Rotatory dispersion in the amine series III-The absorption spectra of diamines

Abstract

In view of the striking effect on the rotatory powers of optically active amines which occur when the lone-pair of electrons on the amino-nitrogen atom is saturated, as described in the two preceding papers, it was of importance to investigate the corresponding changes which are indicated in the absorption spectra the corresponding changes which are indicated in the absorption spectra of simple amino compounds. Absorption spectra are therefore now recorded for hydrazine and for ethylene-diamine, and the effect on these spectra of varying the acid concentration of the solutions has been measured. No previous measurements of the absorption of hydrazine in solution have been recorded, but sunao and Imanishi (1931) observed a series of bands between 2400 and 2200 A in the vapour. Ethylene-diamine has been examined by Bielecki and Henri (1913), and Castille and Ruppol (1928) have investigated its hydrochloride. The latter authors reported a weak absorption band in aqueous solutions of the salt (ϵ max = 0·4 at 2631 A), but this observation is not confirmed by the present results. It may be attributed to the presence of an impurity, since, in the first series band (ϵ max = 2 at 2631 A) was also seen, but after recrystallization of the salt it disappeared completely.