Formaldehyde → 1,3-Dihydro-1-oxoisobenzofuran-5-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

Oleum (20-25% SO3 43 kg) is charged into a reactor. Terephthalic acid (13 Kg) and then paraformaldehyde (3.8 Kg) is added. The mixture is agitated at 138-148° C. for 4½ hours. Water (87 L) is added and the temperature is adjusted to about 100° C. The precipitate is filtered of, washed with water and suspended in water. The pH of the suspension is adjusted to about 7 with NaOH (about 10%), activated carbon, 0.5 Kg is added, and then the mixture is filtered, the precipitate is rinsed with water. The temperature of the filtrate is adjusted to about 85° C. and the pH is adjusted to about 2 with 96% sulfuric acid. The 5-carboxyphthalide precipitated is separated by filtration washed and dried. Yield 82%.

Provenance & Evidence