinyl bromide solution in tetrahydrofuran are added with stirring and under nitrogen atmosphere. The solution immediately decolourizes, while the Grignard starts to form with an exothermic reaction: the mixture is cooled to −30° C. and one mol of beta-ionone dissolved in 500 ml of THF and 950 mL of the above 15% vinyl bromide solution are added at the same time through two dropping tunnels, at such a rate that temperature remains below −15 20° C. After completion of the addition, the cooling bath is removed and the reaction mixture is brought to room temperature. After 2 hours the reaction mixture is poured into 2 ml of ice-water containing 10 g of ammonium chloride under stirring, then is extracted with 700 ml of ethyl acetate. The organic phase is washed twice with 100 ml of 15% sodium chloride aqueous solution and dried over sodium sulfate. Solvent is evaporated off under reduced pressure and the resulting thick oil is distilled under vacuum, collecting 202 g of distillate, consisting of vinyl beta-ionol of purity higher than 95%, as determined by NMR analysis (yield: 87.5%).

1. customto form with an exothermic reaction
2. customremains below −15 20° C
3. additionAfter completion of the addition
4. customthe cooling bath is removed
5. customis brought to room temperature
6. additionAfter 2 hours the reaction mixture is poured into 2 ml of ice-water containing 10 g of ammonium chloride
7. stirringunder stirring
8. extractionis extracted with 700 ml of ethyl acetate
9. washThe organic phase is washed twice with 100 ml of 15% sodium chloride aqueous solution
10. dry with materialdried over sodium sulfate
11. customSolvent is evaporated off under reduced pressure
12. distillationthe resulting thick oil is distilled under vacuum
13. distillationcollecting 202 g of distillate