The Electronic Spectra of Unsubstituted Mono‐ to Pentaacetylene in the Gas Phase and in Solution in the Range 1100 to 4000 Å

The electronic spectra of the title compounds I (n), n = 1 to 5, were recorded under standard conditions for quantitative comparison. Spectra of I(1) to I(4) in the gas phase and of I(2) to I(5) in nonpolar solutions are presented in a computer plotted form, and wave length maxima and intensities are listed. Tentative assignments of the medium‐intensity, first transition (A band) and the ultrahigh‐intensity, second transition (B band) are given. Finally, spectra of I(2) to I(5) recorded at − 150° are presented and discussed (A band). The syntheses of I(3) to I(5) are given in detail.