Effect of Cationic Micelles of Cetyltrimethylammonium Bromide on Protonation Equilibria of Salicylic Acid Derivatives

Abstract

To gain more information about the effect of surfactant on salicylic acid derivatives, the stoichiometric protonation constants of 5-Sulphosalicylic acid and 5-Hydroxysalicylic acid in 0.0%-2.5% (w/v) cetyltrimethylammonium bromide (CTAB) -water mixtures were determined at an ionic strength of 0.16 mol dm -3 and at 303 K. A potentiometric method was used and the calculation of constants was carried out using the computer program MINIQUAD75. These protonation constants values have been found to shift in micellar media as compared to those in pure water. The differences in the values have been attributed to the solvent properties of the interfacial and bulk phases involving contribution from the micellar surface potential in the case of charged micelles. The trend of log values of step-wise protonation constants with mole fraction of the medium have been explained based on specific solute-solvent interactions. In this study Distributions of species, percentage of species composition, protonation equilibria and effect of influential parameters on the protonation were also discussed.

Potentiometric studies of complex equlibria of CaII, MgII and ZnII with 5-sulphosalicylic acid in cationic micelles of CTAB

“…All the Potentiometric titrations were performed in various composition of Cetyltrimethylammonium bromide ranging from 0.0 to 2.5 % w/v at 303.0 ± 0.1 K with marinating ionic strength using NaCl. Correction factor [16, 17] is applied to account the effect of variation in the dissolved CO 2 , asymmetry potential, activity coefficient, liquid junction potential and sodium ion error due to use of glass electrode.…”

“…MINIQUAD75 exploit the advantage of the constrained least-squares method in the initial refinement and reliable convergence of Marquardt algorithm. The correction factor and the protonation [22] constants of 5-sulphosalicylic acid were predetermined at the time of calculation of stability constants of binary metal-ligand complexes. The alteration of stability of complex species with the composition of the cationic surfactant was investigated on electrostatic grounds and interactions between solute and solvent.…”

AN ELECTROMETRIC METHOD FOR THE DETERMINATION OF IMPACT OF DMSO-WATER MIXTURES ON pKa VALUES OF SALICYLIC ACID DERIVATIVES

“…Salicylic acid derivatives like 5-SSA and 5-HSA have numerous applications in drug designing [6][7][8][9]. The dielectric constant is a macroscopic property which plays a significant role in the solution properties of the reaction medium.…”

“…The binary mixtures of dipolar aprotic and protic solvents have current interest in biological, chemical, pharmaceutical, technological and laboratory applications because mixed solvents manifest physicochemical properties as compared to those of pure constituents of the mixture amongst the physicochemical properties, dielectric constant of the mixed solvents, which is sensitive to molecular interactions specially H-bond formation, enhances or controls most of the applications, and hence precise the dielectric characterization is important. The study of chemical speciation plays a very important role to understand nutrition, human biology and toxicology, which will also helpful to understand the nature of an element in the sample [11]. One of the most important parameter in pharmaceutical is acid dissociation constants, ionization of functional groups with respective to pH; they are very useful in understanding the properties of new drug substances.…”

Dynamics of CTAB micelle mediated reaction of fuchsin degradation in alkaline medium

“…Cetyltrimethylammonium bromide (CTAB) is a cationic surfactant which influences a lot of reactions by shifting the acid-base equilibria [2]. CTAB has been reported to catalyze the reaction between dipeptide glycyl-alanine and ninhydrin [3] and the catalytic role of CTAB in chemical reactions have been attributed to the hydrophobic/electrostatic interactions [4].…”