Analysis of Amines

Sulfanilatnides can be synthesized firani aniline through the following sequence of reactions  

Acetylation of aniline produces acetanilide (2) and protects the amino group from the reagent to be used next. Treatment of 2 with chlorosulfonic acid brings about an electrophilic aromatic substitution reaction and yields p-acetamidobenzenesulfonyl chloride (3). Addition of ammonia or a primary amine gives the diamide, 4 (an amide of both a carboxylic acid and a sulfonic acid). Finally, refluxing 4 with dilute hydrochloric acid selectively hydrolyzes the carboxamide linkage and produces a sulfanilamide. (Hydrolysis of carboxamides is much more rapid than that of sulfonamides.) 

Amines are characterized by their basicity and, thus, by their ability to dissolve in dilute aqueous acid (Sections 20.3A, 20.3E). Moist pH paper can be used to test for the presence of an amine functional group in an unknown compound. If the compound is an amine, the pH paper shows the presence of a base. The unknown amine can then readily be classified as 1°, 2°, or 3° by IR spectroscopy (see below). Primary, secondary, and tertiary amines can also be distinguished from each other on the basis of the Hinsberg test (Section 20.9A). Primary aromatic amines are often detected through diazonium salt formation and subsequent coupling with 2-naphthol to form a brightly colored azo dye (Section 20.8). 

Protons on the a carbon of an aliphatic amine are deshielded by the electron-withdrawing effect of the nitrogen and absorb typically in the 5 2.2-2.9 region protons on the /3 carbon are not deshielded as much and absorb in the range 8 1.0-1.7. 

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In the previous analysis for the second quadrant amines, there was evidence that the presence of an aromatic ring (BzAM) increased competition with the deactivating intermediate(s) and significantly the amount of DHQ obtained. The study was thus extended to other aromatic amines aniline (AN), 2-ethylaniline (2-ETAN), 3-ethylaniline (3-ETAN) and N-ethylaniline (N-ETAN). These amines are not classified in the literature analysis of amine properties (16), although aniline and pyridine were studied by statistical analysis of their solvent properties and classified in the same sector (16). By analogy, we hypothesize that these model aromatic amines should be classified in the second sector. Thus, they may aid in an understanding of the specific role of the aromatic ring and the effect of an alkyl substituent. 

Innumerable applications of chromatographic methods to the analysis of amines appeared in the recent literature concerning biogenic amines, drugs and their metabolites, pesticides and industrial intermediates however, due to the nonvolatile nature of many amines, application of the LC methods in Section IV.D became preponderant. 

Baker GB, Coutts RT, Martin IL. 1981. Analysis of amines in the central nervous system by gas chromatography with electron-capture detection. Prog Neurobiol 17 1. 

Another ion chromatography pharmaceutical application is the analysis of amines and amphoteric compounds such as choline (see Figure 19). Such compounds may be present either as counterions, as mentioned above, or as synthesis by-products. In either case, ion chromatography can be advantageously utilized for this class of compounds due to the limited utility of gas chromatography and the lack of a UV chromophore for such compounds. Again, screening for such compounds in pharmaceutical preparations can be best accomplished... 

Where the target analyte contains heteroatoms such as nitrogen, phosphorus and sulfur, atom-selective detectors can provide an ideal detection method. A number of examples appear in the literature of the use of a detector called a thermal energy analyser (TEA) for the measurement of A-nitroso compounds [14-17] and aromatic nitro compounds [18]. This has also been used as an HPLC detector [19, 20], and a modified TEA has been reported to be useful for analysis of amines and other nitrogen-containing compounds [17]. Unfortunately, this technique appears not to have gained in popularity, since no reports have appeared in the literature for over two decades. 

Analysis of Amines, Hydroxylamines, Amino Acids and Peptides via 0,0-Dibenzoyltartaric Acid Imides... 

Table 11. 1 H-NMR Analysis of Amines. Amino Acids, Esters, Peptides and Hydroxylamines via (/ ./ )-0,0 -Dibenzoyltartaric Acid Imides (5, CDC13)50...

Xiaohua, X., Liang, Z., Xia, L., and Shengxiang, J., Ionic liquids as additives in high performance liquid chromatography. Analysis of amines and the interaction mechanism of ionic liquids, Anal. Chim. Acta, 519,207-211,2004. 

Whereas, most of the varius porous polymers differ from each other only in selectivity, there are two major exceptions. Chromosorb 103 was developed specifically for analysis of amines and therefore is not suitable for acidic compounds. Tenax, because of its excellent thermal stability, can be used at much higher temperatures than the other porous polymers. Because of the minimal bleed from this material it has found use as a trapping medium for concentration of trace components (13) in air. These compounds are then desorbed from the Tenax and subsequently analyzed, permitting detection at much lower levels than by direct analysis of the air. 

Of halogenated acetyl derivatives, trifluoroacetyl derivatives are mainly used for the sensitive analysis of amines, particularly owing to their better chromatographic properties despite their ECD response being lower than that of chloroacetyl derivatives (cf., Table 4.7, p. 69). Trifluoroacetyl derivatives were exploited for the GC separation of a mixture of saturated and unsaturated homologues of amines up to C22 on conventional packed columns [71]. Mori et al. [72] developed a method for the quantitative and qualitative GC analysis of m- and p-xylenediamines in polyamides in the form of their t N -trifluoro-acetyl derivatives. An analogous method was elaborated for the analysis of ethanolamine for the presence of mono-, di- and triethanolamine [73]. A 1-ml volume of TFA anhydride is stoppered in a 2-ml vial, which is evacuated with the aid of a 10-ml injection syringe. 

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