8-ETHYNYLQUINOLINE

Synthesis

869208-50-4

103987-81-1

A 300 mL two-neck flask was charged with 8.5 g (40 mmol) of dimethylhydroxymethyl-8-quinoline acetylene and 1.0 g (45 mmol) of sodium hydroxide (manufactured by KISHIDA CHEMICAL CO., Ltd., 0.7 mm particles, 98%). The unit was equipped with a reflux condenser and the air inside the flask was replaced with argon. 200 mL of toluene was added and the mixture was refluxed at 120 °C for 0.5 h. The reaction was carried out at 120 °C. Upon completion of the reaction, diethyl ether was added to the reaction mixture and the organic layer was washed with saturated aqueous ammonium chloride solution and subsequently dried with magnesium sulfate. After removing the solvent by distillation under reduced pressure, 250 mL of hexane was added to the residue and the mixture was heated to 70 °C. After filtration to remove insoluble material, the filtrate was cooled to -78 °C to precipitate the target product 8-ynylquinoline. The precipitate was collected by filtration and washed with cold hexane (-78 °C; 100 mL) and finally dried under reduced pressure to give 4.9 g of yellow-white solid product in 80% yield. The structure of the product was determined by 1H-NMR (300 MHz, CDCl3) δ: 3.60 (s, 1H), 7.32-7.53 (m, 2H), 7.83 (dd, 1H), 7.93 (dd, 1H), 8.17 (dd, 1H), 9.06-9.08 (m, 1H) and mass spectra (EI-MS (M/Z): 153 (M+-1) , CI-MS (M/Z): 154 (MH+) confirmed.

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