Organic acid origin

Lundegard P. D. (1985) Carbon dioxide and organic acids origins and role in burial diagenesis (Texas Guff Coast Tertiary). Ph.D. thesis. University of Texas at Austin, Austin, Texas, 145pp. 

TABLE 4.6 Organic acids origin and microorganism involved in their formation... 

Various biologieal faetors affeet eorrosion in soils. Organic acids originating from humus are relatively eorrosive versus steel, zinc, lead and copper. In certain soil types, particularly acidic clay, very high corrosion rates have been experieneed under anaerobie eonditions. This is commonly caused by sulphate-reducing bacteria, which is indicated by ferrous sulphide found as part of the corrosion products. The mechanism of this type of eorrosion has been dealt with in Section 6.4. 

In the separations (2) and (3) above, it is often advisable to dissolve the original mixture in a water-insoluble solvent. Select a solvent which will dissolve the entire mixture, and then shake the solution with either (i) dil. NaOH or (ii) dil. HCl. Separate the aqueous layer, and to it add either (i) dil. HCl or (ii) dil. NaOH to liberate the organic acid or the organic base, as the case may be. The non-aqueous layer now contains the neutral component. Reextract this layer with either (i) dil. NaOH or (ii) dil. HCl to ensure removal of traces of the non-neutral component. 

Numerous organic acids iu coffee iuclude acids of metaboHc origin, eg, acetic lactic, citric, malic, and oxaUc free quiuic acid [77-95-2], and various chlorogenic acid (CGA) isomers that appear to be species specific. 

The main constituent of all fibers of vegetable origin (see Table 88) is, almost exclusively, cellulose, a polymeric carbohydrate (see Textbox 53). Vegetable fibers are resistant to alkalies and to most organic acids but are destroyed by strong mineral acids. 

Many organic acidurias originate in the breakdown of the three branched-chain amino acids, leucine, isoleucine and valine (Fig. 40-1). Metabolism of the organic acids requires the presence of specific enzymes, congenital... 

Lowry praised the 1916 memoir of the American chemist Lewis as a "turning point in the history of chemistry" with its "plausible theory" of the electronic origin of the different types of chemical affinity and a clear differentiation between two kinds of valence, ionic and covalent. It is customary in mineral chemistry, he said, to consider reactions that occur between ions to be instantaneous, without attaching any importance to ionization in organic chemistry, except for the formation of salts from organic acids. 

One example is the separation of tricarboxylic acid cycle organic acids. These organic acids were originally separated on sulfonic acid-treated silica gel as the stationary phase material, and a chloroform and isopentyl alcohol mixture was used as the eluent. However, this eluent is not suitable for UV detection. A mixture of -hexane, THF, and ter/-butanol was therefore selected for the same separation.74... 

Although sulfur vulcanization has been studied since its discovery in 1839 by Goodyear, its mechanism is not well understood. Free-radical mechanisms were originally assumed but most evidence points to an ionic reaction [Bateman, 1963]. Neither radical initiators nor inhibitors affect sulfur vulcanization and radicals have not been detected by ESR spectroscopy. On the other hand, sulfur vulcanization is accelerated by organic acids and bases as well as by solvents of high dielectric constant. The ionic process can be depicted as a chain reaction involving the initial formation of a sulfonium ion (XI) by reaction of the polymer with polarized sulfur or a sulfur ion pair. The sulfonium ion reacts with a polymer molecule by hydride... 

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