Amino Acids and Anilines

Edentate and other anilines can be used to adjust the ionic composition of ore pulp. Therefore, they can be used as depressant to improve the selectivity of mineral in flotation process. The depressant CYQUEST comprises amino acids and anilines. The flotation results of mineral using CYQUEST are listed in Table 4.3. 

Amino acid depressants are usually the crude products which are prepared from protein-containing industrial wastes via hydrolysis reaction. Aniline depressants are usually the semifinished products or by-products of dyestuff industry. The foreign depressant Nigrosine is comprised of nitrobenzene, aniline, and aniline hydrochloride. This reagent can be used as the depressant of gangue, slurry, and carbonate minerals. 

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Specific reagents react with a particular class of compound, For example, rhodamine B is often used for visualization of lipids, ninhydrin for amino acids, and aniline phthalate for carbohydrates. 

Nonelectroactive benzene or toluene can be quantitatively converted to electroactive nitroderivatives. The method can be extended to any polarographic-ally inactive but easily nitrated aromatic compounds such as phenols, phenyl-bearing amino acids, and aniline derivatives. Interesting discriminations between similar compounds based on their ability to be nitrated or not can be achieved. Thus, the readily nitrated phenylbarbituric acid (phenobarbital) can be polarographically determined in the presence of a 100-fold excess of diethylbarbituric acid (barbital). The nitration of morphine also provides an excellent route for the polarographic determination of this otherwise practically nonelectroactive alkaloid. 

Acid Orange 7 Sludge originally collected from a pulp and paper wastewater treatment plants Color removal of 96% was achieved in the presence of liposomes that facilitated uptake of dyes by anaerobic biomass, leading to a fast decolorization. Amines such as sulfanilic acid and aniline were mineralized by inocula with high microbiological diversity, even with domestic effluent. Orthanilic and metanilic acids and 1-amino-2-naphtol were persistent under tested conditions [176]... 

Polymers and resins Water purification, including removal of phenol, chlorophenols, ketones, alcohols, aromatics, aniline, indene, polynuclear aromatics, nitro- and chlor-aromatics, PCB, pesticides, antibiotics, detergents, emulsifiers, wetting agents, kraftmill effluents, dyestuffs recovery and purification of steroids, amino acids and polypeptides separation of fatty adds from water and toluene separation of aromatics from ahphatics separation of hydroquinone from monomers recovery of proteins and enzymes removal of colours from symps ... 

Photolytic. Napropamide decomposes under UV light. Under laboratory conditions, irradiation of an aerated aqueous solution with UV light yielded 2-hydroxypropananilide, 2-propenanilide, and pyruvinanilide as the major products. Minor photoproducts include 2-(2-naphthoxy)propanoic acid and aniline (Tsao and Eto, 1990). In a deaerated aqueous solution, the photoproducts identified were 2-hydroxypropananilide, 2 -amino-2-hydroxypropiophenone, 2 -amino-2-naphth-oxypropiophenone, and 4-amino-2-naphthoxypropiophenone. 

Solvent systems used for thin layer chromatography were 1) n-butanol acetic acidiwater (4 1 5 upper phase), 2) acetic acid water (15 85), 3) ethyl acetate pyridine water (12 5 4), and 4) chloroform acetic acid water (50 45 5). Silica gel plates were used for chromatography of flavonoid aglycones and cellulose plates for all other components. Aluminum chloride was used for detection (under long UV light) of flavonoids, aniline phthalate for sugars, ninhydrin for amino acids and iodine for other components. Cellulose thick layer plates were developed with solvents 1 or 2. 

It is not possible to prepare biaryls containing a free carboxyl group directly by the diazo reaction. No biaryl is formed when (a) diazotized aniline and sodium benzoate, (b) diazotized anthranilic acid and aqueous sodium benzoate, or (c) diazotized anthranilic acid and benzene are used as components in the reaction.13 On the other hand, the reaction proceeds normally if methyl benzoate is used in reaction (a) or when methyl anthranilate replaces the anthranilic acid in (b) and in (c). The success of the diazohydroxide reaction appears to lie in the ability of the non-aqueous liquid to extract the reactive diazo compound from the aqueous layer.4 However, esters and nitriles can be prepared from esters of aromatic amino acids and cyanoanilines and also by coupling with esters of aromatic acids, and from the products the acids can be obtained by hydrolysis. By coupling N-nitrosoacetanilide with ethyl phthalate, ethyl 4-phenylphthalate (VIII) is formed in 37% yield. 

