Hydrochloric Acid → 6,7-Difluoro-2-methylquinoline

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Reaction Steps

25.0 g of 3,4-difluoroaniline are dissolved in 120 of 2-butanol. 50 ml of a saturated solution of hydrogen chloride in 2-butanol are added slowly and afterwards 47.6 g (0.1936 mol) of p-chloranil are also added. With a good stirring and at reflux temperature (100-110° C.) a solution of 19.4 ml (0.236 mol) of crotonaldehyde in 45 ml of butan-2-ol is dropped slowly (ca. 2 hr). The whole is refluxed for two additional hours and then evaporated to dryness. The residue is taken with excess THF and is filtered and washed thoroughly with THF until the filtering appears to be uncoloured. The solid thus obtained is solved in water, filtered from some solid impurities and washed with ethyl ether. The aqueous layer is made slightly alkaline with 2N NaOH solution and then extracted with diethyl ether. The ethereal layer is dried and treated with a little decolourising charcoal. After evaporation a white solid is obtained (22.7 g, 65%).

Provenance & Evidence