Ethyl Bromide → 1-(1-Methoxyisopropoxy)pent-2-yne

참여 물질

반응 단계

0.89 g (127 mmol) of granulated lithium were added within 20 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 cyan solution of lithium in liquid ammonia was obtained. 6.34 g (92 mmol) of piperylene (=1,3-pentadiene) were added portion wise within 30 minutes. The end of the formation of lithium amide could be recognized by the discoloration of the reaction mixture. 10.1 g (71 mmol) of 3-(1-methoxy-1-methyl-ethoxy)-propyne (89.7% GC) were added with a dropping funnel to the reaction mixture at −37° C. within 30 minutes. The reaction mixture was held at −37° C. for about 1 hour. 14.0 g (126 mmol) of bromoethane were added with a dropping funnel to the reaction mixture within 30 minutes. The reaction mixture was subsequently stirred for 1 hour. 100 ml of n-hexane were added to the reaction mixture and the liquid ammonia was evaporated under normal pressure within 1.5 hours. 50 ml of water were added to the reaction mixture at 22° C., and the mixture was vigorously stirred until all salt was dissolved. The water layer was extracted once with 50 ml of 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. 11.3 g of crude 1-(1-methoxy-1-methyl-ethoxy)-pent-2-yne were obtained with a purity of 87.5% (yield 85.3% based on 3-(1-methoxy-1-methyl-ethoxy)-propyne).

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