630-98-8Relevant academic research and scientific papers
Kinetics of fading of some triphenylmethane dyes: Effects of electric charge, substituent, and aqueous binary mixtures of dimethyl sulfoxide and 2-propanol
Samiey,Dalvand
, p. 60 - 70 (2014/01/06)
The rate constants of alkaline fading of a number of triphenylmethane (TPM) dyes including methyl green (ME2+), brilliant green (BG +), fuchsin acid (FA2-), and bromophenol blue (BPB 2-) were obtained in aqueous binary mixtures of 2-propanol (protic solvent) and dimethyl sulfoxide (DMSO) (aprotic solvent) at different temperatures. It was observed that the reaction rate constants of BG+ and ME2+ increased and those of FA2- and BPB2- decreased with an increase in weight percentages of aqueous 2-propanol and DMSO binary mixtures. 2-Propanol and DMSO interact with the used TPM molecules through hydrogen bonding and ion-dipole interaction, respectively, in addition to their hydrophobic interaction with TPM dyes. The fundamental rate constants of a fading reaction in these solutions were obtained by the SESMORTAC model. Also, the effect of electric charge and substituent groups of a number of TPM dyes on their alkaline fading rate was studied.
A study on equilibrium and kinetics of carbocation-to-carbinol conversion for di- and tri- arylmethane dye cations in aqueous solutions: Relative stabilities of dye carbocations and mechanism of dye carbinol formation
Sen Gupta,Mishra,Radha Rani
, p. 703 - 708 (2007/10/03)
Arylmethane dye cations form a structurally interesting set of stable carbocations. A detailed study on rate-equilibria of carbinol formation from two diarylmethane and nine triarylmethane dye carbocations in aqueous solutions has been carried out using spectrophotometric measurements. The conclusions reached are : (i) The stability order found (auramine O>crystal violet = methyl violet > victoria blue R > victoria pure blue BO = ethyl violet > pararosaniline > brilliant green > malachite green > carbocation form of Michler's hydrol > methyl green), seems to be determined by an interplay of dye carbocation / carbinol conformation and stereoelectronic effects of substituents; and (ii) carbinol formation is general base catalysed and occurs by the rate determining attack of a H2O molecule on the dye carbocation centre via two kinetic pathways one mediated by another H2O molecule and the other by a OH ion.
Carbenium ion-carbinol equilibration for basic triarylmethane dyes: Relative reactivities of dyes in aq. solutions
Gupta, Susanta K. Sen,Arvind, Udai
, p. 998 - 1000 (2007/10/02)
Equilibria and kinetics of carbenium ion-to-carbinol base reactions for a set of selected basic triarylmethane dyes in aq. buffer solutions of low ionic strength have been measured spectrophotometrically.Relative reactivities of the dyes towards nucleophilic attack by hydroxide ion, on the basis of both equilibrium constant and forward rate constant of the reaction, have been found to follow the same order: malachite green (MG)> brillant green (BG)>> Victoria pure blue BO(VB)> methyl violet (MV) = crystal violet (CV)> ethyl vioet (EV).A fairly good correlation between elec trophilicities of the dyes and ?R+ parameters of their 4-alkylamino substituents has been obtained
Equilibrium and Kinetic Studies on the Formation of Triphenylmethanols from Triphenylmethane Dyes
Hagiwara, Takuyuki,Motomizu, Shoji
, p. 390 - 397 (2007/10/02)
For five kinds of triphenylmethane dyes, the rate constants of hydration and dehydration reactions, and equilibrium constants in an aqueous solution were measured by a stopped-flow method.An increase in the number of dialkylamino groups caused a decrease in the rates and the equilibrium constants of the hydration, and the more the electron-donating effect of the dialkylamino groups, the slower the hydration rate became.The more protonated quinonoids were easily converted to the corresponding alcohols.On the basis of the equilibrium constants, Malachite Green was ascertained to be the best reagent of the five dyes for ion association with heteropolyacids in an aqueous medium.
Effect of Pressure on the Rate of Alkaline Fading of Triphenylmethane Dyes in Cationic Micelles
Taniguchi, Yoshihiro,Iguchi, Akira
, p. 6782 - 6786 (2007/10/02)
The rates of alkaline fading of triphenylmethane dyes in cationic micelles have been measured at pressures up to about 2 kbar and at 25 deg C in 0.1 M Tris buffer solution.These rates follow the kinetics of the Michaelis-Menten type.The volume changes for the incorporation of dyes in the micellar phase are 14-15 cm3/mol for ethyl violet and brilliant green and 3-4 cm3/mol for crystal violet and malachite green.It was confirmed that these differences are due to the hydrophobicity of dyes.The activation volumes for the fading reaction in micellar phases are positive except in the case of the crystal violet-cetyltrimethylammonium bromide micellar system.However, the activation volumes in nonmicellar aqueous solutions are negative.The differences of the activation volumes between micellar and nonmicellar systems are discussed from the point of view of the general base catalysis, which contains both the water and hydroxide ion pathways.It was clear that micelles change the water control into hydroxide ion control.
The Hydrolysis of Brilliant Green and Some Derivatives. Part 2. The Kinetics of the Hydrolysis of 3- and 4-Substituted Derivatives of Brilliant Green
Fox, Brenda M.,Hepworth, John D.,Mason, Donald,Hallas, Geoffrey
, p. 987 - 992 (2007/10/02)
Rate constants have been measured for the reactions of hydroxide ion with the following derivatives of Brilliant Green in aqueous solution: 3-X (X = Cl, OMe, CF3, Me, NO2, NMe2, or OH); 4-X (X = Cl, OMe, CF3, Me, NO2, or NMe2).The substituents affect the rate of hydrolysis to an extent linearly related to the appropriate Hammett substituent constant.Thermodynamic parameters ΔH(excit.) and ΔS(excit.) have been obtained for each dye and the reaction is shown to be under entropy control.
