Trimethoxybenzaldehyde [3 from 5hydroxyvanillin

Into a 1-1. round-bottomed flask equipped with a magnetic stirrer and a reflux condenser were placed: 50 g (0.298 mol) 5-hydroxyvanillin, 500 ml acetone, 91.0 g (0.716 mol) dimethylsul-fate, 100 g (0.806 mol) finely ground Na2C03.H20, 10 ml of 10% KOH in methanol. Of course equimolar amounts of anhydrous Na2C03 or K2C03 can be used. The heterogenous mixture was stirred under vigorous reflux for 24 hours, after which the reflux condenser was replaced with a descending condenser. The solvent was distilled at a bath temp, of ca. 100° until the distillation ceased. To the solid residue was added 400 ml of water and the heterogenous mixture was stirred VIGOROUSLY for 2 hours at room temperature followed by one hour at 0-5° (ice-cooling). The light brown crystals were filtered by suction, washed with 3*150 ml of ice water and air dried to constant weight. Yield 55.1 g (94%), m.p. 72.5-74°. After distillation at 0.5mm/130°, there was obtained a 90% yield of 3,4,5-trimethoxybenzaldehyde, m.p. 73.5-75, VPC purity 99.3%. (This distillation is probably unnecessary, because the aldehyde is already quite pure).

[7] Tetrahedron Letters, Vol. 34, No. 6, pp.1007-1010, (1993)

[8] Pihkal, #72 Online - Pihkal can be found at

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