Kinetics of malachite green fading in alcohol–water binary mixtures

Abstract

The rate constant of alkaline fading of malachite green (MG + ) was studied in alcohol-water binary mixtures. This reaction was studied under pseudo-first-order conditions at 283-303 K. It was observed that the reaction rate constants were increased in the presence of different weight percentages of methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, 1,2-propanediol, and glycerol (up to 19.3%). In aqueous glycerol solutions higher than 19.3%, the rate constant of reaction slightly decreases, which is due to high viscosity values of solvent mixtures. The fundamental rate constants of MG + fading in these solutions were obtained by using the SESMORTAC model. Owing to the charged character of activated complex, with an increase in the weight percentage of the used cosolvents or temperature, k 2 values change according to the trend of hydroxide ion nucleophilic parameter values. Also, using MG + solvatochromism, a simple test, called MAGUS, is introduced for measuring the glycerol concentration in its aqueous solutions. C 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: [508][509][510][511][512][513][514][515][516][517][518] 2010

Kinetics of brilliant green fading in the presence of TX-100, DTAB and SDS

“…= group of MG ? and results in a decrease in K tot and thus the fading rate constant values of BG/DTAB compound at 283-303 K (Tables 4, 5) compared to those of MG/DTAB compound [16].…”

“…in water are 7.97, 20.93 and 52.05 M -1 min -1 at 283, 293 and 303 K, whereas the fading rate constants of MG ? in water are 18.89, 46.98 and 118.60 M -1 min -1 at 283, 293 and 303 K, respectively [16]. As we know, the electron-releasing inductive effect of the ethyl groups of BG ?…”

“…= group of MG ? and results in an increase in K tot values of BG/SDS at 283-303 K, Table 7, compared to those of MG/SDS [16] and thus the fading rate constants of BG/SDS, Table 6, are less than those of MG/SDS [16]. This test was carried out to verify the existence of regions and is called Pardis test [15].…”

“…[14]. In continuation of our earlier works [15,16], we studied the BG ? alkaline fading in the presence of different concentrations of TX-100, DTAB and SDS at 283-303 K. BG ?…”

“…alkaline fading in the presence of different concentrations of TX-100, DTAB and SDS at 283-303 K. BG ? fading is a one-step reaction and kinetics of these kinds of reactions in the presence of surfactants can be studied using cooperativity and classical models [15,16]. Also, in this work, substituent effects of ethyl groups of BG ?…”