General procedure for the synthesis of vanillyl ethyl ether from vanillin and triethyl orthoformate: 3.04 g (20.0 mmol) of vanillin, 5.93 g (40.0 mmol) of triethyl orthoformate, 15.0 mg of p-toluenesulphonic acid monohydrate, and 15.0 mg 5% palladium-carbon catalyst were added to a 100 ml autoclave (equipped with an inner tube). After displacing the internal gas of the system under nitrogen protection, it was replaced with hydrogen and filled with hydrogen at 3.0 MPa. The autoclave temperature was controlled at 130°C and the reaction was continuously stirred for 1 hour. Upon completion of the reaction, the reaction mixture was cooled and the hydrogen pressure was subsequently released. The palladium carbon catalyst was removed by filtration and the unreacted triethyl orthoformate was recovered by distillation under reduced pressure, resulting in 3.60 g of vanillyl ethyl ether (97.4% purity and 96.2% yield as determined by internal standard method). The structure of the product was confirmed by 1H-NMR (CDCl3): δ=1.37 (3H, t), 3.42 (1H, q), 3.86 (3H, s), 4.44 (2H, s), 5.92 (1H, s), 6.88 (3H, m).
