ISSN:
0894-3230
Keywords:
Organic Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The participation of the carboxylate group in the ionization of Rhodamine B leucocyanide was studied in an aqueous solution of poly(vinylbenzyltrimethylammonium chloride) (PVBTA) or cetyltrimethylammonium bromide (CTAB) at constant temperature and pH 8. The experimental rate constant (kexp) decreases with increasing PVBTA concentration. The results are interpreted in terms of the binding of the ionized form of Rhodamine B leucocyanide (RBCN-) to a single class of completely independent binding sites on the PVBTA. From this model, a value of 1.09 × 106 l mol-1 was obtained for the binding constant. The effect of CTAB is different from that obtained with PVBTA. After a region in which there are large changes in kexp with the CTAB concentration, this constant reaches a zone where its value is independent of the surfactant concentration. The decrease in kexp in the first zone was explained in terms of an ionic association between RBCN- and the cationic heads. In the second zone, it was assumed that a micellar effect operates on the ionization kinetics. In a similar form, the esterification of the carboxylate group leads to a slower ionization rate.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/poc.610050907
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