Amino Acids and Amines

Secondary amines are of the type, (CH3)2NH, dimethylamine, where two Hs are replaced by a carbon group such as CH3. Similarly (CH3)(C2H5)NH is called methylethylamine and (C2H5)2NH called diethylamine. 

Like ammonia, amines are alkaline in solution with high pH values. The tertiary amines are the most basic or alkaline and primary amines the least basic. They all 

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The modified procedure involves refluxing the N-substituted phthaUmide in alcohol with an equivalent quantity of hydrazine hydrate, followed by removal of the alcohol and heating the residue with hydrochloric acid on a steam bath the phthalyl hydtazide produced is filtered off, leaving the amine hydrochloride in solution. The Gabriel synthesis has been employed in the preparation of a wide variety of amino compounds, including aliphatic amines and amino acids it provides an unequivocal synthesis of a pure primary amine. 

Resolution of Racemic Amines and Amino Acids. Acylases (EC3.5.1.14) are the most commonly used enzymes for the resolution of amino acids. Porcine kidney acylase (PKA) and the fungaly3.spet i//us acylase (AA) are commercially available, inexpensive, and stable. They have broad substrate specificity and hydrolyze a wide spectmm of natural and unnatural A/-acyl amino acids, with exceptionally high enantioselectivity in almost all cases. Moreover, theU enantioselectivity is exceptionally good with most substrates. A general paper on this subject has been pubUshed (106) in which the resolution of over 50 A/-acyl amino acids and analogues is described. Also reported are the stabiUties of the enzymes and the effect of different acyl groups on the rate and selectivity of enzymatic hydrolysis. Some of the substrates that are easily resolved on 10—100 g scale are presented in Figure 4 (106). Lipases are also used for the resolution of A/-acylated amino acids but the rates and optical purities are usually low (107). 

Amino group An -NH2 group attached to a carbon skeleton as in the amines and amino acids. 

Organic nitrogen The nitrogen combined in organic molecules such as proteins, amines, and amino acids. 

Pharmacological Action. Certain of the simple amines and amino-acids found in ergot are pharmacologically active and have some influence on... 

The hydrazinolysis is usually conducted in refluxing ethanol, and is a fast process in many cases. Functional groups, that would be affected under hydrolytic conditions, may be stable under hydrazinolysis conditions. The primary amine is often obtained in high yield. The Gabriel synthesis is for example recommended for the synthesis of isotopically labeled amines and amino acids. a-Amino acids 9 can be prepared by the Gabriel route, if a halomalonic ester—e.g. diethyl bromomalonate 7—is employed as the starting material instead of the alkyl halide ... 

In the next section, a few illustrative examples of the use of ChiraLig for the analytical and three-stage preparative chiral separations involving amines and amino acids are presented and discussed. 

TRIFLUOROACETYLATION OF AMINES AND AMINO ACIDS UNDER NEUTRAL, MILD CONDITIONS N-TRIFLUOROACET ANILIDE AND N-TRIFLUOROACETYL-l-TYROSINE... 

The initial discoveries of the extension of the aromatic ring of the ortho-phthalaldehyde (OPA) to a naphthalene-2,3-dicarboxaldehyde (NBA) and the substitution of cyanide (CN ) for 2-ME as the nucleophile have provided the Center with a much more versatile reagent system (5,11), which maintains the sensitivity for primary aliphatic amines and amino acids, and now is known to form fluorescent products with oligopeptides, proteins, and other related analytes that possess a primary amine function (Equation 1). 

In the presence of mercaptoethanol [3, 12] o-phthalaldehyde reacts with primary amines and amino acids to yield fluorescent isoindole derivatives. 

Fluorescauiine Flur2Ui Primary amines and amino acids 550... 

The reaction of 5a-bromo-a-tocopherol (46) with amines was further elaborated into a procedure to use this compound as a protecting group Toe for amines and amino acids (Fig. 6.35).62 The protection effect was due to a steric blocking of the amino function by the bulky tocopheryl moiety rather than due to conversion into a non-nucleophilic amide derivative, and the Toc-protected amino acids were employed in the synthesis of dipeptides according to the dicyclohexylcarbodiimide (DCC) coupling method.64 The overall yield of the reaction sequence was reported to be largely dependent on the coupling reaction, since both installation and removal of the... 

A similar principle of increasing the reactivity of imidazolides was used for the acylation of cyclohexyl amine and amino acids in an aqueous system 11051... 

Figure 14.6 Enzymatic deracemization concepts for production of chiral alcohols, amines and amino acids...

R Schwyzer, M. Feuer, B Iselin. Activated esters. IB. Reactions of activated esters of amino acid and peptide derivatives with amines and amino acid esters. Helv Chim Acta 38, 83, 1955. 

One application in liquid chromatography which does alter the separation process is the use of a specific series of derivatives to enable the separation of chiral (optical isomers) forms of alcohols, amines and amino acids using reverse-phase separation. FLEC is available in the two chiral forms (+)-l-(9-fluorenyl) ethyl chloroformate and (—)-l-(9-fluorenyl) ethyl chlorofor-mate (Figure 3.12). Reaction of two stereoisomers of a test compound (e.g. T+ and T—) with a single isomer of the derivatizing reagent (e.g. R+) will result in the formation of two types of product, T+R+ and T—R+. It is possible to separate these two compounds by reverse-phase chromatography. 

A.B. Bourlinos, D. Gournis, D. Petridis, T. Szabo, A. Szeri, I. Dekany, Graphite oxide chemical reduction to graphite and surface modification with primary aliphatic amines and amino acids, Langmuir, 19 (2003) 6050-6055. 

Chen Z, Wu J, Baker GB, Parent M, Dovichi NJ. 2001. Application of capillary electrophoresis with laser-induced fluorescence detection to the determination of biogenic amines and amino acids in brain microdialysate and homogenate samples. J Chromatogr A 914(1—2) 293-298. 

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