Carboxylic acid solubility

Figure 9 A synthetic mixture of water-soluble carboxylic acids separated by anion-exchange chromatography. Column 0.3 cm x 300 cm Diaoion CA 08, 16-20 p (Mitsubishi Kasei Kogyo). Eluant 200 mM HC1. Detection reaction with Fe3-benzohy-droxamic acid-dicyclohexy carbodiimide-hydroxylamine perchlorate-triethyl amine with absorbance at 536 nm. Analytes (1) aspartate, (2) gluconate, (3) glucuronate, (4) pyroglutamate, (5) lactate, (6) acetate, (7) tartrate, (8) malate, (9) citrate, (10) succinate, (11) isocitrate, (12) w-butyrate, (13) a-ketoglutarate. (Reprinted with permission from Kasai, Y., Tanimura, T., and Tamura, Z., Anal. Chem., 49, 655, 1977. 1977 Analytical Chemistry).

Powdered KMn04 (1.2 mol) is added portionwise at <30°C over 2 h to the alkene (0.03 mol) and Aliquat (0.2 g, 0.5 mmol) in CH2C12 (n-C5H 2 or PhH) (100 ml) and AcOH (30 ml). The mixture is stirred at room temperature for 12 h and aqueous NaHSO, (5%, 100 ml) is then added. The aqueous phase is separated, acidified with concentrated HC1, and the carboxylic acid is collected (if it has precipitated), or the acidic solution is saturated with NaCI and extracted with Et20 (2x10 ml). Evaporation of the ethereal extracts yields the water-soluble carboxylic acid. 

Ketopregnan-21-oic Acids, the 17 3-Carboxy Androstanes, and the D-Homocorticoids. In the course of studies on the metabolism of fluocortolone (103) the formation of the water-soluble carboxylic acid (105, R = H) was reported. As a free 21-hydroxyl is not necessary for antiinflammatory activity, it was concluded that the esters (105, R = alkyl) of the preceding metabolite would possess antiinflammatory activity on topical administration but would be devoid of systemic activity when hydrolysis to the free acid occurs followed by... 

Positive-Tone Photoresists based on Dissolution Inhibition by Diazonaphthoquinones. The intrinsic limitations of bis-azide—cyclized rubber resist systems led the semiconductor industry to shift to a class of imaging materials based on diazonaphthoquinone (DNQ) photosensitizers. Both the chemistry and the imaging mechanism of these resists (Fig. 10) differ in fundamental ways from those described thus far (23). The DNQ acts as a dissolution inhibitor for the matrix resin, a low molecular weight condensation product of formaldehyde and cresol isomers known as novolac (24). The phenolic structure renders the novolac polymer weakly acidic, and readily soluble in aqueous alkaline solutions. In admixture with an appropriate DNQ the polymer s dissolution rate is sharply decreased. Photolysis causes the DNQ to undergo a multistep reaction sequence, ultimately forming a base-soluble carboxylic acid which does not inhibit film dissolution. Immersion of a pattemwise-exposed film of the resist in an aqueous solution of hydroxide ion leads to rapid dissolution of the exposed areas and only very slow dissolution of unexposed regions. In contrast with crosslinking resists, the film solubility is controlled by chemical and polarity differences rather than molecular size. 

Solubilities Carboxylic acids form hydrogen bonds with water, and the lower-molecular-weight acids (up through four carbon atoms) are miscible with water. As the length of the hydrocarbon chain increases, water solubility decreases until acids with more than 10 carbon atoms are nearly insoluble in water. The water solubilities of some simple carboxylic acids and diacids are given in Tables 20-1 and 20-2. 

Fullerenes Very tiny balls consisting of 60 carbon atoms with diameter of 0.7 nm Water-soluble carboxylic acid Cm derivatives acting as antimicrobials, being linked to a variety of active molecules 25, 38, 39... 

Positive Photoresists. Positive resists are entirely different from negative resists. For the purposes of this discussion we restrict ourselves to visible-light-sensitive materials. Typically, these materials are mixtures of low-molecular-weight phenol-formaldehyde polymers and derivatives of naphtho-1,2-quinone diazide, the photosensitive component. The former is soluble in aqueous alkali, but the presence of the latter, a hydrophobic species, inhibits attack of this developer on the film. On irradiation the "sensitizer" is converted to a ketene, which, after reaction with water, forms a base-soluble carboxylic acid. Thus the irradiated part of the film is rendered soluble in the developer and it can be removed selectively. The important feature of this system is that the unirradiated areas are not swollen by the developer and the resolution of this material is quite high. It is possible to prepare gratings having several... 

A is the surface area, and t is time. A sigmoidal curve, reminiscent of a titration curve, was obtained when the initial rate of monolayer contraction, Rif was plotted as a function of pH (23). The apparent pKa, estimated from the midpoint of the sigmoidal curve, depended on the chain length and the degree of unsaturation of the fatty acid. The apparent pKa always exceeded the pKa for soluble carboxylic acids. 

Anilide formation of highly water-soluble carboxylic acids including fluoroacetate, mono-, di-, and trichloroacetate has been carried out using dicyclohexylcarbodiimide (Ozawa and Tsukioka 1990). 

Flotation depressants It was indicated earlier that the release of oil soluble carboxylic acids may be responsible for the retention of Ca/Ca-Mg carbonates by the kerogen-organic binder pellets. Chemical flotation depressants are sometimes applied to overcome the collecting tendency of fatty acids and thus to increase the water wettability of the carbonate particles in the presence of carboxylin acids.( ) The introduction of such flotation depressants, including sodium oxalate, chromium nitrate, copper nitrate, ferric sulfate and aluminum nitrate failed to improve the beneficiation process described here. 

