Integral intensities of the absorption bands of the skeletal vibrations of the heteroaromatic ring in the IR spectra of the furanoquinoline alkaloids

1. The integral intensities of the bands of the skeletal vibrations of the heteroaromatic ring in the 1480–1630-cm⁻¹ region of eight furanoquinoline alkaloids have been measured. 2. A connection has been found between the values of ΣA and the structures of the furanoquinoline alkaloids and their derivatives which enables such a series of heteroaromatic compounds to be identified: It has been shown that the introduction of an -OCH₃ group into the γ position of the pyridine nucleus leads to a marked rise (almost twofold) in the value of ΣA;