Abstract
The properties of the microenvironments of methyl orange, ethyl orange, and butyl orange solubilized in alkyltrimethylammonium bromide (alkyl-TAB, involving alkyl group such as decyl, dodecyl, tetradecyl, hexadecyl or octadecyl group) micellar solutions have been examined by means of spectroscopic procedures. The absorption maximum frequencies (vmax) of methyl orange, ethyl orange, and butyl orange in the mixtures of ethanol-water, dioxane-water, and acetone-water have been successfully correlated with the solvent polarity parameter, Grunwald-Winstein's Y value, respectively. By comparing the Y values obtained from vmax of the dye in micellar solution with those in the solvent mixtures, the properties of the microenvironments of the dye is discussed. Butyl orange, the most hydrophobic dye of three, is supposed to be solubilized in hydrophobic environments of the micellar solutions of decyl-, dodecyl-, and tetradecyl-TAB, but in relatively less hydrophobic environments of hexadecyl-, and octadecyl-TAB. Ethyl orange and methyl orange are supposed to be solubilized in relatively less hydrophobic environments of micellar solutions of all the alkyl-TAB, respectively. The microenvironments of the dyes solubilized in alkyl-TAB micellar solutions are considered to be primarily dependent on the alkyl group of the dye and secondly dependent on the length of alkyl chain of alkyl-TAB.
