Synthesis
General procedure for the synthesis of 4-hydroxy-6-chloroquinoline from 6-chloro-4-oxo-2,3-dihydroquinoline: 6-chloro-4-oxo-2,3-dihydroquinoline (0.01 mol) was placed in a 25 mL reaction flask, and 15 mL of acetonitrile and acetic acid (0.01 mol) were added and stirred for 20 min. Subsequently, hydrogen peroxide (0.03 mol) was added slowly and the reaction was stirred at 65 °C. The progress of the reaction was monitored by thin layer chromatography (TLC) and the reaction was terminated after 7 hours. After the reaction solution was cooled to room temperature, it was poured into 50 mL of water, stirred and filtered to obtain the crude product of 4-hydroxy-6-chloroquinoline. The crude product was purified by silica gel column chromatography (silica gel 100-200 mesh, eluent was petroleum ether:ethyl acetate=1:4), and the target component was collected and concentrated to obtain the pure product. The product yield was 88% and purity was 96%.
References
[1] Patent: CN108794396, 2018, A. Location in patent: Paragraph 0017
[2] Journal of the American Chemical Society, 1949, vol. 71, p. 1906,1910