Diamino acids separation

By this method of extracting the esters from their hydrochlorides, neither that of tyrosine, which remains behind combined with alkali, nor those of the diamino acids, which are soluble with difficulty in ether, are obtained. This is advantageous for the subsequent process of separation, but the method has the disadvantage that the whole quantity of esters is not taken up by the ether on account of their destruction by the alkali. In order to avoid their loss, the mass of carbonate is treated with excess of hydrochloric acid and evaporated down, the potassium... 

Only in a few cases has this compound been isolated from the products of hydrolysis of proteins, since its separation is extremely laborious. It can only be effected after all the other amino acids have been removed by crystallisation and by the ester method, and after the diamino acids have been precipitated by phosphotungstic acid. From the last mother-liquors it is obtained by crystallisation, and is best identified in the form of its /8-naphthalene sulpho-derivative. 

The separation and estimation of the two main groups of amino acids can be carried out in one experiment, instead of separately as described. The protein is hydrolysed by sulphuric acid, the tyrosine, cystine and diaminotrioxydodecanic acid are removed by crystallisation, and the diamino acids are precipitated by phosphotungstic acid. From this precipitate they are obtained by decomposition with baryta, and they are then separated by means of their silver compounds by Kossel, Kustcher and Patten s method. The filtrate from the phosphotungstic acid precipitate is freed from the excess of phosphotungstic acid by means of baryta, and the solution is treated by Fischer s ester method for the monoamino acids. 

When the mononitro-acid is nitrated, using mixed acid, a 78 per cent, yield of this acid results. It crystallises from boiling water in very small needles, and from glacial acetic acid in bunches of small, prismatic needles. Reduction in the usual way yields the diamino-acid, which separates in small, rhomb-shaped plates. The diamino-acid may be reduced to the oxide. 

Yamabe, Seno, and Takai [39] investigated the permeability of a monocarboxylic amino acid glutamic) and a diamino acid (lysine), solutions of which mixed with sodium chloride (0.1 N) were placed in the central cell of a five-compartment electrodialyzer. In the adjacent cells, which were separated from the central compartment by a cation-exchange membrane (on the cathodic side) and an anion-exchange membrane (on the anodic side), was placed 0.1 N sodium chloride solution. The changes in concentration of chloride and amino acid were determined as a function of the pH value in the central cell, which was varied by addition of alkali or hydrochloric acid. 

Quantitative separation of amino acids contained in protein hydrolyzates is a fairly complex problem, a substantial part of which can be solved by electrodialysis processes. The isoelectric points show that it is possible to separate a mixture of amino acids into at least three groups by making use of their ability to form ions of different charge depending on the pH of the solution. These three groups include monoaminocarboxylic acids, the isoelectric points of which are close to the pH of neutral solutions dicarboxylic acids, the isoelectric points of which lie in the acidic region and finally diamino acids, which are basic in nature. 

The substrate, catalyst and solvent were placed into a glass liner equipped with a magnetic stir bar. The liner was placed in a 250 mL steel autoclave that was then charged at r.t. first with N2, then with H2. The reaction mixture was stirred at r.t. until the hydrogen consumption ceased, after which the H2 was vented, the autoclave flushed with N2 and the reaction mixture filtered off on glass filter. The solution was evaporated and the products crystallized and filtered. The crystalline mixture contained the hydrochloride salt of diamino resorcinol and aniline In order to separate completely diamino resorcinol and aniline, the product mixture has to be recrystallized from hydrochloric acid solution. 

Simultaneously with Hansa Yellow G, compound 84 was first described as early as 1909 by Farbenfabriken Bayer. Its preparation starts from l-amino-4-bro-moanthraquinone-2-sulfonic acid (bromamine acid) 85. Dimerization is achieved through the Ullmann reaction, i.e., treatment with fine-grain copper powder in dilute sulfuric acid at 75°C. The separated intermediate, the disodium salt of 4,4 -diamino-l,l -dianthraquinonyl-3,3 -disulfonic acid 86, is heated to 135 to 140°C in the presence of 80% sulfuric acid in order to cleave the sulfonic acid groups [7] ... 

The protected (5)-4,8-diamino-3-oxooctanoic acid 99 was reduced with NaBH4, the resulting mixture of diastereomers was separated and the (3R,45)-product was derivatized with benzylated DHB (100). Then derivatized o-Ser-Gly was added and the serine OH-group was esterified with the protected OHAsp (101). The Gly carboxyl group was finally set free. 

G Galavema, MC Paganuzzi, R Corradini, A Dossena, R Marcelli. Enantiomeric separation of hydroxy acids and carboxylic acids by diamino-/3-cyclo-dextrin (AB, AC, AD) in capillary electrophoresis. Electrophoresis 22 3171— 3177, 2001. 

Direct amination of benzo[l,2-aqueous base with hydroxylamine-0-sulfonic acid gives a mixture of three diamino derivatives and two monoamino derivatives (Equation (15)). The combined yields of diamino and monoamino products are 45% and 48%, respectively. The three diamino derivatives can be separated by fractional crystallization from ethanol <86JOC979>. A-Amination of triazoles can also be achieved by treatment with NaH in DMF followed by O-amino-2,4-dinitrophenol <85TL335> or 0-(mesitylsulfonyl)hydroxyamine (9lJCS(Pl)2045>. 

Trans-diethylenediamino-diammino-cobaltic Nitrate, [Co en2 (XH3)2](N03)3, is formed when 1-, 2-dinitrito-diethylenediamino-cobaltic nitrate, [Co en2(N02)2]X03, is heated with nitric acid. It is first converted into the dinitrato-sait, which separates in dark red triclinie crystals. This then reacts with liquid ammonia, forming diethylene-diamino-diammino-eobaltic nitrate together with a small quantity of the ci.s-salt. The nitrate forms a red viscid syrup which is soluble in water and on the addition of potassium iodide yields the iodide, which separates from hot -water in small orange-yellow crystals or refractive rhombic plates. 

Benzoylation.—1 gm. of the diamino compound is treated with 4 gms. benzoyl chloride and 10 gms. dimethylaniline and boiled for 1 hour, when the benzoyl derivative separates out as a yellow-brown powder. The unchanged base and the dimethylaniline are extracted with dilute hydrochloric acid. The product is then filtered. 

Ferrarini et al. studied the reaction of 2,6-diamino- and 2-amino-6-acetamidopyridine with different jS-oxo esters in polyphosphoric acid at 80°C (90JHC881). Generally, complex reaction mixtures that contained different bi- and tricyclic products were obtained (see Scheme 7 and Table IX). The products were separated by flash chromatography. In the case of 2-amino-6-acetamidopyridine, the 2,6-diacetamidopyridine 97 was the main product. This compound 97 was also obtained by transamidation in good yield when 2-amino-6-acetamidopyridine was heated in polyphosphoric acid at 80°C. 2-Hydroxy-1,8-naphthyridines 98 were formed in a Conrad-Limpach-type cyclocondensation of 2-aminopyridines and /3-keto ester, while 4-hydroxy-1,8-naphthyridines 99 were probably formed by a ring transformation of 4//-pyrido[l,2-a]pyrimidin-4-ones 100 obtained by the cyclocondensation of 2-aminopyridines and a /3-keto ester. The cyclocondensation of 7-amino-4-hydroxy-l,8-naphthyridine 99 (R = H) and a... 

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