Synthesis
A dioxane (20 mL) solution of anthracene (1.78 g, 10 mmol), anhydrous ZnCl2 (1.64 g, 12 mmol), and paraformaldehyde (1.50 g, 50 mmol) was added sequentially to a reactor vessel equipped with a stirrer. A concentrated aqueous hydrochloric acid solution (40 mL) was added slowly and dropwise with stirring, and the reaction temperature was controlled to be below 50 °C. The reaction mixture was stirred at room temperature until homogeneous and then heated to a mild reflux condition and kept for 3 hours. After completion of the reaction, the mixture was allowed to stand at room temperature for 16 hours to complete crystallization. The resulting fine grained solid was separated by diafiltration and washed sequentially with deionized water and dioxane. The crude product was purified by recrystallization with toluene to give 1.8 g of light yellow solid product in 64.1% yield. The structure of the product was confirmed by 1H NMR (500 MHz, CDCl3): δ 8.40 (m, 4H), 7.62 (m, 4H), 5.61 ppm (s, 4H).
References
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