Multicarboxylic acids

TABLE 5-VI Ionization Constants for Some Multicarboxylic Acids in Water at 25°C... 

Listed below are some acids and bases that are useful in preparing buffers for enzyme assays. The choice of a particular compound depends on many factors. For example, multicarboxylic acids would be poor choices for reactions involving metal ions as cofactors amino acids may be poor choices for reactions involving amino acids as substrates. The number of buffer components can be kept to a minimum by using an acid and a base to cover the desired region. For example, maleic acid and Tris can be mixed to produce Tris-maleate buffers of pH 5.7 to 8.6 (rather than using maleic acid-NaOH and Tris-HCl). 

A phyllosilicate-rich clay was studied by 29Si MAS-NMR spectroscopy.520 13C CP/MAS-NMR and 29Si MAS-NMR spectra were used to characterise silylated montmorillonites, and to estimate the extent of the silylation reaction.521 Ab initio calculations have been made of 29Si NMR chemical shifts for silicate complexes with carboxylates, amino acids and multicarboxylic acids.522 Structural changes on thermal treatment of kaolinite were followed using 29Si MAS-NMR spectra.523... 

While the majority of polynuclear lanthanide complexes and coordination polymers have been synthesized by the use of rigid ligands, such as multicarboxylic acids and carboxyphenyl porphyrin, relatively few studies involving more flexible ligands have been reported. However, the skeletal adapfabiUfy of flexible ligands enables them to form many different molecular systems and extended network... 

A particulate gel breaker for acid fracturing for gels crosslinked with titanium or zirconium compounds is composed of complexing materials such as fluoride, phosphate, sulfate anions, and multicarboxylated compounds. The particles are coated with a water-insoluble resin coating, which reduces the rate of release of the breaker materials of the particles so that the viscosity of the gel is reduced at a retarded rate [205]. 

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