Soluble carboxylic acids behave as weak acids they dissociate only slightly in water to form an equilibrium mixture with the carboxylate ion. The equilibrium concentrations of the carboxylic acid and the carboxylate ion depend on pH. At low pH, the acid form predominates, and at pH 7.4 (the pH of cellular fluids) and above, the carboxylate ion predominates. Carboxylic acids react with bases to produce carboxylate salts and water. Objective 3 (Section 5.3), Exercise 5.26... 

Aqueous solutions of water-soluble carboxylic acids give an acid test with blue litmus paper. 

There are other published resolutions of 4-hydroxyphenylglycine, one of which involves the enzyme-catalysed hydrolysis of the ethyl ester (Scheme 6.9). Since the substrate is fully blocked at the amino and the carboxylate functions, it is scarcely soluble in water and must be dissolved in an organic solvent. The specific hydrolysis of the ester catalysed by an enzyme in an aqueous phase in contact with the organic solvent will yield a water-soluble carboxylic acid which transfers to the aqueous phase containing the enzyme. The conditions of the reaction therefore effect both hydrolysis of the ester and facile separation of the product. In fact, the enzyme is immobilized on a hydrophilic membrane at the interface between the two immiscible phases. The membrane reactor (Figure 6.2) comprises a large bundle of hollow fibres, each having an external diameter of about... 

A water-soluble phenol is also acidic toward litmus paper as is a water-soluble carboxylic acid. How would you distinguish the difference between an aromatic acid and a phenol using a chemical test ... 

Even higher Xe-binding constants from aqueous solutions have been reported for the water-soluble, carboxylic acid-derived 23 and 24. ... 

When neutral solutions of uranyl-, ferric-, or bismuth nitrate (chloride) are shaken with a benzene solution of Rhodamine B, the benzene layer turns red and exhibits an intense orange fluorescence in ultraviolet light. This effect is surprisingly heightened if a little benzoic acid or some other benzene-soluble carboxylic acid is added to the benzene solution. In the case of uranyl salts, the color (fluorescence) reaction is so marked that a sensitive... 

The sparingly water-soluble carboxylic acid cryptophane 8 was prepared from cryptophanol-A 2. Although its solubility is very limited in water, the Xe 8 complex can be easily detected in water thanks to high sensitivity laser-polarized... 

Other mixtures of water and organic solvents have also been proposed to titrate some other poorly soluble carboxylic acids. Examples are water/DMF and water/acetone. The indicators used are bromothymol blue and phenolphthalein. 

Water-soluble carboxylic acids have been found in oil-field formation waters from around the world (Carothers and Kharaka 1978 Surdam et al. 1984 Hanor and Workman 1986 Fisher 1987 Means and Hubbard 1987 MacGowan and Surdam 1988, 1990 Barth et al. 1990 Fisher and Boles 1990 Lundegard and Kharaka, Chap. 3, this Vol.) with total concentrations reaching up to 10000 ppm (Surdam et al. 1984). Total concentrations and abundances of individual species vary widely and only a few of the simple monofunctional and difunctional groups have been identified in each study. Typically, monofunctional carboxylic acids (formic, acetic, propionic. 

The role played by short-chain, mono- and dicarboxylic acids in the evolving chemistry of sedimentary basins - processes such as the mass transport of metals, the dissolution/precipitation of carbonates and aluminosilicates, and the migration of methane - can only be assessed given knowledge of their stability under prevailing hydrothermal conditions, specifically temperatures up to 200 °C. Substantial concentrations of water-soluble carboxylic acids are... 

In this chapter, the water-soluble carboxylic acids are divided into two homologous series, because aliphatic mono- and dicarboxylic acids behave quite differently with respect to thermal decomposition. Specifically, dicarboxylic acids readily undergo thermally induced homogeneous decarboxylation whereas, in all experiments conducted to date, unimolecular decarboxylation of monocarboxylic acids effectively would not occur under relevant hydrothermal conditions in the absence of a heterogeneous catalyst. Evidence for this duality of mechanism will be presented in the forthcoming discussion, but will be restricted primarily to acetic, oxalic, and malonic acids for which extensive experimental information is available. Moreover, a critical discussion will be presented of the current state of experimental... 

For source-reservoir rock systems in the 80 to 130 °C temperature interval, four important and overlapping sources of carboxylic acids/acid anions in the fluid phase have been identified. All four processes are capable of generating significant quantities of water-soluble carboxylic acids/acid anions. Thus, it is not surprising that the alkalinity of the fluid phase in source/ reservoir rock systems in the 80 to 110°C ( 10°C) temperature interval typically is dominated by OAA. 

Organic aqueous two-phase solvent systems are also widely applied for other biotransformations, for example, in hydrolase-catalyzed processes [37,49]. A typical example is the enantioselective hydrolysis of a racemic, water-immisdble ester as a substrate. The reaction yields a water-soluble carboxylic acid (in depro-tonated form as a salt). Ionic liquids have also been used in biphasic systems, a topic that is discussed in detail in Chapter 3 in this book [50]. 

As discussed in Chapter 16, soluble carboxylic acids behave as weak acids when they dissolve in water. A simple way to test whether a compound is a carboxylic acid is to add it to an aqueous solution of sodium hydrogen carbonate, NaHC03(aq), or sodium carbonate, Na2C03(aq). If the compound is an acid, bubbles of C02(g) will be visible because of the following reaction. 

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