Titration of diprotic acids in alcohols and intramolecular hydrogen bonding in monoanions with emphasis on isopropanol and tert-butanol

A conductometric study of dissociation of picric acid in 2-methoxyethanol and 1,2-ethanediol from −10 to 80 °C

“…Although alcohols have received much attention as solvents for acid-base determinations (1,2) there are not many studies on the use of 2-methoxyethanol (hereafter abbreviated Gliem) and 1,2-ethanediol (Gliet) as solvents in acid-base titrations and on the determination of dissociation constants of weak acids. Our previous works (3)(4)(5)(6) have reported on the feasibility of conductometric titrations of monoprotic and diprotic acids, phenols and aromatic nitroderivatives in the above solvents using N,N1-diphenylguanidine as titrant.…”

“…The value for K,,, calculated to best fit eq. [2] is quite in good agreement both with the results obtained by a method suggested by Harned (10) (K,,, = 2.46 x lop3 at t = 38.4"C) and with those evaluated by a correlation of pK vs. I/€. In fact, knowing the relationship between E and t , the above correlation provides two straight lines (one of negative slope, r = 0.923, and the other of positive slope, r = 0.980) intersecting in a point whose ordinate and abscissa give pK,,, and the temperature of K,,,, respectively (K,,, = 2.61 x lop3, t = 34.3"C).…”

“…= constant; the better fitting of this empirical relation suggests that this unusual behaviour is probably a consequence of the high viscosity of the medium. Tables 3 and 4 report the thermodynamic data calculated by the usual equations from the best fitting equation [2]. Many difficulties and uncertainties are associated with these calculations which derive from the inevitable experimental errors in K values and partly from the calculator's choice of the function which represents the dependance on the temperature.…”

Use of the sulfide minerals pyrite and chalcopyrite as electrochemical sensors in non-aqueous solutions. The potentiometric titration of weak acids in alcohols

“…Although the changes in the potential obtained with TBAH or KOH Figure 4. (a) The effect of the indicator electrode on the shape of the end-point inflexion in the potentiometric titration of benzoic acid in isopropanol using the following titrants: (1) sodium methylate, (2) TBAH, and (3) KOH; (b) the effect of the indicator electrode on the shape of the end-point inflexion in the potentiometric titration of (1-7) stearic acid and (8-10) α-Nitroso-β-naphthol in iso-propanol using the following electrodes: (1), (3), and (8) pyrite; (5), (6), and (9) chalcopyrite; and (2), (4), (7), and (10) glass; and the following titrants: (1), (2), and (5) KOH; and (3), (4), and (6 -10) TBAH; (c) the effect of the indicator electrode on the shape of the end-point inflexion in the potentiometric titration of (1-7) benzoic acid and (8-11) stearic acid in tert-butanol using the following electrodes: (1), (3), (8), and (10) pyrite; (5) and (6) chalcopyrite; and (2), (4), (7), (9), and (11) glass, and the following titrants: (1), (2), (5), (8), and (9) KOH; and (3), (4), (6), (7), (10), and (11) TBAH. a c b and the chalcopyrite sensors are lower than for the pyrite sensor, they are distinctive enough to allow the precise determination of the TEP in the titration of very weak acids.…”

“…Therefore, it is very useful for the titration of weak acids with tetrabutylamonium hydroxide (TBAH) [3] and for differentiating the titration of carboxylic acids and phenol [4][5][6]. Due to its excellent solvent characteristics, fundamental information on acid-base equilibria would be very useful [7][8][9][10][11][12][13]. In this solvent, Fritz and Gainer coulometrically titrated mineral acids, sulfonic acids, carboxylic acids, enols, imides and phenols with electrically generated TBAH [14] and with visual and potentiometric determination of the titration end point (TEP).…”