反应详情

0.89 g (127 mmol) of granulated lithium were added within 15 minutes to 100 ml (4 mol) of liquid ammonia at −37° C. The mixture was stirred until no more lithium floated (after approximately 15 minutes). A dark blue solution of lithium in liquid ammonia was obtained. 5.94 g (86.3 mmol) of isoprene were added portion wise within 30 minutes. The end of the formation of LiNH2 could be recognized by the de-coloration of the reaction mixture and 10.69 g (70.1 mmol) of 3-(1-methoxy-1-methyl-ethoxy)-propyne were added to the reaction mixture at −37° C. within 30 minutes. The reaction mixture was held at −37° C. for about 1 hour. Ethyl iodide (20.05 g, 126 mmol) was added with a dropping funnel to the reaction mixture within 30 minutes. The reaction mixture was subsequently stirred for 1 hour. n-Hexane (100 ml) was added to the reaction mixture and the liquid ammonia was evaporated under normal pressure within 1.5 hours. Water (50 ml) was added to the reaction mixture at 22° C., and the mixture was vigorously stirred until all salt was dissolved. The water layer was extracted twice with 50 ml n-hexane. The organic layer was dried over 5 g of anhydrous sodium sulfate. The solution was concentrated under reduced pressure (40° C., 60 mbar) and the crude product was analyzed by GC. Crude 1-(1-methoxy-1-methyl-ethoxy)-pent-2-yne (13.21 g) were obtained with a purity of 72.95% (88.0% yield based on 3-(1-methoxy-1-methyl-ethoxy)-propyne).

1. additionwere added to the reaction mixture at −37° C. within 30 minutes
2. customthe liquid ammonia was evaporated under normal pressure within 1.5 hours
3. additionWater (50 ml) was added to the reaction mixture at 22° C.
4. stirringthe mixture was vigorously stirred until all salt
5. dissolutionwas dissolved
6. extractionThe water layer was extracted twice with 50 ml n-hexane
7. dry with materialThe organic layer was dried over 5 g of anhydrous sodium sulfate
8. concentrationThe solution was concentrated under reduced pressure (40° C., 60 mbar)