The conductometric titration of carboxylic and phenolic acids in non-aqueous solutions

Meurs, N. van; Dahmen, E.A.M.F.

doi:10.1016/0003-2670(59)80216-6

Cited by 13 publications

(5 citation statements)

References 7 publications

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“…4-Nitrophenol in Gliem (Figure 3) shows the evidence of two breaks at base/acid molar ratio 1:1 and 1:2 overall at 25 and 50 °C, while any difficulty may be present at the other temperatures (smooth curves as above). Other authors (9,10) have observed for similar phenols a behavior that is analogous for the presence of two equivalent points in the conductometric titration curves, but substantially different: in fact, the break points were at base-acid molar ratios 1:2 and 1:1 and the first was attributed to the formation of a complex anion, phenol-phenolate, stabilized by hydrogen bonding In alcoholic solutions and at low concentrations, which are our experimental conditions, the formation of the above complex is very unlikely. In our titrations the 2:1 break should arise from a donor-acceptor adduct in which the nitro group can be involved in the delocalization of the negative charge of the anion titration curves beyond the first equivalent point may appear as smooth curves, that we have approximated as two straight lines with quite satisfactory correlation coefficients (ranging between 0.986 and 0.999).…”

Section: Resultsmentioning

confidence: 99%

“…Recently, a numerical solution has been published, which permits the accurate prediction of the elution band profile of a pure compound when its equilibrium isotherm in the chromatographic system used is known ( 9). An experimental demonstration of the validity of this numerical solution has been published (10). The difficulty in applying this solution is that the exact equilibrium isotherm should be known.…”

Section: Discussionmentioning

confidence: 99%

“…The elution profile depends very strongly on this isotherm, and it is very sensitive to small changes of the numerical values of its constants. Moreover, the determination of equilibrium isotherms, even with the simple, rather straightforward, and fast ECP method, is time-consuming (10).…”

Section: Discussionmentioning

confidence: 99%

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Effects of temperature and solvent composition on conductometric titrations in nonaqueous mixed solvents

Franchini¹,

Preti²,

Tassi³

et al. 1988

Anal. Chem.

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The effects of temperature and composition of solvent mixtures on conductometric tltratbns have been lnvestlgated for the solvent system 2methoxyethand/ethane-l,2dloi. Good analytical results were obtained for a series of monocarboxylic aiiphatk and ammatk aclds and phenols by uslng 0.10 M N,N'-dlphenylguanMlne as standard titrant. Conductance titration curves, performed at -10, 25, 50, and 75 O C in the abovementioned pure solvents and in their four binary mixtures, are plesented and discussed. The peculiar behavlor of pick ackl in the lnvestlgated solvent system is emphasized in the discusslon. The titrimetric determination of weak acids or bases inin which a ion-pair-formation step is followed by a dissociation equilibrium, is one of the most powerful tools in analytical chemistry because it can provide information unavailable by other techniques, such as about the formation of ion pairing or other ion aggregation phenomena at the various points of the titration ( I , 2). Ion pairiig can influence the reaction rates and the equilibria for many solute-solvent systems at low concentrations, and consequently, it is an important factor in selecting solvents and reagents for analytical purposes (3).Conductance measurements are particularly effective in the determination of ion-pair formation constants and ion mobilities and remain a very useful technique especially for acquiring information about nonaqueous solutions. Furthermore, if used for titrations, a careful selection of the solvent system makes possible a differentiation of single functions present either in different molecular units or in the same molecule.Alcohols have received good attention as solvents for acid-base determinations (1,2) but not many conductometric studies appeared in the past about alcoholic solvent mixtures, only in the last years are they becoming more common (3). In our previous works (4-7) studies were reported on the feasibility of conductometric titrations of monoprotic and diprotic acids, phenols, and aromatic nitroderivatives in 2-methoxyethanol (hereafter abbreviated Gliem) and ethane-1,2-diol (Gliet) as solvents, using N,"-diphenylguanidine (DPG) as base titrant dissolved in the above media. The choice of the two solvents was suggested by considering that they are good solvents for the titration of acidic compounds, that the most common organic acids are soluble enough to do excellent titrimetric work, and that they are completely miscible. DPG was chosen because it can be conveniently recrystallized, it is a stable standard material, quite soluble in nonaqueous media, and it has a high equivalent weight; furthermore, DPG shows a low conductance in the solvents used, as revealed by the curvature in a X vs c1I2 plot. The results indicated also the possibility of performing differential titrations of acid mixtures in cases where such determinations are very difficult, if not impossible, in aqueous solutions. nonaqueous solvents of the typeThe subsequent developments of this research should aid in the investigation of the influenc...

