title: Separation and acid equilibria of xylenol orange and semi-xylenol orange.
abstract: A mixture of Xylenol Orange (XO) and Semi-Xylenol Orange (SXO) was chromatographed on a cellulose column and ion-exchanged with Diaion SK-1 resin. XO and SXO in the acidic forms were titrated with sodium hydroxide to determine the basicities and the acid formation constants. The absorption spectra of XO and SXO were measured over a wide pH range, and were used for the calculation of acid formation constants, molar absorptivities, and the effect of ionic strength on the activity of XO. The purity of a commercial XO was measured by absorption spectroscopy, and it was found that the sample contained 36.3% of XO and 17.2% of SXO. Pure XO and SXO form a 1:2 and a 1:1 complex respectively with Zn(II). On the basis of these data the ionic structure of XO and SXO have been compared with those of Cresol Red and iminodiacetic acid, and discussed.
authors.affiliation: Department of Chemical Technology, Faculty of Engineering, Yamaguchi University, Tokiwadai, Ube, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Murakami
authors.forename: T
authors.initials: T
authors.lastname: Yoshino
authors.forename: S
authors.initials: S
authors.lastname: Harasawa