Carboxylic acid systems

Litter, M.I. Baumgartner, E.C. Urmtia, G.A. Blesa, M.A. (1991) Photodissolution of iron oxides. 3. Interplay of photochemical and thermal processes in maghemite/carboxylic acid systems. Environ. Sci. Technol. 25 1907-1913... 

Wilson and Cannan (18) reported detailed observations on the equilibrium and velocity constants in the glutamic acid—pyrrolidone carboxylic acid system in dilute aqueous solution. They found that the conversion of glutamic acid to pyrrolidone carboxylic acid follows the equation for a reversible first-order reaction. The equilibrium constant and the rate at which the equilibrium is achieved depend on the pH of the solution and the temperature. In neutral solutions, the equilibrium favors almost complete conversion of glutamic acid to pyrrolidone carboxylic acid however, the rate of the reaction is very slow and thus only 1% conversion occurs after 2-3 hr at 100°. In weakly acid (pH 4) and alkaline (pH 10) solutions, the conversion of glutamic acid to pyrrolidone carboxylic acid is much faster and about 98% conversion occurs in less than 60 hr. In strong acid (2 N HC1) and base (0.5 N NaOH) the conversion of pyrrolidone carboxylic acid to glutamic acid proceeds rapidly and virtually to completion. Other studies have shown that the conversion of glutamic acid to pyrrolidone carboxylic acid can be carried out within 2 hr at 142° with little alteration of optical rotation (80). 

Polymerisations of tiiranes have been carried out in the presence of various catalysts containing multinuclear species, such as those formed in diethylzinc or dimethylcadmium-water, alcohol, diol, thiol or carboxylic acid systems, as well as catalysts containing mononuclear species, such as porphinatozinc thiolate (Tables 9.1 and 9.5). 

The Sodium Carboxylate/Carboxylic Acid System. This system has been investigated using IR and showing the extremely... 

The formation of transient organocopper compounds has been inferred in many decarboxylations of copper(I) carboxylates or copper-carboxylic acid systems 20, 33, 47, 56, 211, 213, 215, 279). Only one copper compound has been isolated, so far. Tbe decarboxylation of copper(I) pentafluorobenzoate in quinoline proceeds smoothly at 60°C to give a pentafluorophenylcopper-quinoline complex 33, cf. 254). 

Antibiotics PS-5 1 [1] and PS-6 2 [2], and other related structures such as thienamycin 3 [3] (Fig. 1), comprise an interesting family of streptomycete metabolites characterized by the presence of the 7-oxo-l-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid system 4 carrying an exocyclic aminoethyltio substituent at C3 of the pyrroline ring and alkyl side chains at the a-position adjacent to the P-lactam carbonyl. 

In a study of a poly(carboxylic acid) system based on poly(S-fllt-M), poly(styrene-fllt-maleic anhydride), several alky-lamide derivatives were prepared to investigate the influence of hydrophobidty on membrane activity and delivery ... 

Amphoterism phenomenon is the mechanism of acid-base interaction in systems formed by H-acids or two L-acids in binary systems. For example, in stannous tetrachloride-carboxylic acid system, acid-base interaction occurs with SnCl4 being an acid ... 

Clifford, S. L. Ramjugernath, D. Raal, J. D. Vapour-liquid equilibrium of carboxylic acid systems propionic acid -1- valeric acid and isobutyiic acid + valeric acid Fluid Phase Equilib. 2005,237, 89-99... 

CdSe/PMMA nanocomposites have also been used as chemical sensor for detection of aromatic hydrocarbons [196]. In that study, a series of surface-modified QDs, which utilized both TOPO and carboxylic acids attached to the surface of CdSe SC QDs, were developed. Unmodified QDs and surface-modified nanocrystals were incorporated into PMMA matrices, and the PL of nanocomposites was studied as a function of a series of exposures to toluene and xylene vapors ranging in concentration from ppm to percent levels. It was reported that reversible enhancement and quenching of the PL on film exposure to toluene and xylene vapors were both observed for the QDs modified by carboxylic acid systems. PL enhancement was observed at low target gas concentrations, with the onset of the quenching process for each of the films being dependent on the target gas type and its concentration [196]. 

For the addition of oxygen to a C=C double bond, reactive (electrophihc) oxygen has to be produced in situ by means of an activator from a stable oxygen donor. Activation of oxygen can be accomplished (1) by 0-0 bond transformation like in the classical percarboxylic acid - carboxylic acid system (see (a)) or (2) by interaction of O2, peroxides, or H2O2 with transition metals (see (b)/(c)) [16],... 

To provide sufficient rigidity to the core at least two ring systems are usually required. Rare exceptions are the 2,4-alkyldienoic carboxylic acids in which dimers are formed by hydrogen bonding of the carboxylic acid groups (which becomes a pseudo-ring system) indeed, most carboxylic acid systems behave in the same manner, e.g., 4-alkoxybenzoic acids (6). 

Finally, C—O single bond systems including ethers (III, B), esters (III, C), anhydrides (111, D), and peroxides (III, E) are examined toward the end of the chapter. Alcohol and carboxylic acid systems are considered in Chapter 6 where the focus is on the stretching vibrations. 

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