Carboxylic acid short-chain

The idea that inulin-type fructans are fermented by bacteria colonising the large bowel is supported by many in vitro (both analytic and microbiological) and in vivo studies, which, in addition, confirm the production of lactic and short-chain carboxylic acids as end products of the fermentation (Tanner, 2005). Furthermore, it was shown inhuman in vivo studies that this fermentation leads to the selective stimulation of growth of the bifidobacteria population, making inulin-type fructans the prototypes of prebiotics (Roberfroid, 1997 Roberfroid, 2001). 

Unwanted oxygenates were removed from the organic product and specifically the short-chain carboxylic acids that were known to cause problems.24... 

Short-chain carboxylic acids, e.g. 2-, and 3-methylbutyrate Fusel alcohols Gluconobacter, Acetobacter Up to 95 g L, 72 h Two-step cultivation biomass + bioconversion period used as flavour acids but also for ester syntheses [39]... 

Studies on reaction mechanisms and by-product analysis have indicated that short-chain carboxylic acids, ketones, aldehydes, and alcohols are the major oxidation intermediates under near-critical conditions, but at supercritical conditions, with T above 650 °C, no intermediate compounds have been found [7]. 

Short-chain carboxylic acids are quite soluble in water and tend to ionize slightly (typically, a few percent depending on concentration). These acids undergo the typical acid-base reactions. Besides the condensation reaction with alcohols, acids condense with ammonia or amines to form amides. 

When fats or oils are exposed to air, they react with the oxygen or water vapor to form short-chain carboxylic acids. The short-chain acids are volatile and have unpleasant smells and tastes. For example, the strong smell and sour taste of vinegar are due to acetic acid, a two-carbon carboxylic acid. The oxidation process is called rancidification and can make foods unpalatable. The characteristic smell of rancid butter is due to the presence of butyric acid (a four-carbon acid). (Rancidity can also be the result of the hydrolysis of fats or oils.)... 

The use of a classical anode such as Pt in anodic oxidation usually leads to a partial mineralization of wastewaters containing aromatics due to the formation of final short-chain carboxylic acids, as oxalic acid, that hardly react with OH. Overall mineralization is feasible with a boron-doped diamond (BDD) anode that possesses a much greater 02 overpotential compared to Pt, thus producing a higher amount of... 

Fe, on the other hand, has been used directly in PC processes as a dopant in semiconductors, in particular for Ti02. The results seem to be somewhat contradictory nonetheless. These doped catalysts have been tested in the PC reactions of short-chain carboxylic acids such as maleic, formic, and oxalic acids, among others. 

Cesium salts of iV-protected amino acids were introduced by Gisin [15] for the synthesis of ester bonds under mild reaction conditions in the solid phase synthesis according to Merrifield [48]. Cesium salts of short chained carboxylic acids like cesium propionate found broad application for the selective inversion of the stereochemistry of secondary alcohols which could be performed with cesium salts under careful reaction conditions [49, 50]. 

Polyketide and fatty acid biosyntheses begin with condensation of the coenzyme A thioester of a short-chain carboxylic acid starter unit such as acetate or propionate with the coenzyme A thioester of a dicarboxylic acid extender unit such as malonate or methyl malonate. The driving force for the condensation is provided by the decarboxylation of the extender unit. In the case of fetty acid synthesis, the resulting -carbonyl is completely reduced to a methylene however, during the synthesis of complex poly-ketides, the -carbonyl may be left untouched or variably reduced to alcohol, olefinic, or methylene functionalities depending on the position that the extender unit will occupy in the final product. This cycle is repeated, and the number of elongation cycles is a characteristic of the enzyme catalyst. In polyketide biosynthesis, the full-length polyketide chain cyclizes in a specific manner, and is tailored by the action of additional enzymes in the pathway. 

