Carboxylates acid-base titration

Because synthetic products are isolated as the barium or, more frequently, the calcium salt of leucovorin, common acid-base titrations are not reported. If this type of titration or one in which the cation is exchanged were feasible, the results would require careful interpretation because impurities containing the glutamic acid moiety would respond similarly to leucovorin when the carboxyl groups are being analyzed. 

HPMA [36] and a vinyl metal-chelating monomer A-(A/, A/ -dicarboxy-methylaminopropyl)methacrylamide synthesized [35]. Chemical structures of HPMA and DAMA are given in Figure 4. Poly(HPMA-co-DAMA) was prepared by free radical copolymerization in methanol with AIBN as initiator. Molecular weight distribution was determined by size exclusion chromatography and content of side-chain carboxylic group by acid-base titration. 

The authors determined the amounts of carboxylate anion and carboxylic acid in the polymer by acid-base titration. By assuming the polymer contains an equal number of moles of ammonium cation and carboxylate anion an additional estimate of the number of monomeric units per ammonium ion was obtained. It, twelve, falls between the other two. 

Acid-base titrations of humic substances reflect the nature of the different p/Tfl values, hence the smeared out appearance of these titration curves. While no unique equivalence points are observed, different p regions of carboxylic and phenolic groups can be discerned. Similarly, in metal titrations, metal ions are bound differently by the different ligand groups. The extent of metal-ion binding depends on the ratio of metal ions to humic substances, [M7]/ [L7-]. In titrating humic or fiilvic acids with metal ions (at fixed pH), the metal is bound first to the highest affinity sites. 

Carboxylic Acid Capacity. Alginic acid carboxylic acid capacity was determined in triplicate by acid-base titration. A known excess of 0.050 M NaOH was... 

Complexing betaines 39 and 40 with strong polyanions such as polystyre-nesulfonate sodium salt reduces intramolecular interaction and acid-base titration becomes possible [85]. In pure poly(4-VP) based polycarbobetaines only 10-15% of the carboxylic groups are titratable [64]. 

The stoichiometry of the proton in Eqs. (10.7) and (10.8) (denoted by j) is a collective term that represents three possible configurations for the M Hy cit +- - (6Z ) complex. The value of j is 1 when Hc iP occurs in the complex, as in MHcif (6Z ). In this instance, a single carboxyl and the hydroxyl are protonated on the citrate molecule. Such complexes are significant only when solution pH values are less than 4. More commonly, j is zero or negative, the latter representing either the occurrence of H iciP in the complex (all citrate moieties ionized) [as in MH icit (ag)], or the occurrence of H ciP and a metal hydrolysis product in the complex [as in MOH(H icit)2 (ag)]. Chemical models derived from potentiometric acid-base titration studies cannot distinguish between the two potential proton sources (citrate hydroxyl or metal-bound water), as titrations... 

These reactions were studied in terms of steric effect, acidity and basicity of carboxylic acids, amines, and tertiary amines (e.g. pyridine) by using phosphorous acid and its mono-, di-, and tri-esters, as proposed in Scheme 1 for the case of the reaction with diesters. These N-phosphonium salts (i-4) were separated and characterized on the bases of the IR spectra, acid-base titration, and their reactions. 

The determination of the carboxyl content in the CTPnBA. The method is based on a potentlometrlc acid-base titration technique in organic solution. 

Functionality. The number of carboxyl equivalents was determined from the potentlometrlc acid-base titration. The number molecular weight iii of the CTPnBA was determined by the Vapor Pressure Osmometer measurement. The product of the number of acid equivalents by the molecular weight divided by the weight of the titrated PnBA sample is the calculated average number of carboxyl groups per chain of the poly n-butyl acrylate. 

The combined sulphonated carboxylic acid and fatty acid or their salts are determined by potentiometric acid-base titration, after oxidation of sulphite/sulphur dioxide. 

The carboxylate group of monoalkylsulphosuccinates is determined by acid-base titration. Both mono- and dialkyl sulphosuccinates are readily hydrolysed by alkalis, and the hydrolysis and subsequent extraction of... 

All may be determined by two-phase or potentiometric titration with benzethonium chloride. Titration of sulphosuccinamates in acid solution measures the sulphonate group alone (but see section 5.13.3), and titration in alkaline medium measures the carboxylate group as well (cf. section 5.11.3). Sulphosuccinamates, possessing a carboxylate group, can also be determined by potentiometric acid-base titration. 

Fatty acids and acyl sarcosines may be extracted with petroleum or diethyl ether from an acidified aqueous solution if no other surfactants are present, or with petroleum ether from acidified 50% ethanol if they are. The extract is evaporated and the residue weighed. Alkylether carboxylic acids cannot be quantitatively extracted with petroleum ether. They can be extracted from aqueous solution with chloroform, but they are best determined by two-phase titration with benzethonium chloride in akaline solution (bromophenol blue method) or direct potentiometric acid-base titration. 

EEC titration in alkaline solution measures both species. EEC titration in acid solution measures only the sulphate or sulphonate. Potentiometric acid-base titration in alcoholic solution measures only the carboxylate. 

Carboxylates with quats. SDS titration in acid solution BEC titration in alkaline solution potentiometric acid-base titration in ethanol or propan-2-ol. 

Carboxylates with weakly basic cationics. As for quats. Results of acid-base titration must be interpreted bearing in mind the degree of protonation or deprotonation in the product acid titration measures free bases plus carboxylate anions, titration with alkali measures free acids plus protonated amine cations. If only weak acids and bases are present, acid titration measures the bases and alkali titration the acids. 

That approach is useless for SW amphoterics BEC titration measures the total active and SDS titration in acid solution measures nothing. Acid-base titration measures both the acid group of the carboxylate and the basic group of the amphoteric. If the sample is dried and dissolved in glacial acetic acid, the amine function of the SW amphoteric can be titrated with perchloric acid in glacial acetic acid, but it is likely that other weak bases will be present. Extraction of the carboxylic acid is the simplest way. 

There are two major areas of use for nonaqueous acid-base titrations. The first is the direct determination of compounds that have definite acidic or basic properties. This includes many thousands of organic compounds. For example, many amines are basic and can be titrated. There are also numerous acidic compounds, such as sulfonic acids, phosphonic acids, carboxylic acids, enols, imides, phenols, sulfur compounds, and others which can be titrated. The second largest and most important use of nonaqueous acid-base titrations is the indirect deter-... 

Figure 4 shows a simulated acid-base titration curve for two natural PE chitosan and alginate. It can be seen that in the case of alginate (an acid PE), turbidity starts to increase at pH below 4.0 [23]. In this area of acidic pH, the carboxylic groups of the PE molecule are protonated, which decreases PE... 

Acid-base titrations showed that during the calcination and reduction processes many basic sites were lost, thus leading to lower catalyst pH values for the catalysts than for the starting N-CNT supports (Table 1). This might be due to the loss of carboxylic acid groups during the catalyst preparation. The low specific area of Pd/N-CNT is due to the wall thickness of the CNTs [15]. Pd/AC exhibited the lowest pH. 

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