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Effects of temperature and solvent composition on conductometric titrations in nonaqueous mixed solvents

Franchini¹,

Preti²,

Tassi³

et al. 1988

Anal. Chem.

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“…In prior studies of ZnL 1–4 (MeOH), p K a,MeOH was measured using titrations with a pH probe . However, this method has been shown to give poor calibration and inconsistent results for nonaqueous solvents with low-dielectric constants, − such as methanol . For that reason, p K a,MeOH values were determined for ZnL 1–8 (MeOH) using the spectrophotometric technique described by Polster and Lachmann .…”

Section: Resultsmentioning

confidence: 99%

Enhancing CO₂ Capture via Metal–Ligand Cooperativity: Tuning Ligand Basicity and Zn(II) Lewis Acidity

Phipps,

Zirilli,

Duff

et al. 2024

Inorg. Chem.

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A series of thiosemicarbazonato-hydrazinatopyridine zinc(II) complexes were evaluated as direct air CO 2 capture agents. The complexes sequester CO 2 in a methanol solution as a metal-coordinated methylcarbonate. The reaction is reversible upon sparging of solutions with an inert gas (N 2 or Ar). The capture process involves metal−ligand cooperativity with the noncoordinating nitrogen of the hydrazinatopyridine functional group serving as a Brønsted−Lowry base and the zinc acting as a Lewis acid. In this study, the pendent amine of the thiosemicarbazonato group was varied to include 4-phenyl (ZnL 5 ), 4-(trifluoromethyl)phenyl (ZnL 6 ), 4-cyanophenyl (ZnL 7 ), 4-tolyl (ZnL 8 ), and 4naphthyl (ZnL 9 ). Hyperconjugation between the pendent group and the ligand core resulted in modulation of the metal ion acidity, as quantified by ligand exchange equilibrium constants (K 3 = 193−511) and ligand basicity (pK a,MeOH = 11.09−11.94). Variations in electronic structure that decreased ligand basicity were more than offset by increases in Lewis acidity. The equilibrium constant (K 1 ) for CO 2 capture varied from 46300 to 73700. Overall, the value of K 1 was directly related to the relative Lewis acidity of the complexes (K 3 ). Notably, there was an overall inverse relationship between K 1 and the ligand basicity. The results provide insights into ligand design to further improve CO 2 capture.

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“…Sir: Laser desorption mass spectrometry has demonstrated considerable utility for the analysis of nonvolatile, high molecular weight compounds (1)(2)(3)(4), for characterizing molecular adsorbates (5-8), and as a microprobe for molecular and elemental analysis (9)(10)(11). Most of the work reported to date uses a pulsed laser to desorb and ionize the sample in a single step.…”

Section: Correspondencementioning

confidence: 99%

Conductometric titrations of polyprotic acids in nonaqueous mixed solvents. Effects of temperature and composition of the solvent mixture

Franchini¹,

Marchetti²,

Preti³

et al. 1989

Anal. Chem.

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The conductometric titration of carboxylic and phenolic acids in non-aqueous solutions

Cited by 13 publications

References 7 publications

Effects of temperature and solvent composition on conductometric titrations in nonaqueous mixed solvents

Effects of temperature and solvent composition on conductometric titrations in nonaqueous mixed solvents

Enhancing CO₂ Capture via Metal–Ligand Cooperativity: Tuning Ligand Basicity and Zn(II) Lewis Acidity

Conductometric titrations of polyprotic acids in nonaqueous mixed solvents. Effects of temperature and composition of the solvent mixture

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The conductometric titration of carboxylic and phenolic acids in non-aqueous solutions

Cited by 13 publications

References 7 publications

Effects of temperature and solvent composition on conductometric titrations in nonaqueous mixed solvents

Effects of temperature and solvent composition on conductometric titrations in nonaqueous mixed solvents

Enhancing CO2 Capture via Metal–Ligand Cooperativity: Tuning Ligand Basicity and Zn(II) Lewis Acidity

Conductometric titrations of polyprotic acids in nonaqueous mixed solvents. Effects of temperature and composition of the solvent mixture

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Enhancing CO₂ Capture via Metal–Ligand Cooperativity: Tuning Ligand Basicity and Zn(II) Lewis Acidity