Synthesis,spectral-luminescence,and acid-base properties of 3-halo-7-aminocoumarins

The reactions of substituted coumarins with a variety of halogenating agents, leading to the formation of the corresponding 3-chloro-, 3-bromo-, and 3-iodo-7-aminocoumarins, have been studied. It has also been shown, based on the results of studies of the spectral-luminescence and acid-base characteristics of these 3-halo-7-aminocoumarins, that their basicity increases as the electron-donating nature of the substituent in the 4-position increases, and is also greater, as expected, for 3-iodo- and 3-chloro derivatives than for 3-bromo derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1600–1609, December, 1990.