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

Beteiligte Stoffe

Reaktionsschritte

259 mg (37 mmol) of granulated lithium were added within 5 minutes to 47.7 g (1.9 mol) of liquid ammonia at −40° C. The mixture was stirred until no more lithium floated (after approximately 10 minutes). A dark blue solution of lithium in liquid ammonia was obtained. 4.0 ml (40 mmol) of isoprene were added portion wise within 10 minutes. The end of the formation of lithium amide could be recognized by the discoloration of the reaction mixture. 2.9 g (20 mmol) of 3-(1-methoxy-1-methyl-ethoxy)-propyne (88.9% GC) were added with a dropping funnel to the reaction mixture at −40° C. within 20 minutes. The reaction mixture was held at −40° C. for about 1 hour. 8.9 g (80 mmol) of bromoethane were added with a dropping funnel to the reaction mixture within 10 minutes. The reaction mixture was subsequently stirred for 1 hour. 20 ml of n-hexane were added to the reaction mixture and the liquid ammonia was evaporated under normal pressure within 5 hours. 20 ml of water were added to the reaction mixture at 22° C., and the mixture was stirred until all salt was dissolved. The organic layer was separated and dried over 2 g of anhydrous magnesium sulfate. The solution was concentrated under reduced pressure (40° C., 40 mbar) and the crude product was analyzed by GC. 3.3 g of crude 1-(1-methoxy-1-methyl-ethoxy)-pent-2-yne were obtained with a purity of 75.6% (yield 80.0% based on 3-(1-methoxy-1-methyl-ethoxy)-propyne).

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