ACIDIC CHARACTERIZATION

The American Society for Testing and Materials (ASTM) and the American Oil Chemists Society (AOCS) provide standard methods for determining properties that are important in characterization of dimer acids. Characterization of dimer acids for acid and saponification values, unsaponiftables, and specific gravity are done by AOCS standard methods ... 

Li, H., Lue, L., and Patrickios, C. S., Benzene oligocarboxylic acids characterization by isocratic, linear gradient, and frontal anion-exchange chromatography, /. Chromatogr. Sci., 37, 413, 1999. 

Essential fatty acid deficiency Deficiency of linoleic acid, linolenic acid, and/or arachidonic acid, characterized by hair loss, thinning of skin, and skin desquamation. Long-chain fatty acids include trienes (containing three double-bonds [e.g., 5,8,11-eicosatrienoic acid, or Mead acid trienoic acids) and tetraenes (containing four doublebonds [e.g., arachidonic acid]). Biochemical evidence of essential fatty acid deficiency includes a trieneitetraene ratio greater than 0.4 and low linoleic or arachidonic acid plasma concentrations. 

Table 6.5 contains a selection of Ka values. Acids characterized by large values of Ka are stronger than those with smaller values of Ka. Each Ka value in Table 6.5 was obtained at 298 K. Being an equilibrium constant, we anticipate temperature-dependent values of Ka, with Ka generally increasing slightly as T increases. 

Marchal-Roch, C. Bayer, R. Moisan, J.F. Teze, A. Herve, G. Oxidative dehydrogenation of isobu-tyric acid Characterization and modeling of vanadium containing polyoxometalate catalysts. Top. Catal. 1996, 5,407-419. 

Twenty Standard Amino Acids Characterized by Eight Binary Substructure... 

Characterization is an integral tool for the development of new zeolites and for the development and commercialization of zeolitic catalysts and adsorbents. Single techniques are not sufficient as they rarely provide full details of the system. A combination of selective characterization techniques is required. As suggested by Deka [1] even a single acidity characterization method may be insufficient to provide the necessary detailed information to understand the zeolite acid sites. Thus according to Deka the combination of different experimental techniques is required to shorten the time of development for a new catalyst. 

Auroux, A. (1997) Acidity characterization by microcalorimetry and relationship with reactivity. Top. Catal., 4,... 

The chinning response in tree shrews, Tupaia lelangeri, is triggered by several lipophilic fractions of male urine. The combined fractions are more active than single fractions. Pyrazine compounds and a high concentration of several volatile monocarboxylic acids characterize male urine. Some pyrazine compounds and some monocarboxylic acids release the chinning response (StralendorfF, 1987). 

Table IV. Acidity Characterization of Si02, 4% Mo03/Si02 and 5% V205/Si02 Catalysts...

Aldonic acids, characterization of, 373 —, 2-amino-2-deoxy-, deamination of, 191 —, 2,5-anhydro-, properties of, 220-229 Aldonolactones, 2-amino-2-deoxy-, deamination of, 189... 

Hydrogen fluoride in aqueous solution is a weak acid, characterized by its pKa value of 3.2. By comparison, the other hydrogen halides are extremely strong acids in aqueous solution all three are fully dissociated in dilute solution, and their pA", values may be estimated by thermochemical cycle calculations. The thermochemical cycle shown in Figure 3.1 represents the various processes as the aqueous hydrogen halide, HX, is converted to a solution containing hydrated protons and hydrated halide ions. The enthalpy of acid dissociation of the HX(aq) compound is given by ... 

For which of the following Bronsted bases is the reaction with acetic acid characterized by an equilibrium constant greater than 1 ... 

Figure 5.13 shows the structures of extrinsic fluors that have been of value in studying biochemical systems. ANS, dansyl chloride, and fluorescein are used for protein studies, whereas ethidium, proflavine, and various acridines are useful for nucleic acid characterization. Ethidium bromide has the unique characteristic of enhanced fluorescence when bound to double-stranded DNA but not to single-stranded DNA. Aminomethyl coumarin (AMC) is of value as a fluorogenic leaving group in measuring peptidase activity. 

The use of zeolites as selective catalysts in organic syntheses is a field of growing importance. Zeolites are salts of solid silicoaluminic acids characterized by a strictly regular structure of their crystalline lattice (ref. 1) and by their high acidity and shape selectivity (ref. 2). Attention to the broad potential of zeolites in organic reactions was first drawn in the sixties by Venuto (ref. 3) and various applications of their catalytic properties have been recently reviewed (ref. 4). 

Galacturonic acid, characterized, 739 Gas chromatography (GC) flame ionization detection (FID) characteristics of, 449 cholesterol, 461... 

Infrared (IR) has been used in two ways for structural characterization and for acidity characterization. The latter will be taken up in the next section. Vibrations between atoms produce characteristic frequencies in the IR region these are compared to known compounds to infer structural aspects of the catalyst. 

Derivatives of nonmetals and alcohols with very low acidity (pK=15-19). These are esters of inorganic acids, characterized by low melting and boiling points, solubility in alcohols and nonpolar solvents, and sensitivity even to the traces of water. They are usually monomeric or weakly aggregated. The representatives of this group areB(OR)3, P(OR)3 and Se(OR)4. 

The acidity strength of solid acids is still not well known and is difficult to measure. Claims of superacidity in solids are numerous and will be discussed later in Chapter 2. Among the reviews related to acidity characterization of solids, those of Corma, Farneth and Gorte, and Fripiat and Dumesic are quite significantly representative.30... 

Carboxylic acid An organic acid characterized by the presence of carboxyl, -C(0)0H. Acetic acid (CH3C(0)0H) is a carboxylic acid. 

Perfluoroalkyl acids (PFAs) are synthetic, perfluorinated, straight- or bran-ched-chain organic acids characterized by a carboxylate or sulfonate moiety [1]. PFAs are manufactured directly but can also be formed through transformation of many precursor molecules containing a perfluoroalkyl moiety [2], These include fluorotelomer alcohols (FTOHs) and perfluoroalkyl-sulfonamides (Table 1, Fig. 1), however, others likely exist. Collectively, this family of chemicals including PFAs and their polyfluorinated precursors will be referred to in this document as perfluoroalkyl substances (PFSs). 

Hundal, L. S., Carmo, A. M., Bleam, W. L., and Thompson, M. L. (2000). Sulfur in biosolids-derived fulvic acid Characterization by ZXANES spectroscopy and selective dissolution approaches. Environ. Sci. Technol 34, 5184-5188. 

Longaker, M.T. et al., Studies in fetal wound healing. V. A prolonged presence of hyaluronic acid characterizes fetal wound fluid, Ann. Surg., 213, 292, 1991. 

Balcao, V.M., Kemppinen, A., Malcata, F.X. and Kalo, P.J. 1998b. Lipase-catalyzed acidolysis of butterfat with oleic acid characterization of process and product. Enz. Microb. Technol. 23, 118-128. 

Shi et al. [98] introduced a pressurized capillary array system to simultaneously load 96 samples into 96 sample wells of a radial microchannel array electrophoresis microplate for high-throughput DNA sizing (Figure 13). As a result, 96 samples were analyzed in less than 90 s per microplate, demonstrating the power of microfabricated devices for large-scale and high-performance nucleic acid characterization. 

Table 9. Lewis acids characterized by ten property descriptors...

PTC in the production and testing of new drugs and biologies produced by recombinant DNA technology (4/85) Supplement on nucleic acid characterization and genetic stability (4/93)... 

---