Quantitative measurements of the absorption of light. I.―The molecular extinctions of the saturated aliphatic ketones

Abstract

The results of an examination of the absorption spectra of some saturated aliphatic ketones in alcoholic were published by Stewart and Baly, and it was shown that there second to be a direct connection between the persistence of the absorption band and the chemical reactivity of the ketone in each case as measured by the rate of the formation of its oxime or sodium bisulphite compound. Since the date of that paper the technique of absorption methods has been considerably improved, and it appeared worth while to investigate the absorptive power of the same ketones with the more efficient methods now available. It was found at once that there is a very considerable difference in the position of the absorption band according to whether the ketone is observed in the pure state or in solution. As is well known, the effect of the solvent generally is to shift the absorption maximum towards the longer wave-lengths, this shift being as much as 100 Å. U. in the case of acetone and its aqueous solution. Moreover, it was also found that the shift varies irregularly from ketone to ketone, and it is therefore obvious that in order to compare the ketone amongst themselves it is necessary to deal with the pure ketones and not their solutions.