The synthetic procedure was optimized based on literature reports. 1,8-Dihydroxynaphthalene (200 mg, 1.25 mmol) was dissolved in 10 mL of acetone and potassium carbonate (1.73 g, 12.5 mmol) and dimethyl sulfate (1.19 mL, 12.5 mmol) were added sequentially. The resulting inhomogeneous mixture was heated to 70 °C and stirred at this temperature for 24 hours. After completion of the reaction, the mixture was cooled to room temperature and the reaction was quenched with deionized water (15 mL). The aqueous phase was extracted with dichloromethane (3 x 10 mL). The organic phases were combined, dried with anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure to give pure 1,8-dimethoxynaphthalene (216 mg, 92% yield) as a light yellow solid. All spectral data were in agreement with literature reports. Thin layer chromatography (TLC) Rf = 0.46 (ethyl acetate:hexane = 1:9); 1H NMR (400 MHz, CDCl3) δ 7.41 (2H, dd, J = 8.2, 1.4 Hz), 7.39-7.35 (2H, m), 6.86 (2H, dd, J = 7.4, 1.2 Hz), 3.99 (6H, s); 13C NMR (100 MHz, CDCl3) δ 157.2, 137.5, 126.5, 121.0, 117.8, 106.3, 56.6; Fourier Transform Infrared Spectroscopy (FTIR, ATR, solid) 3001, 2956, 2836, 1580, 1460, 1427, 1386, 1348, 1273, 1237 cm-1; High Resolution Mass Spectrometry (HRMS, APCI+) calculated value C12H13O2 [M + H]+: 189.0911, measured value: 189.0917.
