2,3-Dihydroxybenzoic Acid → Methyl 2,3-Dihydroxybenzoate

Participants

Reaction Steps

50 g of 2,3-dihydroxybenzoic acid in 450 ml of methanol is mixed drop by drop with 50 ml of thionyl chloride at room temperature. Then, the solution is heated for five hours to 60° C. and still stirred overnight at room temperature. The solvent is completely removed in a vacuum, and the remaining oil is taken up in diethyl ether and extracted with saturated sodium bicarbonate solution. After washing with brine, drying with sodium sulfate and removal of the solvent in a vacuum, 46 g of 2,3-dihydroxybenzoic acid-methyl ester is obtained. The latter is mixed in 575 ml of DMF and 20.2 ml of dibromomethane with 56.7 g of potassium carbonate, and it is heated for five hours under argon to 100° C. Then, it is stirred overnight at room temperature. After mixing with water, it is extracted three times with ethyl acetate. The organic phase is washed several times with water and dried on sodium sulfate. The solvent is removed in a vacuum, and 50.2 g of 1,3-benzodioxole-4-carboxylic acid-methyl ester is obtained as a brown solid.

Provenance & Evidence