Phenylethylamine derivatization

Fig. 7-6). Two unichiral amides which have been known capable of this reaction are 1-phenylethylamine [15] and l-(l-naphthyl)ethylamine [16]. Marfey s reagent [N-a-(2,4-dinitro-5-fluorophenyl)-L-alaninamide] was introduced as a reagent to deriva-tize amino acids with cyclopentane, tetrahydroisoquinoline or tetraline structures [17]. Simple chiral alcohols such as 2-octanol can also be used to derivatize acids such as 2-chloro-3-phenylmethoxypropionic acid [18]. 

Baker GB, Rao TS, Coutts RT. 1986a. Electron-capture gas chromatographic analysis of p-phenylethylamine in tissues and body fluids using pentafluorobenzenesulfonyl chloride for derivatization. J Chromatogr Biomed Appl 381 211. 

A problem in trying to use these results in developing potential pest control agents is that none of these compounds is likely to penetrate either the cuticle or the CNS of insects effectively, since all are fully ionized at physiological pH. Derivatization of the polar groups would be one possible solution to this problem. The formamidines and imidazolines generally do not suffer from this problem since they have pKas which are lower than those of the related phenylethylamines and thus are at least partly in the free base form at pH 7. 

Table 5.1 Derivatization of 1-phenylethylamine into a conglomerate upon salt formation with an achiral acid.

Edwards and colleagues have reported derivatization with 2,4-dinitrobenzene sulfonic acid, a procedure useful for quantification of a number of phenylethylamines, to be unsuitable for analysis of HA. However, Doshi and Edwards discovered that 2,6-dinitro-4-trifluoromethyl benzenesulfonic acid (DNTS) reacts readily with catecholamines, histamines, and related biogenic amines with very suitable properties for GC-ED. Formation of the trifluoroacetyl, trimethylsilyl, and heptafluoro butyryl derivatives of HA for GC have been reported, but these compounds have been found to be unsuitable for quantification of HA because of excess tailoring. 

Figure 1. The effect of polytetrafluoroethylene on perfluoroacyl derivatization. The profile in curve A was obtained from derivatization of / -phenylethylamine (PE) with pentafluorobenzoyl chloride (PFBzO-Q) in an zill-glass system, that in curve B from the same reaction in a reaction vial sealed with a polytetrafluoroethylene-lined cap. Peak 1 PE derivative peak 2 derivative of the internal standard, tolylethylaminc (Ref. 13). Note the major peak of pentafluorobenzoic acid, the other by-products, and the reduced yield of derivatives in profile B.

Comments Although the reaction with butylamine was quantitative without the use of a catalyst, Helmchen et al. [63] included a 1-molar equivalent of 2-hydroxypyridine in the derivatization of racemic 2-butyrolactones with S( —)-l-phenylethylamine. Engel et al. [129] carried out carbamoylation of the hydroxy group with R( + )-phenyl-ethylisocyanate in the presence of 4-aminopyridine, which not only catalysed the reaction but also prevented recyclization of the lactone. 

Pirkle and Murray first reported the temperature-dependent elution order reversal in Pl-basic proline-derivatized CSPs in 1993. They used (/ 5)-A-(3,5-dinitrobenzoyl)-a-phenylethylamine as the solute to investigate the response of the chromatographic behavior by changing the temperature on the CSP. 

Chiral recognition for 1-phenylethylamine perchlorate(6). Extraction of aqueous 1-phenylethylamine perchlorate(6) with crown ethers(4) and the determination of the amount of extracted amine was carried out by the same procedure as described for a-phenylglycine methyl ester perchlorate. Another 10 ]ll portion of organic phase was derivatized with (-)-(L) N-trifluoroacetylalanine and used for the determination of CRF by GLC(OV-17 coated glass capillary column at 160 °C). 

Kaddoumi, A. Kubota, A. Nakashima, M.N. Takahashi, M. Nakashima, K. High performance liquid chromatography with UV detection for the simultaneous determination of sympathomimetic amines using 4-(4,5-diphenyl-lH-imidazole-2-yl)benzoyl chloride as a label, Biomed.Chromatogr., 2001, 15, 379-388. [human rat plasma derivatization LOD 50-100 nM ephedrine norephedrine 2-phenylethylamine fenfluramine phentermine cyclohexylamine fluoxetine is internal standard pharmacokinetics]... 

The experimental observation that the retention time of amino acids derivatized with FDAA were dependent on the hydrophobicity of amino acids further confirms the proposed mechanism, for example, the FDAA derivative of an amino acid, which has a larger difference in hydrophobicity between the a -carboxyl group and the side chain, has a longer retention time and a better resolution. Separation behavior of FDAA derivatives of amino acid methyl esters and amino compounds without the a-carboxyl group, such as 1-phenylethylamine, alanilol, and valinol. 

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