135754-88-0Relevant articles and documents
Substitution reactions of benzethonium chloride with ion associates of bromocresol green - quinine and bromophenol blue - quinine in dichlormethane
Gainza, Alberto Hernandez,Konyeaso, Roy Ikemefula
, p. 937 - 944 (2007/10/02)
An excess concentration of base quinine (Q) reacts with a sulphonphthalein diacidic dye XH2, (bromocresol green, BCGH2, or bromophenol blue, BPBH2) in dichlormethane solution to form an ion associate (X(2-)(QH21+)2) of stoichiometry 1:2 (dye:amine).Benzethonium chloride (CIB) reacts with the 1:2 ion associate to form an ion associate (QH1+,X2-,B1+) and quinine hydrochloride ClQH(1+).This substitution reaction is a chemical equilibrium with formation constants of 1.50+/-0.67, 1.64+/-0.54, 1.07+/-0.29, 1.04+/-0.20, and 0.84+/-0.26 for BCG and 1.86+/-0.59, 1.47+/-0.23, 1.40+/-0.65, 1.13+/-0.37, and 1.11+/-0.27 for BPB at 283.16, 288.16, 293.16, 298.16, and 303.16 K respectively.The thermodynamic parameters determined by van't Hoff's equation are ΔH0 = -21.766+/-7.482 kJmol-1, ΔS0 = -73+/-51 Jmol-1K-1, and ΔG0 = -1.134+/-0.972 kJmol-1 for BCG and ΔH0 = -18.678+/-7.482 kJmol-1, ΔS0 = -61+/-26 Jmol-1K-1, ΔG0 = -0.916+/-0.401 kJmol-1 for BPB (ΔG0 at 293.16K; and ΔH0 and ΔS0 determined in the range 283-303K). Key words: bromocresol green-quinine-benzetonium, ion associate mixture, bromophenol blue-quinine-benzethonium, equilibrium constants, thermodynamic parameters.