41—THE EFFECTS OF A POLYETHYLENE OXIDE CONDENSATE AND SOME POLYETHYLENE GLYCOLS ON THE ABSORPTION SPECTRA OF CERTAIN AZO DYES

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Abstract
The presence of Dispersol A, a polyethylene oxide condensate, in an aqueous 1O mg./l. Benzopurpurine 4B solution has a considerable effect upon the absorption spectrum of the dye. The spectral effect is similar to that of pyridine, and is independent of the Dispersol A concentration over the range 0·5 to 10 per cent. The absorption spectra of the dye (10 mg./l.) in solutions containing less than 0·5 per cent. Dispersol A depend on the Dispersol A concentration, and have an isosbestic point. One per cent. Dispersol A has also a considerable effect on the absorption spectra of other azo dyes, the spectral effect with each dye being similar to that of pyridine. It is suggested that these dyes can combine with the polyethylene oxide condensate to form complexes. The presence of i per cent, of a polyethylene glycol in an aqueous Benzopurpurine 4B solution has an effect similar to that of Dispersol A on the absorption spectrum of the dye. The effect, however, is greater the greater the mean molecular weight of the polyethylene glycol. With any one polyethylene glycol, the presence of 5 per cent, polyethylene glycol in the aqueous dye solution has a greater effect than has 1 per cent, on the spectrum of the dye. Similar results are obtained with the other azo dyes, meta-Benzopurpurine 4B and Direct Fast Orange SE. With each of these dyes the spectral effect of 1 per cent, of the polyethylene glycol of highest molecular weight is less than the spectral effect of 1 per cent. Dispersol A. Moreover the spectral effect of Dispersol A, unlike that of the glycol, reaches its maximum at a very low concentration. It is therefore suggested that although the polyethylene glycol may form a complex with the dye, the dye-glycol complex is less stable than the dye-condensate complex. It is further suggested that the difference in stability of the complexes is due to the presence of micelles in the condensate, but not in the glycol, solution.

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