4-Hydroxybenzoic Acid → 4-(Prop-2-en-1-yloxy)benzoic acid

Participants

Reaction Conditions

Reaction Steps

4-(2-Propenyloxy)benzoic acid was synthesized by Apfel's method (Apfel et al, Anal. Chem., 1985, 57, 651-658). A 1 L three-neck round-bottom flask was equipped with a condenser, 150 mL additional funnel, heating bath, and magnetic stirrer. 90 g (0.65 mol) of 4-hydroxybenzoic acid and 400 mL of methanol were added at 25° C. and stirred. After the acid was dissolved, 105 g (1.9 mol) of potassium hydroxide in 125 mL of distilled water was added dropwise. The reaction mixture was heated to reflux, and 90 g (0.74 mol) of allyl bromide was then added over a 2 hour period. The reaction mixture was allowed to reflux for 8 hours. As the reaction proceeded, potassium bromide precipitated. From this mixture, 250 mL of methanol was removed by evaporation. The remainder of the reaction mixture was cooled to 25° C. and then added to 2.5 L of distilled water. Hexane (250 mL) was added to extract organic impurities. After discarding the organic phase, the aqueous phase was heated to 40° C. and neutralized with 300 mL of 20% HCl. The crude product precipitated during the neutralization, was subsequently collected by filtration and purified by recrystallization from ethanol. Yield: 46 g (40.2%), mp 165° C.

Provenance & Evidence