Mixed Carboxylate-Sulfonate Systems. Decanolc and octanoic acids were selected as carboxylic acids in view of their intermediate chain lengths. Some initial experiments using a short-chain carboxylic acid (isobutyric acid) were not very promising, apparently because only a fraction of the acid would partition to the drop surface. 

Fig. 15.11 Factors affecting pH after a 10% glucose or sucrose mouth rinse. Dashed line indicates pH 7. Vectors 1 and 4 increase the pH vectors 2 and 3 decrease the pH. The short-chain carboxylic acids (SCCA) may be produced from amino acids along with ammonia, or from the catabolism of lactic acid (see text and also Fig. 1.8). (From Fig. 9 in Kleinberg I, 2002. A mixed-bacterial ecological approach to understanding the role of the oral bacteria in dental caries causation an alternative to Streptococcus mutans and the specific-plaque hypothesis. Crit Rev Oral Biol Med 13 108-125)...

Numerous electrokinetic studies (see, e.g., [47]) have been carried out in the presence of pH buffers. These results are not used in the present compilation, because the components of pH buffers usually show specihc adsorption. Mixed evidence is found in the literature regarding specihc/nonspecihc character of adsorption of short-chain carboxylic acids. Reference [48] suggests an absence of a shift in the lEP of alumina (0.5 g/L) in the presence of >0.001 M organic acids. The effect of specihc adsorption on the electrokinetic curves became visible at pH < lEP. No shift in the lEP of titania in the presence of CHjCOONa or C2H5COONa was observed [49], but sodium salts of higher carboxylic acids induced a shift in the lEP to low pH. 

Fig. 2 GC-MS chromatograms showing the products extracted from photo-oxidized polyethylene by traditional HS extraction (above) and by HS-SPME with polar car-bowax/divinylbenzene fiber (below). A few short-chain carboxylic acids were detected in the chromatogram after HS extraction, while carboxylic acids, ketones and furanones were detected after HS-SPME...

Fatty acids have several important chemical properties. The reactions that they undergo are typical of short-chain carboxylic acids. For example, fatty acids react with alcohols to form esters ... 

A number of protic acids have been used to catalyze acylation reactions. It is assumed that the reactions involve the generation of acylium ions. Polymeric reagents such as Nafion-H have been used for example 2-fluorobenzoyl chloride and toluene give the benzophenone derivatives with an ortho.para ratio of 4 81. ° A zeolite-catalyzed acylation (equation 6) has been reported to afford 4-dodecenoyltol-uene in 96% yield but the yields are low with short chain carboxylic acids. Early examples of the use of trifluoroacetic and perchloric acids reported good yields of products. Some more recent examples are shown in equations (7) to (9). Phosphoric and polyphosphoric acids have been used together with carboxylic acids (equation 10),anhydrides and acylureas (equation 11). °... 

The reactions of fatty acids are identical to those of short-chain carboxylic acids. The major reactions that they undergo include esterification, acid hydrolysis of esters, saponification, and addition at the double bond. 

The simplest HDAC inhibitors are short chain carboxylic acids such as butyric acid, where presumably the acid is the zinc-binding group. These are relatively low in potency (micromolar IC50). Valproic acid, an old drug used as an anticonvulsant, is similarly a modest H DAC inhibitor and has now advanced to clinical trials as an anticancer agent (Fig. 12-5). The low potency, combined with short half-life and metabolic instability are the liabilities associated with this class of HDAC inhibitors. 

In the subterranean parts of V. officinalis, a number of alkaloids (0.05-0.1%) occur actinidine, 8-methoxyactinidine (valerianine) and naphthyridylmethylketone have been found as well as several other, yet unidentified alkaloids. Furthermore, isoferulic acid, y- aminobutyric acid, free fatty acids and short-chain carboxylic acids have been isolated. In the leaves of V officinalis, the presence of four flavonoids has also been demonstrated. From the subterranean parts of V. jatamansi, isomers of lanarin isovalerate and 4-methoxy-8-pentyl-l- naphtholic acid were isolated and characterized [50, 51]. 

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