CXCII.—The absorption spectra of simple aliphatic substances in solutions, vapours, and thin films. Part I. Saturated aldehydes and ketones
Journal of the Chemical Society Transactions
IN a recent paper on the absorption spectra of some substances containing two benzene nuclei (this vol., p. 1514), the authors draw some conclusions as to the mutual effect on one another of two oscillation centres in a molecule. In order to study this point further, it was decided to investigate substances of a simple nature containing one oscillating centre, or two similar centres, so as to obtain evidence which might make it possible to build up the absorption spectrum of a substance from
... a substance from the known types of oscillation of the various oscillation centres composing it. The aim of this paper is to describe the results obtained from a comparative study of various aliphatic aldehydes and ketones in order to determine in what direction, and how far, their absorption of light is affected when such substances are in solution, as vapours and in thin films. The substances examined were: Formaldehyde, acetaldehyde, propionaldehyde, chloral, chloral hydrate, glyoxal, acetone, chloroacetone, methyl ethyl ketone, diethyl ketone, acetylacetone, and diacetyl. The experimental methods have been described before. The sources of light were the cadmium spark; the uranium-molybdenum spark; the copper spark; also an acetylene flame was used in the investigation of the least refrangible absorption bands of the vapours of glyoxal and diacetyl. Stewart and Baly (Trans., 1906, 89, 492) have studied solutions of various methyl ketones, two of which observations have been repeated by the authors to compare with the vapours. Solutions. FormaZdehiyde.-Efforts were made to obtain solutions of the substance in alcohol and in ether by passing the vapour into the solvent. It was found that it rapidly polymerised in ether, and there was no selective absorption; in alcohol it appeared gradually to combine with the solvent, and anomalous results were obtained. There was, however, a considerable amount of general absorption ; for, through a thickness of 90 mm. the rays were absorbed in an ethereal solution from about h 2680. In another N/2-alcoholic solution, the rays were absorbed from about ~2 8 0 0 through a thickness of 38 mm.