Hydroxyphenylacetic acid → 3-(3,5-Dimethoxyphenyl)-2-(4-hydroxyphenyl)-acrylic acid

Participants

Reaction Conditions

Reaction Steps

To a mixture of 3,5-dimethoxybenzaldehyde (120 g, 0.72 mol) and p-hydroxyphenyl acetic acid (110 g, 0.72 mol) was added acetic anhydride (240 mL) and triethylamine (161 mL, 1.6 equiv.). This non-homogeneous mixture on heating becomes homogeneous at ˜70° C. After being stirred at 130° C. for 4 hr, the mixture was cooled to room temperature. HCl (15%, 500 mL) was added to the reaction mixture slowly in 30 min keeping temperature below 5-10° C. The solid was dissolved in 3N aqueous NaOH (1.2 L) and stirred for 0.5 hr. The filtrate was acidified, maintaining a temperature at 25-30° C., with conc. HCl (˜700 mL) to pH 1. The precipitated product was filtered and washed with water to give crude product (˜300 g, wet cake). The crude product was dissolved by heating in ethanol and recrystallized by adding equal volume of water. The product was dried overnight in a vacuum oven at 40° C. Yield: 161 g, 74%. Analysis: 1HNMR (DMSO-d6): δ 12.48 (br, 1H), 9.42 (s, 1H), 7.59 (s, 1H), 6.95 (d, J=8.0 Hz, 2H), 6.76 (d, J=8.0 Hz, 2H), 6.35 (t, J=2.2 Hz, 1H), 6.27 (d, J=2.2 Hz, 2H), 3.56 (s, 6H).

Provenance & Evidence