反应详情

50 g (0.35 mol) of kojic acid (1) was added to 200 ml of water and the pH of the solution was adjusted to 8.5 using 50% aqueous sodium hydroxides. 37% Formaldehyde (30 ml) was added and the solution allowed stirring 12 hrs. The reaction mixture was acidified to pH 1 with 37% hydrochloric acid and concentrated in vacuo to dryness. The residue was extracted with 2×200 ml of isopropanol at 90° C. The isopropanol extracts were combined and concentrated to yield the crude product (2) (55.4 g, 92%). Recrystallisauon from isopropanol afforded the analytically pure compound as colourless needles. m.p. 160-161° C.

1. concentrationconcentrated in vacuo to dryness
2. extractionThe residue was extracted with 2×200 ml of isopropanol at 90° C
3. concentrationconcentrated
4. customto yield the crude product (2) (55.4 g, 92%)