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

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

doi:10.1016/s0003-2670(00)88119-2

Cited by 30 publications

(7 citation statements)

References 10 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%

“…theoretical problem, originating with the work of Wilson (1) and De Vault (2), it has not been solved rigorously yet, in spite of many efforts, notably by Glueckauf ( 3 , 4 ) , Guiochon and Jacob (5,6) and Rhee et al (7,8). 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).…”

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%

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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“…Organic acids having a pKa ranging from 4.0 to 5.5 can be titrated with inorganic bases such as sodium hydroxide (at low concentrations), lithium hydroxide (in presence of ammonia) [28], as well as organic bases such as potassium methoxide in pyridine-benzene or tetramethylammonium hydroxide in benzene, with intersection angles as satisfactory as those given by strong acids [29]. Naproxen having one carboxylic acid group with pKa value of 4.15 [2] serves as a suitable candidate for conductometric titration.…”

Section: Resultsmentioning

confidence: 99%

Conductometric determination of naproxen in bulk and pharmaceutical dosage form

Alhazmi

Bratty

2017

Eur. J. Chem.

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This study aimed at the development of simple and cheap conductometric method that can be used for the determination of naproxen in bulk and dosage forms. During the study, naproxen was titrated with sodium hydroxide (Method A) and potassium hydroxide (Method B) and the end points were determined with conductivity cell. Variables affecting the end point determination were also studied in the range of 1-10 mg/mL of naproxen. The proposed methods were validated by precision and recovery studies. The percentage recoveries ranged from 99.15±0.659 and 101.13±0.543 with % RSD of 0.897 and 0.749 with sodium hydroxide and potassium hydroxide, respectively. The methods were effectively applied for the determination of naproxen in tablet dosage form. The methods proposed in this study can be used as substitute for more composite and classy methods used for the determination of naproxen and are highly reproducible as compared to other reported methods. KEYWORDS

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“…In fact the observed maxima in the conductometric titration curves are exactly what would be expected if homoconjugation occurs. The formation of AHA-and its effect on the characteristics of conductometric (12)(13)(14), and potentiometric (14, 15) titration curves have been considered in some recent publications. The large synthetic polynuclear molecule (4) in solution is likely to have intramolecular hydrogen bonds consisting of 2, 3, or 4 O H groups.…”

Section: Resultsmentioning

confidence: 99%

Effects of hydrogen bonding and homoconjugation on the titration curves of a synthetic polynuclear phenolic compound in non-aqueous solvents

Chatterjee¹

1969

Can. J. Chem.

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A straight chain polynuclear phenolic compound containing 9 phenolic nuclei has been synthesized and titrated in several non-aqueous solvents. In some of the solvents, a stepwise neutralization of OH groups in the compound has been observed. Some of the OH groups in the compound have a hyperacid character, and a sharp increase in conductance was observed as these OH groups are neutralized by the base. Some of these features have been discussed in terms of intramolecular hydrogen bonding and homoconjugation between the acid and its anion.

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

Cited by 30 publications

References 10 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

Conductometric determination of naproxen in bulk and pharmaceutical dosage form

Effects of hydrogen bonding and homoconjugation on the titration curves of a synthetic polynuclear phenolic compound in non-aqueous solvents

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