2-Ethyl-4-ethoxy-5-methoxybenzaldehyde

A solution of 7.3 g of 3-ethoxy-5-hydroxy-4-methoxybenzaldehyde in 100 mL acetone was treated with 5 mL methyl iodide and 8.0 g finely powdered anhydrous K2CO, and held at reflux on a steam bath for 6 h. The solvent was removed under vacuum, and the residue was suspended in H20. After making this strongly basic, it was extracted with 3x50 mLCH,CL, the extracts were pooled, and the solvent removed under vacuum. The residual amber oil was distilled at 110-120 °C at 0.4 mm/Hg to yield 7.3 g of a white oil. This spontaneously set to white crystals of 3,4-dimethoxy-5-ethoxybenzaldehyde which had a mp of 49-49.5 °C. Anal. (CmHi (04) C,H. This same aldehyde can be obtained, but in a less satisfactory yield, by the ethylation of 3,4-dimethoxy-5-hydroxybenzaldehyde described under the preparation of metaproscaline (MP). 

SYNTHESIS A solution of 83 g bourbonal (also called ethyl vanillin, or vanillal, or simply 3-ethoxy-4-hydroxybenzaldehyde) in 500 mL MeOH was treated with a solution of 31.5 g KOH pellets (85% material) dissolved in 250 mL H20. There was then added 71 g methyl iodide, and the mixture was held under reflux conditions for 3 h. All was added to 3 volumes of H20, and this was made basic with the addition of 25% NaOH. The aqueous phase was extracted with 5x200 mL CH2CI2. The pooling of these extracts and removal of the solvent under vacuum gave a residue of 85.5 g of the product 3-ethoxy-4-methoxybenzaldehyde, with a mp of 52-53 °C. 

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