On treatment of 3 with semicarbazide a crystalline semicarbazone is formed (55), and the reaction with aniline yields a salmon-pink Schiflf base 06 nm) (81). The formation of betalains by reaction of 3 with amino acids and amines is discussed in Section VIII,C. 

The protein polysaccharide is hydrolyzed at 100-110° for 3 hours with N sulfuric acid, neutralized with baryta solution, filtered, and the filtrate concentrated to small volume. Zone electrophoresis in borate buffer (pH 8.6) is then carried out for a suitable time, and the paper strip is dried and sprayed with ninhydrin (to locate the amino acids) and with aniline hydrogen phthalate (to detect the reducing sugars). 

The relative positions of the amino acids and sugars may give useful information. Alternatively, the paper may be subjected to chromatography in a direction at right angles to that of the zone electrophoretic separation in which case, the paper should finally be sprayed rs< with aniline hydrogen phthalate and then with ninhydrin. 

The situation is not so clear cut with the aromatic amino acids, and it becomes more difficult to assign Ki and K2- This is because benzoic acid and aniline have very similar p TaS, and, on the basis of magnitude alone, p 2 could be assigned to the acid-base behaviour of either the amino or the carboxyl group. The pATj values for the aminobenzoic acids are significantly lower than the p TaS for aniline and substituted anihnes and for benzoic acid and substituted benzoic acids. However, the p Ta values for the methyl amino benzoates do give a clue. In these... 

Compounds of structure 10 react readily with nucleophiles. Thus moisture causes rapid hydrolysis to the pyrazine amino acid, and aliphatic amines give the amides (11), which may be cyclized to pteridinones (12) by dissolving in phosphoryl chloride. Ammonia, hydroxylamine, and aniline give the pteridinones (13) directly. ... 

Aniline also cannot be nitrated because nitric acid is an oxidizing agent and primary amines are easily oxidized. (Nitric acid and aniline can be an explosive combination.) Tertiary aromatic amines, however, can be nitrated. Because the tertiary amino group is a strong activator, nitration is carried out with nitric acid in acetic acid, a milder combination than nitric acid in sulfuric acid. About twice as much para isomer is formed as ortho isomer. 

Further hydrolysis would yield an a-amino carboxylic acid and aniline. 

A simple case of the general transpeptidation reaction was the trans-amidation resulting in the formation of hippuric anilide from aniline and hippuric amide in the presence of papain. Since this reaction proceeded much faster than the enzymatic synthesis of hippuric anilide from hippuric acid and aniline, it seems reasonable to infer that exchange, in the former reaction, took place between the aniline and ammonia. Waley and Watson subjected L-lysyl-L-tyrosyl-L-lysine and L-lysyl-L-tyrosyl-L-leucine to treatment with chymotrypsin and trypsin at pH 7.8. In the hydrolysis mixture of either of these substrates they were able to identify lysyllysine which could have arisen only by rearrangement of the amino acids in peptide bond. The peptide may have reacted with the lysine liberated by hydrolysis ... 

If the foregoing peptide" syntheses are envisaged as analogs of peptide synthesis in vivo it would still be necessary to find the physiological analogues of the carbobenzoxy (they might be acetyl) derivatives of the amino acids and of aniline and phenylhydrazine. This leaves the problem pretty much where it was before we need to find the reactive intermediates and to learn the mechanisms by which they are formed. 

Formation of a thiol ester is consistent with the spatial and chemical specificity of papain which is toward the amino acid residue bearing the carbonyl group of the sensitive bond. The moiety which is displaced from, or transferred to, the carbon of this carbonyl group may be any of the compounds mentioned above, e.g., a peptide, an amino acid, ammonia, aniline, hydrazine, hydroxylamine, an alcohol,... 

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