Acetylene → 1-(4-Fluorophenyl)prop-2-yn-1-ol

Participants

Reaction Conditions

Reaction Steps

A 200 ml. volume of dry tetrahydrofuran was cooled to -60° C. in a dry ice/acetone bath and then acetylene gas was passed into the solvent until 8.0 g (0.307 mole) had dissolved. The resulting solution was then added to a second 200 ml. portion of dry tetrahydrofuran cooled to -70° C. in a flame-dried 1-liter three-necked, round bottomed reaction flask equipped with magnetic stirrer, addition funnel and nitrogen inlet tube to provide a dry nitrogen atmosphere. To this solution, there was then slowly added 99 ml. of a 2.22 molar solution of n-butyl lithium (0.22 mole) at such a rate that the internal temperature remained below -65° C. After the addition was complete, a solution consisting of 24.82 g (0.20 mole) of p-fluorobenzaldehyde dissolved in 80 ml. of tetrahydrofuran was added at such a rate that the internal temperature again remained below -65° C. The reaction mixture was then stirred at -72° C. for a period of 30 minutes and then allowed to warm up to +5° C. during another 30 minute period. The reaction was then quenched with 80 ml. of water, followed by the addition of anhydrous potassium carbonate to form a pasty mass and an organic supernatant liquid. The organic layer was decanted and combined with two subsequent ether washes of the potassium carbonate mass. The resulting orange solution was then dried over fresh anhydrous potassium carbonate for a period of approximately 16 hours (overnight) and subsequently distilled in vacuo to give 20.5 g (68%) of pure 1-hydroxy-1-(p-fluorophenyl)-2-propyne, b.p. 98°-101° C./8 mm. Hg. A second preparation gave a 92% yield of pure product (b.p. 104° C./9 mm. Hg).

Provenance & Evidence