Aliphatic-derivatized

Amines, aliphatic Derivatization with 2,4-dinitrofluorobenzene or benzenesulfonyl chloride, solvent extraction with CH2CI2 GC-MS... 

Different aliphatic groups, i.e., methyl, ethyl, isopropyl, and tert-butyl groups, have been used to derivatize CF6. Slightly different separations are observed for these four aliphatic-derivatized CF6 CSPs due to the different bulkiness and geometry of the selected aliphatic groups. Overall, the isopropyl-derivatized CF6 produced the best enantiomeric separations for primary amines. 

Ten different aromatic derivatizations of CF6 were made. Examples of the enantiomeric separation of different classes of racemates are shown in Fig. 11. Most of the observed enantiomeric separations could be obtained on several different aromatic-derivatized CSPs [39]. In addition, the same elution order is generally obtained for chiral compounds on R- and S-naphthylethyl carbamate derivatized CSPs. These observations suggest that the enantiomeric selectivities of the aromatic-functionalized CF6 CSPs are more dependent on the chirality of the base CF6 than on the chirality of substituent groups. However, aromatic moieties play an indispensable role in chiral recognitions because the separations of non-primary amine compounds on aromatic-derivatized CF6 CSPs are generally better than those on aliphatic-derivatized ones. 

While native CF6 showed only limited enantioselectivity to a few compounds, derivatized CF6s appeared to be versatile chiral selectors and can be tuned for the best HPLC separation of different types of compounds. Aliphatic-derivatized cyclofructans operating in the polar organic mode provide best enantiomeric separations for primary amines. On the other hand, extensively aromatic-derivatized CF6 were able to separate a variety of different classes of enantiomers. Cyclofructans are the newest types of chiral selectors, and their further development and their applications in both analytical and preparative enantiomeric separations are not yet fully explored and are expected to grow significantly in the future. 

Nitro-bakterien, n.pl. nitrobacteria, -benzol, -benzin, n. nitrobenzene, -chinon, n. nitro-quinone. -cocussaure, /. nitrocoeeic acid, -derivat, n. nitro derivative, -farbstoff, m. nitro dye. -fettkorper, m. aliphatic nitro compound, -fettsaure, /. nitro fatty acid, -gruppe, /. nitro group, -halogenbenzole,... 

In analytical LC there are two primary reasons why chemical derivatization of the sample constituents would be necessary, and they are 1) to enhance the separation and 2) to increase the sensitivity of detection. Under certain circumstances, derivatization can also be used to reduce peak asymmetry, i.e. to reduce tailing, or to improve the stability of labile components so that they do not re-arrange or decompose during the chromatographic process. However, sensitivity enhancement is the most common goal of derivatization. For example, aliphatic alcohols that contain no UV chromaphore can be reacted with benzoyl chloride to form a benzoic ester. 

Reports on the use of fluorescent derivatives abound (5). Some reagents have become widely used. The dansyl group is probably the most thoroughly studied. Dansyl chloride has been widely used as a fluorescent derivatizing reagent for HPLC (6,7). It reacts readily with primary and secondary amino groups (7) and with phenols (8), but forms derivatives of alcohols very slowly (9). The lower detection limit for dansyl derivatives of aliphatic amines is in the range of 300 femtomoles per injection. 

This combination of the modified Bratton-Marshall reaction with prechromato-graphic derivatization with N-methyl-N-(4-aminophenyl)-amine allows specific detection of isocyanates, that is especially applicable to aliphatic isocyanates. 

Note This reagent sequence can be employed to great advantage after the prechromato-graphic derivatization of primary and secondary amines with 2,4-dinitrofluoro-benzene this makes for virtually specific detection of aliphatic amines. 

Possanzini, M. and Di Palo, V., Improved HPLC determination of aliphatic amines in air by diffusion and derivatization techniques, Chromatographia, 29,151, 1990. 

Phenylalanine and tryptophan contain aromatic side chains that, like the aliphatic amino acids, are also relatively non-polar and hydrophobic (Figure 1.4). Phenylalanine is unreactive toward common derivatizing reagents, whereas the indolyl ring of tryptophan is quite reactive, if accessible. The presence of tryptophan in a protein contributes more to its total absorption at 275-280nm on a mole-per-mole basis than any other amino acid. The phenylalanine content, however, adds very little to the overall absorbance in this range. 

Derivatized compounds with fluorophores (amino acids, steroids, aliphatic amines, carboxylic acids, catecholamines, etc.)... 

Kwakman et al. [65] described the synthesis of a new dansyl derivative for carboxylic acids. The label, N- (bromoacetyl)-A -[5-(dimethylamino)naphthalene-l-sulfonyl]-piperazine, reacted with both aliphatic and aromatic carboxylic acids in less than 30 min. Excess reagent was converted to a relatively polar compound and subsequently separated from the derivatives on a silica cartridge. A separation of carboxylic acid enantiomers was performed after labeling with either of three chiral labels and the applicability of the method was demonstrated by determinations of racemic ibuprofen in rat plasma and human urine [66], Other examples of labels used to derivatize carboxylic acids are 3-aminoperylene [67], various coumarin compounds [68], 9-anthracenemethanol [69], 6,7-dimethoxy-l-methyl-2(lH)-quinoxalinone-3-propionylcarboxylic acid hydrazide (quinoxalinone) [70], and a quinolizinocoumarin derivative termed Lumarin 4 [71],... 

