Rotatory Dispersion of Aliphatic Aldehydes

Abstract

Rotatory dispersion curves of configurationally related aldehydes of the type $$\begin{array}{c}\mathrm{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}}{\mathrm{CH}}_3\\ \mathrm{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}|}\\ \mathrm{H}–\mathrm{C}\mathrm{–(}{\mathrm{CH}}_2{)}_n\mathrm{C}\begin{array}{c}=\mathrm{O}\\ {–}_{\mathrm{H}}\end{array}\\ \mathrm{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}|}\\ \mathrm{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}}{\mathrm{C}}_2{\mathrm{H}}_5\end{array}$$ (n being equal to 0, 1, 2, or 3) have been determined in the visible and the ultraviolet regions of the spectrum. Their analysis has shown first, that the band of the aldehydic group at λ2950 is rotatory active and that the sign of its contribution in the first member (n=0) is opposite to that of the higher members and second, that the magnitude of that contribution varies periodically with the number of carbon atoms located between the aldehydic group and the asymmetric carbon atom.