Trichloroacetic acid indications

Fraction Fla was chosen for structural purposes due to its better solubility in water and the absence of Xyl. In order to remove noncovalently associated protein, fraction Flap was submitted to sequential shaking cycles with a mixture of chloroform-buthanol, as indicated by Sevag and described by Staub [17]. The fraction was also treated with trichloroacetic acid. In both procedures, coprecipitation of carbohydrate and protein was observed, suggesting strong linkages and a more complex structure. Fla as was submitted to mild acid hydrolysis yielding Flas and Flap (Table VI). 

Homopolymers of simple alkyl and aryl isocyanides (Mv.p.osm > 1000-4000) are insoluble in all common solvents. This statement, however, requires elaboration of the fact that trichloroacetic acid successfully disperses these polymers. Observations with poly(cr-toluyl isocyanide) are informative, since the polymer is canary yellow in color, and turns to dark brown in trichloroacetic acid—acting in the manner of an acid-base indicator dye. Dilution with water of the trichloroacetic acid solution of poly(aqueous alkali produces the original yellow color. It appears that the polyisocyanide is dispersed in trichloroacetic acid as a pro-tonated species. Conductimetric experiments on poly(a-phenylethyl isocyanide) in dichloroacetic acid confirm this view (25). 

Haiber G, Jacob G, Niedan V, Nkusi G, Scholer HF (1996) The Occurrence of Trichloroacetic Acid (TCAA) - Indications of a Natural Production Chemosphere 33 839... 

Hirvonen et al. (1995) evaluated the feasibility of the UV/H202 process for the removal of trichloroethylene (TCE) and erythromycin (perchloroethylene [PCE]) in contaminated groundwater. The formation of chloroacetic acids (CAs) was used as an indication of partial degradation. The dominant byproduct, dichloroacetic acid (DCA), accounted for the major part of the total yield of CAs. The observed concentrations of trichloroacetic acid (TCA) and DCA were relatively low compared with the total amount of TCE and PCE degraded. The effect of initial concentrations of the parent compounds, hydrogen peroxide, and bicarbonate on the yield of by-product was inves-... 

Molybdenum(VI)-catalysed perborate oxidation of sulfides is first order with respect to the sulfide and Mo(VI) but zero order in perborate. The uncatalysed reaction is first order in each the reductant and oxidant. Trichloroacetic acid enhances the oxidation rate. Oxidation of para-substituted. S -phenylmcrcaploacclic acids yielded a Hammett p of -0.54 at 293 K, indicating an electron-deficient sulfur atom in the transition state. 

Mono, di- and trichloroacetic acids have been also studied216,217. a-Iodoalkanoic acids CH3(CH2) CHICOOH (n = 9, 11, 13 and 15) have been studied under 24-eV and 70-eV El conditions218. An unusual iodine loss followed by consecutive eliminations of two molecules of water characterizes all the examined compounds, particularly at low El energy. According to the authors, the localization of the charge on the the a-carbon, determined by the I loss, initiates the fragmentation process as indicated in Scheme 30 (the value of x was not specified, probably x = 1,2). 

Alkaline hydrolysis of cockroach residues subsequent to extraction under nitrogen with 80% ethanol yielded methionine and methionine sulfoxide in a ratio of 10 to 1. Additional evidence for the presence of combined methionine sulfoxide was obtained by measuring the amount of methionine sulfoxide-S35 in acid and enzymatic hydrolyzates after assimilation of Na2S3504. The data are believed to be indicative of naturally occurring peptide- or polysaccharide -bound methionine sulfoxide. Other combined amino acids were determined by ion exchange chromatography of the 5% trichloroacetic acid-insoluble cockroach residues after hydrolysis with acid or alkali. /3-Alanine, normally present only in the soluble fraction of an organism, was found in the insoluble, proteinaceous residue. 

A trial was made to take a look at the valence of iron in adrenodoxin (29) using 3 moles of p-chloromercuribenzoate (PCMB) per gram atom of iron (less than saturated level of PCMB), all of the iron could be extracted by 5% trichloroacetic acid solution as ferric iron, which produces a ferrous-o-phenanthroline complex only by the addition of ascorbate as reductant. In the absence of the mercurial, some 50% or more of the iron atoms in the protein can be removed in the ferrous state. This result indicates that the acid extraction causes intramolecular reduction of the protein-bound iron. As shown in Fig. 10, 5.7 M urea as a protein denaturant can slowly bleach the visible absorption under aerobic conditions. About 10% of the residual absorption remains at 414 mp after the reaction is completed. In the presence of both urea and o-phenanthroline, all of the iron present in adrenodoxin reacts with o-phenanthroline to produce the ferrous complex under aerobic conditions. Similar experiments under anaerobic conditions reveal that the... 

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