Advantages include in this CL system the reagent is regenerated and it can be recycled, and derivatization is not required for many classes of compounds. Many aliphatic amines such as alkylamines, amino acids, proteins, antibiotics such as erythromycin and clindamycin, and NADH, among others can par-... 

A sensitive method for primary amines is shown in reaction 2, leading to the corresponding 7V-benzenesulfonyl-/V-trifluoroacetyl derivatives. These can be determined by GC-ECD using SE-30 columns LOD 1-5 pg, which is about 200 times more sensitive than GC-FID. The method was applied for determination of phenethylamine (33) in urine110. This analysis was performed also by LLE into n-pentane, derivatization to the benzenesulfonamide and GC-FPD using a capillary column recoveries of aliphatic primary amines in urine were 91-107%, RSD 0.2-4.5%111,112. Amines in environmental waters and sediments were determined after LLE with dichloromethane, derivatization with benzenesulfonyl chloride and GC-SIM-MS LOD 0.02-2 pg/L of water and 0.5-50 ng/g of sediment113. 

A study of fifty-five aliphatic, aromatic and heteroclyclic amines showed that twenty-eight of them could be detected in a FIA system at concentrations in the range of 1.0 x 10-10 to 4.0 x ] 0 6 M (SNR 3, 20 XL injection), without derivatization, by HPLC-CLD, taking profit of the chemiluminescence produced in the presence of aryl oxalate and sulforhodamine 101 (41). The method was applied to the determination of histamine (6) in fish146. See reaction 24 in Section IV.G. 

A determination of traces of low (Ci to C4) aliphatic amines in the atmosphere consists of passing air through an absorber containing phosphorous acid, derivatizing with m-toluyl chloride and end analysis by HPLC-UVD LOD 1-5 pmol of amine, corresponding to concentrations lower than 0.1 pg/m3 of air, in a 300 L sample232. 

Fig. 9.8 presents another, more complex type of phosphate prodrugs, namely (phosphoryloxy)methyl carbonates and carbamates (9-26, X = O or NH, resp.) [84], Here, the [(phosphoryloxy)methyl]carbonyl carrier appears quite versatile and of potential interest to prepare prodrugs of alcohols, phenols, and amines. The cascade of reactions leading from prodrug to drug as shown in Fig. 9.8 involves three steps, namely ester hydrolysis, release of formaldehyde, and a final step of carbonate hydrolysis (X = O) or A-decar-boxylation (X = NH). Three model compounds, a secondary alcohol, a primary aliphatic amine, and a primary aromatic amine, were derivatized with the carrier moiety and examined for their rates of breakdown [84], The alcohol, indan-2-ol, yielded a carrier-linked derivative that proved relatively... 

The production of optically active cyanohydrins, with nitrile and alcohol functional groups that can each be readily derivatized, is an increasingly significant organic synthesis method. Hydroxynitrile lyase (HNL) enzymes have been shown to be very effective biocatalysts for the formation of these compounds from a variety of aldehyde and aliphatic ketone starting materials.Recent work has also expanded the application of HNLs to the asymmetric production of cyanohydrins from aromatic ketones. In particular, commercially available preparations of these enzymes have been utilized for high ee (5)-cyanohydrin synthesis from phenylacetones with a variety of different aromatic substitutions (Figure 8.1). 

Direct and indirect chromatographic methods were developed and compared in systematic examinations for the enantioseparation of 10 aliphatic secondary a-amino acids direct separation of underivatized analytes involved the use of commercially available teicoplanin and ristocetin A CSPs [153], while indirect separation was based on precolumn derivatization with (5)-A-(4-nitrophenoxycarbonyl)phenylalanine methoxyethyl ester, with subsequent separation on a nonenantioselective column. 

Carbenes and transition metal carbene complexes are among the few reagents available for the direct derivatization of simple, unactivated alkanes. Free carbenes, generated, e.g., by photolysis of diazoalkanes, are poorly selective in inter- or intramolecular C-H insertion reactions. Unlike free carbenes, acceptor-substituted carbene complexes often undergo highly regio- and stereoselective intramolecular C-H insertions into aliphatic and aromatic C-H bonds [995,1072-1074,1076,1085,1086],... 

Analyses of the acetylated chloroform-insoluble residues (the acetylation reaction converts aliphatic and aromatic -OH groups to esters, allowing them to be clearly distinguished from water in the FTIR spectra) showed a similar rapid disappearance of the derivatized -OH groups above about 20% chloroform-solubles yield (16). ... 

Recently, a cell-permeable inhibitor of the human Gcn5 named MB-3 8 was discovered (Figure 11.3). This compound is structurally related to the a-methylene-y-butyrolactone class of compounds, a common structural element in a plethora of natural products. MB-3 was developed by appropriate derivatization of the basic y-butyrolactone motif without the arbitrary screening of large compound libraries. Interestingly, the length of the aliphatic side-chain is crucial for biological activity [17, 18]. 

Using derivatized glycine usually lowers the yields compared with sarcosin -nevertheless various functionalized glycine derivatives have been used. Amine 245, obtained by reaction of a trimethoxy-indole functionalized amino acid with an aliphatic co-amino-aldehyde, has been coupled with an oligonucleotide to increase the affinity of Cjq conjugates to certain nucleic acids (Figure 4.13) [288]. 

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