SOME NITRO DERIVATIVES OF 2,4- AND 2,6-DIMETHYLQUINOLINE¹

Abstract

The high antimalarial activity of pamaquine (Plasmochin) suggested that other 8-aminoquinoline drugs be prepared for evaluation. The present paper describes some experimental observations which arose from the preparation of 2,4-and 2,6-dimethyl-8-nitroquinoline as intermediates for this purpose.According to Roberts and Turner (1), 2,4-dimethylquinoline may be nitrated readily at low temperatures to produce a compound melting at 119°. This was assigned the structure of the 8-nitro derivative, since on reduction and diazotization it could be converted to 8-chloro-2,4-dimethylquinoline, identical with an authentic sample. Roberts and Turner (1) further reported the Baeyer synthesis on o-and p-nitroaniline to yield products, m.p. 145-147°and 159-162°, respectively, but stated that the former could not have been the expected 2,4dimethyl-8-nitroquinoline.When the nitration of 2,4-dimethylquinoline was carried out according to the directions of Roberts and Turner (1), a good yield of crude nitro derivatives was obtained. A small sample recrystallized from alcohol had the melting point (120°) reported by Roberts and Turner. However, a similar recrystallization of the bulk of the nitroquinoline yielded a material melting at 110-138°. Careful fractionation by dilute sulfuric acid extraction followed by recrystallization gave two pure dimethylnitroquinolines, m.p. 149-150°and 163-164°. These